TGC INDUSTRIES INC
10KSB, 2000-04-04
PLASTICS, FOIL & COATED PAPER BAGS
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                    U.S. SECURITIES AND EXCHANGE COMMISSION
                           Washington, D.C. 20549

                                  FORM 10-KSB

       ANNUAL REPORT UNDER SECTION 13 OF 15(d) OF THE SECURITIES EXCHANGE
                  ACT OF 1934 For the Fiscal Year Ended December 31, 1999

                         Commission File Number 0-14908

                             TGC INDUSTRIES, INC.
               (Name of small business issuer of its charter)

                Texas                                 74-2095844

 (State or other jurisdiction of               (I.R.S. Employer Identification
 incorporation or organization)                     No.)


         1304 Summit, Suite 2, Plano, Texas             75074
       (Address of principal executive offices)      (Zip Code)

                  Issuer's telephone number:  (972) 881-1099

      Securities registered under Section 12(b) of the Exchange Act:  NONE

         Securities registered under Section 12(g) of the Exchange Act:
                          Common Stock ($.30 Par Value)
    Series C 8% Convertible Exchangeable Preferred Stock ($1.00 Par Value)

Check  whether the issuer (1) filed all reports  required to be filed by Section
13 or 15(d) of the  Exchange  Act during the past 12 months (or for such shorter
period that the registrant was required to file such reports),  and (2) has been
subject to such filing requirements for the past 90 days. Yes X No __

Check if there is no disclosure of delinquent filers in response to Item 405
of Regulation S-B contained in this form, and no disclosure will be contained,
to the best of registrant's knowledge, in definitive proxy or information
statements incorporated by reference in Part III of this Form 10-KSB or any
amendment to this Form 10-KSB. (X)

State issuer's revenues (from continuing operations) for its most recent
fiscal year:                                                       $4,600,708

State the aggregate market value of the voting stock (Common Stock and
Series C 8% Convertible Exchangeable Preferred Stock) held by non-affiliates
computed by reference to the price at which the stock was sold on March 10,
2000:                                                              $4,593,266

State the number of shares outstanding of each of the issuer's classes of common
equity, as of the latest practicable date.

             Class                           Outstanding as of March 10, 2000
Common Stock ($.30 Par Value)                            2,267,124



<PAGE>



                     Documents Incorporated by Reference

           Document  Part of the Form  10-KSB  Into Which  Portions of the Proxy
Statement the Document is Incorporated for Annual Meeting of shareholders  Items
9 through 12 of Part III to be held on May 11, 2000

                                    Part I

ITEM 1. DESCRIPTION OF BUSINESS.

     TGC Industries, Inc. ("TGC" or the "Company") is a Texas corporation
engaged in the geophysical service business, primarily conducting Three-D
("3-D") surveys for clients in the oil and gas business.  TGC's principal
business office is located at 1304 Summit Avenue, Suite 2, Plano, Texas 75074.
(Telephone: 972-881-1099).

                                    History

     In April 1980, Supreme  Industries,  Inc.,  formerly ESI Industries,  Inc.,
("Supreme")  formed a wholly owned subsidiary that acquired  certain  equipment,
instruments,   and  related   supplies  of  Tidelands   Geophysical   Co.,  Inc.
("Tidelands"),  a Houston-based  corporation that had been organized in 1967 and
was engaged in the business of conducting seismic, gravity, and magnetic surveys
under  contracts to companies in the  exploration for oil and gas. In July 1986,
Tidelands' name was changed to TGC Industries,  Inc. ("TGC").  On June 30, 1986,
the  Board  of  Directors  of  Supreme  and  TGC  approved  a  spin-off  whereby
substantially  all of the shares of TGC owned by Supreme were  distributed  as a
stock dividend to Supreme security holders.

     On July 30, 1993, TGC acquired,  through a wholly owned  subsidiary,  Chase
Packaging  Corporation  ("Chase"),  a specialty packaging business,  principally
supplying products to the agricultural industry, through the purchase of certain
assets of the Chase Packaging division of Union Camp Corporation.

     In June 1996, the Board of Directors of TGC approved the spin-off of Chase,
effective  July 31,  1996,  whereby all of the shares of Chase owned by TGC were
distributed  as a stock dividend to the  shareholders  of TGC under the terms of
the spin-off transaction.  Pursuant to the terms of the spin-off,  and following
clearance  by the  Securities  and  Exchange  Commission  on March 7, 1997,  the
holders of TGC's Common Stock and, on an  as-if-converted  basis, the holders of
TGC's Series C 8% Convertible Exchangeable Preferred Stock received the dividend
distribution of Chase Common Stock.

     During  July  1996,  the  Company  issued  1,150,350  shares of Series C 8%
Convertible  Exchangeable  Preferred Stock in a private placement  offering with
gross proceeds of approximately $5,800,000.

     The Preferred  Stock sold in the private  placement  entitles the holder to
receive  cumulative  cash  dividends  as,  when and if  declared by the Board of
Directors  at a rate of 8% per annum prior to any  dividend or  distribution  in
cash or other  property on any class or series of stock junior to the  preferred
stock. The dividends on the Preferred Stock are payable as, when and if declared
by the  Board of  Directors  on  January 1 and July 1 of each  year,  commencing
January 1, 1997. The dividend on the Preferred Stock is cumulative.

     From the proceeds of the private placement, TGC made a capital contribution
to Chase of $2,716,403 to facilitate the spin-off;  and TGC retained  $2,000,000
for the purchase of state-of-the-art  geophysical recording equipment. Under the
terms of the  spin-off,  the  effective  date of which was July,  31, 1996,  TGC
completed  the  spin-off  of the  business  and  assets  relating  to the  Chase
operations,  except TGC retained the Portland,  Oregon facility and canceled all
inter-company  debt owed by Chase to TGC.  The  distribution  of Chase Stock was
March 7, 1997.  On March 18, 1997,  TGC sold the Portland,  Oregon  facility for
$2,430,000   and  applied  such  proceeds  in   satisfaction   of  the  mortgage
indebtedness  with  respect  to  such  facility  and in  satisfaction  of a debt
obligation  owing by TGC to Chase to pay to Chase any such proceeds in excess of
the amount of the mortgage indebtedness.

     As of July 31, 1996,  the effective date of the spin-off,  TGC  Industries,
Inc.'s  only  business  has been the  geophysical  service  business,  primarily
conducting Three-D ("3-D") surveys for clients in the oil and gas business.

     On December 13, 1999, WEDGE Energy Services,  L.L.C., an affiliate of WEDGE
Group Incorporated,  a diversified Houston, Texas firm with interests in oil and
gas services,  purchased a $2,500,000 8 1/2% convertible  subordinated debenture
of the Company.  Proceeds of the financing  together with other  available funds
are being  utilized  for working  capital and an  expanded  capital  expenditure
program.  The  debenture,  at  WEDGE's  option,  may be  converted  into  either
preferred stock or common at a price of $1.15 per share.

                General Description of the Company's Business

                            Geophysical Business

     Since its formation,  TGC has engaged in the domestic  geophysical services
business  principally  through conducting seismic surveys and to a lesser extent
through sales of gravity  information  from the Company's Data Bank to companies
engaged in the exploration  for oil and gas in the United States.  Geophysics is
the study of the structure and composition of the earth's  interior and involves
the measuring and  interpretation  of the earth's  properties  with  appropriate
instruments.  Such studies are generally conducted by means of surveys performed
by field crews employing seismic,  gravity,  or magnetic  instruments to acquire
data that is then interpreted by various means to obtain useful  information for
oil and gas  companies.  The  two  survey  techniques  used  by the  Company  in
acquiring geophysical data are seismic and gravity. Land seismic surveys are the
Company's  principal  method of data  acquisition and are by far the most widely
used  geophysical  technique.  TGC's  seismic  crews use dynamite as the primary
energy source for such surveys.

     In July 1996,  the Company  purchased  an Opseis  Eagle 24-BIT 1500 channel
recording  system,  cables and geophones  for  approximately  $2,900,000,  using
$2,000,000 from proceeds from the Company's preferred stock private placement, a
$750,000  equipment  loan,  and funds from  internal cash flow. In late November
1996,  the Company  purchased  a second  1000  channel  Eagle  system  using the
proceeds  and  trade-in  from  TGC's  two older  systems  along  with  equipment
financing  of  $855,000  and  internal  cash flow.  In 1997,  TGC  purchased  an
additional  1500  channels  utilizing  equipment  financing of  $2,242,685.  The
greater precision and improved subsurface resolution obtainable from 3-D seismic
data have  enabled  energy  companies in the U.S. to better  evaluate  important
subsurface features.  The processing and interpretation of seismic data acquired
by TGC are transmitted by the Company to data  processing  centers (not owned or
operated by the Company) designated by the clients for processing.

     The  Company's  Data Bank  contains  gravity  data,  and to a lesser extent
magnetic data, from many of the major oil and gas producing areas located within
the United States.  TGC does not have a seismic data bank. Data Bank information
has been amassed through  participatory  surveys as well as speculative  surveys
funded by TGC alone. All data and  interpretations  may be licensed to customers
at a fraction of the cost of newly acquired data.

     As a service business, the Company's domestic geophysical services business
is not  dependent  upon the supply of raw  materials or any other  products and,
therefore,  the  Company  does  not  have  arrangements  with  any raw  material
suppliers.

     The Company has the  capability  of utilizing  two seismic crews to perform
its  geophysical  services and, in any given period,  these crews may generate a
significant  portion of their  revenues from one or more clients.  However,  the
Company operated only one crew during the year 1999. For the year ended December
31, 1999,  three  customers  accounted  for  thirty-eight  percent  (38%),twenty
percent (20%) and sixteen percent (16%) of the Company's revenue,  respectively.
The Company  enters into a general or master  agreement with each of its clients
for the provision of geophysical  services and a supplementary  agreement (which
becomes a part of the general  agreement)  with respect to each  particular  job
that the Company  performs for a client.  Under the terms of such agreements the
Company  generally  contracts  to  supply  all  personnel,   transportation  and
equipment to perform seismic surveys for a given prospect for a fixed price plus
reimbursement  for certain third party charges.  The Company generally bills its
clients on a  progressive  basis over the term of the  contract.  The Company is
generally obligated to maintain insurance against injury or damage to persons or
equipment  arising from the  performance  of its  services and to indemnify  its
customers  against  all  claims  and  liability  arising  therefrom.  Management
believes this insurance coverage is sufficient.

     Prior to the second half of 1998, activity in the U.S. Geophysical Industry
had increased with the success and acceptance of 3-D surveys.  The improved cost
effectiveness gained from the data acquisition and processing of 3-D surveys had
resulted  in  increased  profits  for  the  U.S.  operations  of the  major  and
independent  oil companies.  With these cost  advantages and the  uncertainty of
foreign operations, many of the major U.S. oil companies increased participation
in the domestic oil  industry.  However,  beginning  approximately  in mid 1998,
activity declined significantly due to a decline in the price of oil.

     Due to a significant  decline in spending for seismic  services by a number
of oil and gas clients as a result of  significantly  lower oil prices,  TGC has
reduced its operations to one seismic acquisition crew. At December 31, 1999 the
Company's crew was inactive. This decrease in spending was primarily a result of
the significant  decline in oil and gas prices  (principally  oil prices) during
1998.  Although oil and gas prices have  returned to early 1998 levels and above
in recent  months,  spending for seismic  services  remains slow. As a result of
this  reduced  activity  1999  did not  compare  favorably  with  1998.  Company
management  continues to monitor  expenses  and where  possible  implement  cost
containment  programs to remain highly competitive through this continued period
of reduced industry activity.  Management believes that the geophysical services
market  conditions  should  improve  beginning in the second quarter of 2000 and
seismic  services  should be in greater  demand due to the  recent  increase  in
levels of  seismic  bidding  activity  and the  prospect  of oil and gas  prices
remaining at or near their  current  levels.  Though there can be no  assurance,
such  conditions  should enable the Company to secure  contracts and improve its
performance.

     As of December 31, 1999, TGC employed 50 employees,  supporting one seismic
crew with a total of 43 crew  members and direct  support  members.  The Company
believes its relationship with its employees to be satisfactory.


ITEM 2. DESCRIPTION OF PROPERTY.

     The Company's headquarters are in leased facilities located in Plano, Texas
from which it conducts  all its current  operations.  These  facilities  include
8,000 square feet of office and warehouse  space and an outdoor  storage area of
approximately  10,000 square feet. The monthly rent is $4,810.  This facility is
used  to  house  corporate  offices  and  serves  as the  headquarters  for  the
geophysical   business.   The  Company  is  not  responsible  for  insuring  the
facilities. The condition of the Company's facilities is good and TGC management
believes  that these  properties  are suitable  and  adequate for the  Company's
foreseeable needs.


ITEM 3. LEGAL PROCEEDINGS.

     The Company is a defendant in various  legal  actions that arose out of the
normal  course of business.  In the opinion of  Management,  none of the actions
will result in any significant loss to the Company.


ITEM 4. SUBMISSION OF MATTERS TO A VOTE OF SECURITY HOLDERS.

     No matters were submitted by the Company,  during the fourth quarter of the
fiscal  year  ended  December  31,  1999,  to a vote of the  Company's  security
holders, through the solicitation of proxies or otherwise.

                                   Part II

ITEM 5. MARKET FOR COMMON EQUITY AND RELATED STOCKHOLDER MATTERS.

     The Company's  Common Stock has traded on the NASDAQ  SmallCap Market under
the symbol "TGCI" since September 25, 1994.

     The number of shareholders of record of TGCI's Common Stock as of March 10,
2000,  was 306. Due to the number of shares held in nominee or street name,  the
Company  believes that there are a  significantly  greater  number of beneficial
owners of its Common Stock. As of such date, CEDE & CO. held 1,161,451 shares in
street name. On March 10, 2000, TGC's Common Stock was quoted at a closing sales
price of $1.50.  High and low sales prices  (adjusted for the Reverse  Split) of
TGC's Common Stock for the period of January 1, 1998, to December 31, 1999, were
as follows:

<TABLE>

                        Sales Price of TGC Common Stock

Date                                    High                 Low

<S>     <C>           <C> <C>           <C>                 <C>
October 1 -- December 31, 1999          1                   7/16

July 1 -- September 30, 1999            1 15/16              1/4

April 1 -- June 30, 1999                3                    7/8

January 1 -- March 31, 1999             1 1/2                7/8

October 1 -- December 31, 1998          2 1/4                3/4

July 1 -- September 30, 1998            2 5/8              1 1/2

April 1 -- June 30, 1998                3 3/8            1 11/16

January 1 -- March 31, 1998             3 9/16             2 5/8
</TABLE>

     The above sale quotations were furnished to TGC by the NASD.

     On November 6, 1998,  the Company  effected a  one-for-three  reverse stock
split of its Common Stock,  whereby each three shares of issued and  outstanding
Common  Stock was  converted  and  combined  into one share of Common Stock (the
"Reverse  Split").  The Common Stock commenced  trading on a post-Reverse  Split
basis on November 9, 1998.

     As a consequence of the Reverse  Split:  (1) pursuant to the provisions for
adjustment  of the  conversion  ratio  of the  Company's  Preferred  Stock,  the
conversion  price  per  share of  Common  Stock on a  post-Reverse  Split  basis
increased  from  $0.75 to $2.25 per  share;  and (2)  pursuant  to the terms for
adjustment  to  the  exercise  price  of the  Company's  Common  Share  Purchase
Warrants,  each Warrant purchases on a post-Reverse  Split basis, 1/3 of a share
of Common Stock at a price of $1.125 per share of Common Stock.

     On  December  10,  1998,  the TGC Board of  Directors  voted to extend  the
expiration  date of its Common Stock Purchase  Warrants until December 31, 2000.
The Warrants were otherwise scheduled to expire on December 31, 1998. On June 3,
1999, the TGC Board of Directors, in lieu of declaring the July 1999 semi-annual
dividend on the Preferred Stock, voted to reduce, on a post-Reverse Split basis,
the  initial  conversion  price of the  Preferred  Stock from $2.25 per share of
Common Stock to $2.00 per share of Common Stock and to delay the increase in the
conversion  price of the Preferred Stock until the close of business on December
31, 2001. The increase in the conversion price of the Preferred Stock from $2.00
per share of Common  Stock to $3.75 per  share of Common  Stock,  following  the
reduction  described above, was otherwise  scheduled to increase at the close of
business on December 31, 2000. As a result of the adjustments  described  above,
the conversion  price of the Preferred  Stock is $2.00 per share of Common Stock
if exercised prior to the close of business on December 31, 2001. After December
31, 2001 and prior to the close of business on December 31, 2002, the conversion
price per share of Common Stock shall be $3.75. Thereafter, the conversion price
will be $6.00 per share of Common Stock.

     Dividends  are payable on the Company's  Common Stock at the  discretion of
the Board of Directors. In light of the working capital needs of the Company, it
is  unlikely  that cash  dividends  will be declared  and paid on the  Company's
Common Stock in the foreseeable future.


ITEM 6. MANAGEMENT'S DISCUSSION AND ANALYSIS OF FINANCIAL
        CONDITIONS AND RESULTS OF OPERATIONS.

                           Results of operations

                Geophysical Operation  (Continuing Operations)

     Revenues for the year ended December 31, 1999 were $4,600,708 compared with
revenues  of  $17,073,506  for the year ended  December  31,  1998.  The Company
incurred  a net loss,  before  dividend  requirements  on  preferred  stock,  of
$(2,073,071) for the year ended December 31, 1999. Net earnings, before dividend
requirements on preferred stock, were $1,831,602 for the year ended December 31,
1998.  EBITDA  was  $484,531  or $.09 per share on a diluted  basis for the year
ended December 31, 1999, compared with $3,872,760 or $.81 per share on a diluted
basis for the year ended December 31, 1998.

     The  Company's  shareholders,  at a  special  meeting  of  shareholders  on
November  5,  1998,   approved  an  Amendment  to  the  Company's   Articles  of
Incorporation to effect a one-for-three  reverse stock split of its Common Stock
(the "Reverse  Split").  The Reverse Split was effected on November 6, 1998, and
the Common Stock commenced trading on a post-Reverse  Split basis on November 9,
1998. All references to number of shares,  except shares authorized,  and to per
share information have been adjusted to reflect the reverse stock split.

     TGC's cost of services, as a percentage of revenue,  increased to 113.1% in
1999 from 80.9% in 1998.  This  percentage  increase was principally a result of
the lower revenue level in 1999.  Selling,  general and  administrative  expense
decreased  to  $878,940  in 1999  from  $1,160,228  in  1998.  Interest  expense
decreased  by $58,983 in 1999 when  compared  to 1998  primarily  as a result of
certain debt which matured  during 1999. In addition,  during the fourth quarter
of 1999, the Company recorded a charge to earnings of $391,000 for an adjustment
related to debt financing costs incurred in connection with the issuance of debt
securities with detachable  stock warrants.  The debt was re-paid by the Company
in  the  fourth  quarter  of  1999.   Non-cash   charges  for  depreciation  and
amortization  were $1,885,313 in 1999 compared with $1,778,454 in 1998. Due to a
significant  decline in spending for seismic services by a number of oil and gas
clients  as a  result  of  significantly  lower  oil  prices,  TGC  reduced  its
operations to one seismic  acquisition  crew in 1999.  This decrease in spending
was  primarily  a  result  of the  significant  decline  in oil and  gas  prices
(principally  oil prices) during 1998 and early 1999. For over thirty years, TGC
has  successfully  served the  geophysical  industry.  However,  the Company was
unable to obtain a sufficient  number of  contracts  during 1999 to operate at a
profitable level. The Company has substantially reduced its break-even levels to
increase  competitiveness.  There has been a recent  increase in seismic bidding
activity  and  management  is  aggressively  pursuing  contract   opportunities.
Management  believes that the  geophysical  services  market  conditions  should
improve in 2000 and  seismic  services  should be in  greater  demand due to the
recent  increase in levels of seismic  bidding  activity and the prospect of oil
and gas prices remaining at or near their current levels. Though there can be no
assurance,  such  conditions  should enable the Company to secure  contracts and
improve its performance.


     At December 31, 1999,  the Company had net operating loss carry forwards of
approximately $5,600,000 available to offset future taxable income, which expire
at various dates through 2019.

                             Financial Condition

     Cash of $404,418 was  provided by  operations  for the twelve  months ended
December 31, 1999,  compared  with cash  provided by  continuing  operations  of
$2,259,490  for the same period of the prior year.  The funds  generated in 1999
were primarily  attributable to the collection of trade receivables and non-cash
depreciation  and  amortization  charges.  Proceeds  from the sale of  equipment
provided cash from investing activities for 1999. Cash was provided by financing
activities  primarily  as a  result  of  the  purchase  of a  $2,500,000  8 1/2%
convertible  subordinated  debenture,  which matures  December 1, 2009, by WEDGE
Energy Services,  L.L.C. WEDGE Energy Services,  L.L.C. is an affiliate of WEDGE
Group  Incorporated  a  diversified  Houston firm with  interests in oil and gas
services.  Proceeds of the  financing  together with other  available  funds are
being utilized for working capital and an expanded capital expenditure  program.
The debenture,  at Wedge's option,  may be converted into either preferred stock
or common at a price of $1.15 per share.

     Working  capital  increased  $1,963,112 to $1,092,391 from the December 31,
1998,  working  capital  deficit  of  $(870,721),  primarily  as a result of the
purchase of the  $2,500,000  convertible  subordinated  debenture by WEDGE.  The
Company's current ratio increased to 2.3 to 1.0 at December 31, 1999 from .72 to
1.0 at December 31,  1998.  Stockholders'  equity  decreased  to  $3,493,612  at
December  31,  1999,  from the December  31,  1998,  balance of  $5,127,856  due
primarily to the net losses incurred by the Company during 1999.

     During the fourth quarter of 1998,  the Company  renewed its revolving bank
line of credit with a major bank in an amount of up to  $1,000,000.  The line of
credit bears  interest at prime plus 1.5%,  is  collateralized  by equipment and
accounts receivable and requires the maintenance of certain financial ratios. As
a result of the losses  reported in 1999, the Company had not been in compliance
with  certain  required  covenants  since the first  quarter  of 1999.  The bank
decided not to waive the covenant violation. As a result, the Company was unable
to use its  revolving  line of credit  for most of 1999.  The  revolving  credit
agreement matured in the fourth quarter of 1999 and was not renewed by the bank.
At the present  time the Company does not have the  availability  of a revolving
line of credit.

     The Company began preparation for the year 2000 issues during 1996. In late
1996,  TGC  upgraded  and replaced its  accounting  software.  In addition,  TGC
installed a small personal computer network. The cost of these additions,  which
are year 2000 compliant,  was approximately  $15,000. TGC uses an outside source
for its payroll  services  and has been assured by this vendor that its software
is year 2000  compliant.  TGC made a few  additional  hardware  upgrades  in the
fourth quarter of 1999 making the Company fully year 2000 compliant. To date all
systems  have  performed  correctly  and the  Company  has not  experienced  any
problems in year 2000.

     The Company  anticipates  that available  funds,  together with anticipated
cash flows  generated  from future  operations  will be  sufficient  to meet the
Company's cash needs during 2000, so long as the Company's one crew is employed,
of which there is no assurance.

                           Forward-Looking Statements

     This report contains  forward-looking  statements which reflect the view of
Company's management with respect to future events. Although management believes
that  the  expectations   reflected  in  such  forward-looking   statements  are
reasonable,  it can give no assurance that such  expectations will prove to have
been  correct.  Important  factors  that could  cause  actual  results to differ
materially from such expectations are disclosed in the Company's  Securities and
Exchange Commission filings, and include, without limitation,  the unpredictable
nature of forecasting weather, the potential for contract delay or cancellation,
and the potential for  fluctuations in oil and gas prices.  The  forward-looking
statements   contained  herein  reflect  the  current  views  of  the  Company's
management and the Company  assumes no obligation to update the  forward-looking
statements  or to update the  reasons  actual  results  could  differ from those
contemplated by such forward-looking statements.


                                                       2


<PAGE>



ITEM 7. FINANCIAL STATEMENTS.

                               Financial Statements
                            December 31, 1999 and 1998

                                      CONTENTS

Report of Independent Certified Public Accountants                  p. 11
       Financial Statements

Balance Sheets                                                      p. 12
Statements of Operations                                            p. 14
Statement of Stockholders' Equity                                   p. 15
Statements of Cash Flows                                            p. 16
Notes to Financial Statements                                       p. 18



                                                       3


<PAGE>



               Report of Independent Certified Public Accountants

Board of Directors and Stockholders
TGC Industries, Inc.

We have audited the  accompanying  balance sheets of TGC Industries,  Inc. as of
December  31,  1999  and  1998,  and  the  related   statements  of  operations,
stockholders'  equity and cash flows for the years then ended.  These  financial
statements   are  the   responsibility   of  the   Company's   management.   Our
responsibility  is to express an opinion on these financial  statements based on
our audits.

We conducted our audits in accordance with auditing standards generally accepted
in the United States. Those standards require that we plan and perform the audit
to obtain reasonable  assurance about whether the financial  statements are free
of material misstatement. An audit includes examining, on a test basis, evidence
supporting  the amounts and  disclosures in the financial  statements.  An audit
also includes assessing the accounting principles used and significant estimates
made by  management,  as well as  evaluating  the  overall  financial  statement
presentation.  We believe  that our audits  provide a  reasonable  basis for our
opinion.

In our opinion,  the financial  statements  referred to above present fairly, in
all material  respects,  the financial  position of TGC  Industries,  Inc. as of
December 31, 1999 and 1998, and the results of its operations and its cash flows
for the years then ended,  in conformity with  accounting  principles  generally
accepted in the United States.

/s/ Grant Thornton LLP

GRANT THORNTON LLP

Dallas, Texas
February 4, 2000

                                                       4


<PAGE>



                            TGC Industries, Inc.

                               BALANCE SHEETS

                                December 31,
<TABLE>


               ASSETS                                     1999         1998
                                                        ---------   ---------
CURRENT ASSETS


<CAPTION>
<S>                                                  <C>           <C>
  Cash and cash equivalents                          $  1,898,674  $  702,999
  Trade accounts receivable                                    -    1,113,185
  Costs and estimated earnings in excess of billings

    on uncompleted contracts                                   -      144,972
  Prepaid expenses and other                               44,479     126,419
  Deferred income taxes                                        -      202,000
                                                        ---------   ---------
        Total current assets                            1,943,153   2,289,575

PROPERTY AND EQUIPMENT - at cost

  Machinery and equipment                              10,839,242  10,836,839
  Automobiles and trucks                                  600,703     706,810
  Furniture and fixtures                                  317,167     317,167
  Other                                                    18,144      18,144
                                                        ---------   ---------
                                                       11,775,256  11,878,960

      Less accumulated depreciation and amortization  ( 6,712,004) (4,903,212)
                                                        ---------   ---------
                                                        5,063,252   6,975,748

DEFERRED INCOME TAXES                                     202,000          -

OTHER ASSETS                                                  495         963
                                                        ---------   ---------
                                                       $7,208,900  $9,266,286

                                                        =========   =========


                                                       5
</TABLE>


<PAGE>



                              TGC Industries, Inc.
<TABLE>

                            BALANCE SHEETS - CONTINUED

                                   December 31,

<CAPTION>
  LIABILITIES AND STOCKHOLDERS' EQUITY                     1999        1998
                                                        ---------   ---------
CURRENT LIABILITIES

<S>                                                <C>             <C>
  Line of credit                                   $         -     $  290,000
  Trade accounts payable                                 50,932       576,305
  Accrued liabilities                                    60,362       332,717
  Federal income taxes payable                               -         25,191
  Billings in excess of costs and estimated earnings

   on uncompleted contracts                                  -        532,446
  Current maturities of long-term obligations           739,468     1,403,637
                                                      ---------     ---------
        Total current liabilities                       850,762     3,160,296

LONG-TERM OBLIGATIONS, less current maturities        2,864,526       978,134

COMMITMENTS                                                  -             -

STOCKHOLDERS' EQUITY
  Preferred stock, $1.00 par value;

   4,000,000 shares authorized;
   1,115,750 and 1,129,350 shares

   issued in 1999 and 1998, respectively              1,115,750     1,129,350
  Common stock, $.30 par value;
   25,000,000 shares authorized;
   2,285,318 and 2,204,130 shares issued

   in 1999 and 1998, respectively                       685,595       661,239
  Additional paid-in capital                          5,367,358     4,939,287
  Accumulated deficit                                (3,459,777)    1,386,706)
  Treasury stock, at cost (31,944

   shares in 1999 and 1998)                            (215,314)     (215,314)
                                                      ---------     ---------
                                                      3,493,612     5,127,856

                                                      ---------     ---------
                                                    $ 7,208,900   $ 9,266,286
                                                      =========     =========


</TABLE>







        The accompanying notes are an integral part of these statements

                                                       6


<PAGE>

<TABLE>


                               TGC Industries, Inc.

                            STATEMENTS OF OPERATIONS

                             Years ended December 31,

                                                       1999            1998

<CAPTION>
<S>                                                 <C>           <C>
Revenue                                             $ 4,600,708   $17,073,506

Cost and expenses

 Cost of services                                     5,201,342    13,818,972
 Selling, general and administrative                    878,940     1,160,228
 Interest expense                                       202,497       261,480
 Debt financing costs                                   391,000            -
                                                      ---------     ---------
                                                      6,673,779    15,240,680

        Income (loss) from operations

        before income taxes                          (2,073,071)    1,832,826

Income tax expense (benefit)

 Current                                                     -         33,224
 Deferred                                                    -        (32,000)
                                                      ---------     ---------
                                                             -          1,224
                                                      ---------     ---------

        Net earnings (loss)                          (2,073,071)    1,831,602

Less dividend requirements on preferred stock          (446,300)     (451,740)
                                                      ---------     ---------

        Earnings (loss) allocable to

        common stockholders                         $(2,519,371) $  1,379,862
                                                      =========     =========
Earnings (loss) per common share

 Basic                                                   $(1.13)         $.64
 Diluted                                                 $(1.13)         $.38

Weighted average number of common shares

 Basic                                                2,228,989     2,166,503
 Diluted                                              2,228,989     4,789,015

</TABLE>





        The accompanying notes are an integral part of these statements

                                                       7


<PAGE>


<TABLE>

                              TGC Industries, Inc.

                        STATEMENT OF STOCKHOLDERS' EQUITY

                                                           Additional

                    Preferred stock       Common stock      paid-in

                   Shares      Amount    Shares    Amount   capital

                   ------      ------    ------  ---------- -----------
Balances at

<S>     <C>        <C>       <C>        <C>       <C>      <C>
January 1, 1998    1,129,350 $1,129,350 2,190,629 $657,189 $5,377,076
Issuance of
stock warrants            -          -         -        -       2,813
Exercise of stock
options and warrants      -          -     13,501    4,050     11,138
Dividends on preferred
stock ($.40 per share)    -          -         -        -    (451,740)

Net earnings              -          -         -        -          -
Balances at
December 31, 1998  1,129,350  1,129,350 2,204,130  661,239  4,939,287
Issuance of
common stock              -          -     47,827   14,348     33,479
Conversion of
preferred stock      (13,600)   (13,600)   33,361   10,008      3,592
Stock warrants
issued with debt          -          -         -        -     391,000
Net loss                  -          -         -        -          -
- ---------  -------  ---------   ---------    -------   ---------
Balances at

December 31, 1999  1,115,750 $1,115,750 2,285,318 $685,595 $5,367,358
                   =========  ========= =========  =======  =========

</TABLE>







                              TGC Industries, Inc.
<TABLE>

                        STATEMENT OF STOCKHOLDERS' EQUITY

                                   (Continued)

<CAPTION>
                                           Accumulated  Treasury
                                            deficit       stock         Total

                                           -----------   --------       ------

Balances at

<S>     <C>                                <C>          <C>         <C>
January 1, 1998                            $(3,218,308) $(215,314)  $ 3,729,993

Issuance of

stock warrants                                     -          -           2,813

Exercise of stock

options and warrants                               -          -          15,188

Dividends on preferred

stock ($.40 per share)                             -          -        (451,740)

Net earnings                                 1,831,602        -       1,831,602
                                             ---------    -------     ---------
Balances at

December 31, 1998                           (1,386,706)  (215,314)    5,127,856

Issuance of

common stock                                       -          -          47,827

Conversion of

preferred stock                                    -          -              -

Stock warrants

issued with debt                                   -          -         391,000

Net loss                                     (2,073,071)      -      (2,073,071)
                                              ---------    -------    ---------
Balances at

December 31, 1999                           $(3,459,777) $(215,314)$  3,493,612
                                              =========    =======    =========

         The accompanying notes are an integral part of these statements
</TABLE>

                                 8


<PAGE>



                      TGC Industries, Inc.
<TABLE>

                    STATEMENTS OF CASH FLOWS

                    Years ended December 31,

                                                      1999            1998
                                                    --------       --------
Cash flows from operating activities

<S>                                               <C>            <C>
  Net earnings (loss)                             $(2,073,071)   $ 1,831,602
  Adjustments to reconcile net earnings
   (loss) to net cash provided by
   operating activities

     Depreciation and amortization                  1,885,313      1,778,454
     Loss (gain) on disposal of property
       and equipment                                   (9,894)         4,487
     Deferred income taxes                                 -         (32,000)
     Debt financing costs                             391,000             -
  Changes in operating assets and liabilities

    Trade accounts receivable                       1,113,185      1,388,697
    Billings in excess of costs and
      estimated earnings on

      uncompleted contracts                          (387,474)    (1,838,237)
    Prepaid expenses                                   81,940          8,210
    Other assets                                          468         34,269
    Accounts payable                                 (525,373)      (834,363)
    Accrued liabilities                               (46,485)      (106,820)
    Federal income taxes payable                      (25,191)        25,191
                                                      -------      ---------
      Net cash provided by operating activities       404,418      2,259,490

Cash flows from investing activities

  Capital expenditures                                 (9,223)      (376,363)
  Proceeds from sale of property and equipment         46,300          3,400

                                                      -------      ---------
      Net cash provided by (used in)

       investing activities                            37,077       (372,963)

Cash flows from financing activities

  Dividends paid                                     (178,043)      (225,870)
  Net borrowings under line of credit                (290,000)       290,000
  Proceeds from issuance of debt                    3,112,500             -
  Principal payments of debt obligations           (1,890,277)    (1,386,194)
  Other                                                    -          18,001
                                                      -------      ---------
      Net cash provided by (used in)

       financing activities                           754,180     (1,304,063)

      Net increase in cash and cash equivalents     1,195,675        582,464

Cash and cash equivalents at beginning of year        702,999        120,535
                                                    ---------      ---------
Cash and cash equivalents at end of year           $1,898,674     $  702,999
                                                    =========       ========


                                                       9
</TABLE>


<PAGE>



<TABLE>
                            TGC Industries, Inc.

                   STATEMENTS OF CASH FLOWS -  CONTINUED

                           Years ended December 31,

                                                 1999         1998

<CAPTION>
Supplemental cash flow information

<S>                                        <C>             <C>
  Interest paid                            $    192,462    $  247,931
  Income taxes paid                        $     22,000    $    8,033

Noncash investing and financing activities

  During 1998, the Company  financed the acquisition of equipment  through notes
  payable of $778,131.

  During 1999,  the Company  issued  47,827  shares of common stock to preferred
  stockholders electing to receive common stock in lieu of cash dividends.

       The accompanying notes are an integral part of these statements

                                                       10
</TABLE>


<PAGE>



                             TGC Industries, Inc.

                         NOTES TO FINANCIAL STATEMENTS

                          December 31, 1999 and 1998

NOTE A - NATURE OF OPERATIONS

  TGC  Industries,  Inc.  (TGC  or the  Company)  is  engaged  in  the  domestic
  geophysical services business and primarily conducts seismic surveys and sells
  gravity data to companies engaged in exploration in the oil and gas industry.

NOTE B - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

  Cash Equivalents

  The Company  considers all highly liquid  investments  with original  maturity
  dates of three months or less to be cash equivalents.

  Property and Equipment

  Property and equipment are stated at cost.  Depreciation  and amortization are
  provided using the straight-line method over the estimated useful lives of the
  individual assets.

  Long-Lived Assets

  Long-lived  assets held and used by the Company are  reviewed  for  impairment
  whenever events or changes in circumstances  indicate that the carrying amount
  of an  asset  may not be  recoverable.  For the  purposes  of  evaluating  the
  recoverability  of long-lived  assets,  the  recoverability  test is performed
  using undiscounted cash flows estimated to be generated by those assets.

  Income Taxes

  Deferred income taxes reflect the impact of temporary  differences between the
  amounts of assets and liabilities  recognized for financial reporting purposes
  and such amounts recognized for tax purposes.

  Stock-Based Compensation

  Statement of Financial  Accounting  Standards No. 123 (SFAS 123),  "Accounting
  for Stock-Based Compensation" encourages,  but does not require,  companies to
  record compensation cost for stock-based  employee  compensation plans at fair
  value.  The  Company  has  chosen  to  continue  to  account  for  stock-based
  compensation  using  the  intrinsic  value  method  prescribed  in  Accounting
  Principles Board Opinion No. 25 (APB 25),

                                                       11


<PAGE>



                             TGC Industries, Inc.

                         NOTES TO FINANCIAL STATEMENTS

                          December 31, 1999 and 1998

NOTE B - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Continued

 "Accounting  for Stock Issued to Employees" and provides the required pro forma
  disclosures prescribed by SFAS 123.

  Revenue Recognition

  Revenues from  conducting  seismic surveys are recognized over the term of the
  contract  using  the  percentage-of-completion   method.  Under  this  method,
  revenues are recognized on the  units-of-production  method.  Revenues for the
  sale of gravity data are recognized when services are rendered.

  Earnings (Loss) Per Share

  Basic  earnings  (loss) per common  share is based upon the  weighted  average
  number of shares of common  stock  outstanding.  Diluted  earnings  (loss) per
  share is based upon the weighted  average number of common shares  outstanding
  and, when dilutive,  common shares  issuable for stock  options,  warrants and
  convertible securities.

  Use of Estimates

  The preparation of financial  statements in conformity with generally accepted
  accounting  principles  requires  management to make estimates and assumptions
  that affect the reported  amounts of assets and  liabilities and disclosure of
  contingent assets and liabilities at the date of the financial  statements and
  the reported  amounts of revenues and expenses  during the  reporting  period.
  Actual results could differ from those estimates.

NOTE C - COSTS AND ESTIMATED EARNINGS ON UNCOMPLETED CONTRACTS

  The components of uncompleted contracts are as follows:
<TABLE>

                                                         December 31,
                                                      1999         1998

                                                     ------       ------
     Costs incurred on uncompleted contracts and

<S>                                                <C>          <C>
         estimated earnings                        $     -      $1,511,088
     Less billings to date                               -       1,898,562
                                                     ------      ---------
                                                   $     -     $  (387,474)
                                                     ======      =========
</TABLE>


                                                       12


<PAGE>



                             TGC Industries, Inc.

                         NOTES TO FINANCIAL STATEMENTS

                          December 31, 1999 and 1998

NOTE C - COSTS AND ESTIMATED EARNINGS ON UNCOMPLETED CONTRACTS  -
         Continued

  These  components  are included in the  accompanying  balance  sheet under the
  following captions:
<TABLE>

                                                         December 31,
                                                      1999         1998

                                                     ------       ------

     Costs and estimated earnings in excess of

<S>                                                 <C>         <C>
         billings on uncompleted contracts          $     -     $ 144,972
     Billings in excess of costs and estimated
         earnings on uncompleted contracts                -      (532,446)
                                                      ------      -------

                                                    $     -     $(387,474)
</TABLE>
                                                      ======      =======

NOTE D - ACCRUED LIABILITIES
<TABLE>

  Accrued liabilities consist of the following:

                                                         December 31,
                                                      1999         1998

                                                     ------       ------

<S>                                                  <C>        <C>
     Compensation and payroll taxes                  $13,387    $  39,800
     Dividends payable                                    -       225,870
     Insurance                                            -        26,686
     Other                                            46,975       40,361
                                                      ------      -------

                                                     $60,362     $332,717

                                                      ======      =======
</TABLE>


                                                       13


<PAGE>



                             TGC Industries, Inc.

                         NOTES TO FINANCIAL STATEMENTS

                          December 31, 1999 and 1998

NOTE E - DEBT
<TABLE>

  Long-term Obligations

  Long-term obligations consist of the following:

                                                          December 31,
                                                      1999           1998

                                                    --------      ---------
  Debenture payable to a corporation, maturing
    in December 2009, interest at 8.5%, payable

<S>                                              <C>            <C>
    semi-annually                                $2,500,000     $        -
  Note payable, interest at 4%, due in monthly
    installments of $552 including interest;
    collateralized by equipment and accounts

    receivable                                      108,342         110,452
  Note payable, interest at 4%, due in monthly
    installments of $1,130 including interest;
    collateralized by equipment and accounts

    receivable                                       40,923          52,357
  Notes payable to a finance company, interest
    at 11%, due in monthly installments of
    $50,267 including interest; collateralized

    by equipment                                    432,458         786,957
  Note payable to a bank, interest at 9.83%, due
    in monthly installments of $22,959
    including interest; collateralized by

    equipment and accounts receivable                    -          264,360
  Note  payable to a finance company, interest at
    9.5%, due in monthly installments of $5,143
    including interest; collateralized by

    equipment                                        90,666         127,107
  Note payable to a finance company, interest at
    8.7%, due in monthly installments of $5,038
    including interest; collateralized by

    equipment                                        98,079         133,887
  Note  payable to a finance company, interest at
    8.8%, due in monthly installments of $4,974
    including interest; collateralized by

    equipment                                       109,539         144,788
  Note  payable to a finance company, interest at
    9.4%, due in monthly installments of  $12,104
    including interest, collateralized by
    equipment                                       223,987         309,436
  Capital lease obligations, interest rates ranging
    from 10% to 13%                                      -          452,427
                                                  ---------         -------
                                                 $3,603,994      $2,381,771

</TABLE>
                                                  =========       =========


                                                       14


<PAGE>



                             TGC Industries, Inc.

                         NOTES TO FINANCIAL STATEMENTS

                          December 31, 1999 and 1998

NOTE E - DEBT - Continued

   Aggregate  maturities  of long-term  obligations  at December 31, 1999 are as
   follows:

      Year ending
<TABLE>
      December 31,

      ------------

<S>     <C>                                   <C>
        2000                                  $   739,468
        2001                                      244,225
        2002                                       15,475
        2003                                        5,854
        2004                                        2,594
        Thereafter                              2,596,378
                                                ---------
                                                3,603,994

          Less current maturities                 739,468

                                                ---------

                                               $2,864,526

</TABLE>
                                                =========


  Subordinated Debt

  During 1999,  the Company  issued  subordinated  notes  payable of $312,500 to
  officers and directors. The notes payable bore interest at 8% and were paid in
  full during December 1999.

  On December 14, 1999, the Company issued a $2,500,000 convertible subordinated
  debenture to a  corporation.  The debenture  bears  interest at 8.5%,  payable
  semi-annually,   and  matures  in  December  2009.   The  debenture,   at  the
  corporation's  option,  may be converted into either preferred stock or common
  stock at a conversion price of $1.15 per share.

  Capital Lease Obligations

  Outstanding  capital  leases at December 31,  1998,  matured in April 1999 and
  October  1999.  Property  under  capital  leases at  December  31,  1998,  was
  $1,732,066 less accumulated depreciation of $463,552.

                                                       15


<PAGE>



                             TGC Industries, Inc.

                         NOTES TO FINANCIAL STATEMENTS

                          December 31, 1999 and 1998

  NOTE E - DEBT - Continued

  Line of Credit

  At December 31, 1998, the Company had $290,000  outstanding  under a revolving
  $1,000,000 bank line of credit which matured during November 1999.

  The fair value of debt  obligations is estimated  using  discounted cash flows
  based  on the  Company's  incremental  borrowing  rate  for  similar  types of
  borrowings.  A  comparison  of the  carrying  value  and  fair  value of these
  instruments is as follows:
<TABLE>

                                                         December 31,
                                                    1999              1998

                                                   -------          -------

<S>                                               <C>             <C>
    Carrying value                                $3,603,994      $2,671,771
    Fair value                                    $3,264,899      $2,602,828
</TABLE>

NOTE F - STOCKHOLDERS' EQUITY

  Common Stock Split

  On November 5, 1998, the Board of Directors  declared a one-for- three reverse
  stock split on the Company's common stock.  Common stock as of January 1, 1998
  has been restated to reflect this reverse  split.  All references to number of
  shares,  except  shares  authorized,  and  to  per  share  information  in the
  financial  statements have been adjusted to reflect the reverse stock split on
  a retroactive basis.

  Earnings Per Share

  A reconciliation  of the numerators and denominators of the basic earnings per
  common share and diluted earnings per common share for the year ended December
  31, 1998 is as follows:

                                                       16


<PAGE>



                             TGC Industries, Inc.

                         NOTES TO FINANCIAL STATEMENTS

                          December 31, 1999 and 1998

NOTE F - STOCKHOLDERS' EQUITY - Continued
<TABLE>

                                                                  Per share

<CAPTION>
                                            Income        Shares    amount

    Net earnings                          $1,831,602
      Less dividend requirements on
      preferred stock                       (451,740)

                                           ---------
    Basic earnings per common share
      Income allocable to common

<S>                                        <C>           <C>          <C>
      stockholders                         1,379,862     2,166,503    $.64
                                                                        ==
    Effect of dilutive securities

      Stock options                                          3,592
      Warrants                                             109,253
      Convertible preferred stock            451,740     2,509,667
                                           ---------     ---------
    Diluted earnings per common share
      Income allocable to common

       stockholders plus assumed

       conversions                        $1,831,602     4,789,015    $.38
                                           =========     =========      ==
</TABLE>

  Stock-Based Compensation Plans

  The  Company's  1986  Incentive  Stock Option Plan (the "1986  Plan")  expired
  during July 1997. At December 31, 1999,  options  covering 6,335 shares of the
  Company's common stock were outstanding  under the 1986 Plan.  Options granted
  under the 1986 Plan  must be  exercised  within  five  years  from the date of
  grant.  All options were  exercisable  at December  31, 1999,  and will remain
  outstanding until they are exercised or canceled.

                                                       17


<PAGE>



                             TGC Industries, Inc.

                         NOTES TO FINANCIAL STATEMENTS

                          December 31, 1999 and 1998

NOTE F - STOCKHOLDERS' EQUITY - Continued

  The Company currently has in effect a 1993 Stock Option Plan (the "1993 Plan")
  covering a total of 283,334  shares of the  Company's  common  stock.  Options
  under the 1993 Plan must be granted  at prices not less than the market  price
  at the date of grant and must be exercised  within five years from the date of
  grant.  Options  covering  45,004  shares  are  exercisable  as  follows:  (i)
  one-third of the shares after the first twelve-month period following the date
  of grant,  (ii) up to  two-thirds  of the shares  after the first  twenty-four
  month period following the date of grant, and (iii) all of the shares of stock
  subject  to the  option at any time after the first  thirty-six  month  period
  following the date of grant. Options covering 35,000 shares are exercisable as
  follows:  (i) one-third of the shares on January 1, 1999,  and (ii) all of the
  shares after January 1, 2000.  Options  covering 37,100 shares are exercisable
  as follows:  (i)one-third on October 21, 2000, and(ii) of the all shares after
  October 21, 2001. At December 31, 1999,  outstanding options for 68,337 shares
  were exercisable.

  In  conjunction  with the spin-off of the Company's  wholly-owned  subsidiary,
  Chase Packaging  Corporation  (Chase),  in 1996,  options held by employees of
  Chase under the 1993 Plan were  converted into a  nonqualified  plan.  Options
  covering 53,058 shares were outstanding and exercisable at December 31, 1999.

  The  Company has  adopted  only the  disclosure  provisions  of SFAS 123.  The
  Company  will  continue  to  apply  APB  25  and  related  interpretations  in
  accounting for its stock-based  compensation  plans. Had compensation cost for
  the  Company's  stock  grants been  determined  consistent  with SFAS 123, the
  Company's  net earnings  (loss) and net  earnings  (loss) per common share for
  1999 and 1998 would approximate the pro forma amounts indicated below:
<TABLE>

                                     1999                      1998
                          As reported    Pro forma    As reported  Pro forma

                          -----------    ---------    -----------  ---------
<S>                       <C>           <C>           <C>         <C>
  Net earnings (loss)     $(2,073,071)  $(2,093,544)  $1,831,602  $1,780,453
                            =========     =========    =========   =========
  Net earnings (loss)
    allocable to

    common stockholders   $(2,519,371)  $(2,539,844)  $1,379,862  $1,362,475
                            =========     =========    =========   =========
  Earnings (loss)
    per common share

       Basic                   $(1.13)       $(1.14)        $.64         $.63
       Diluted                 $(1.13)       $(1.14)        $.38         $.37


</TABLE>
                                                       18


<PAGE>




                             TGC Industries, Inc.

                         NOTES TO FINANCIAL STATEMENTS

                          December 31, 1999 and 1998

NOTE F - STOCKHOLDERS' EQUITY - Continued

  The  effects  of  applying  SFAS  123 in this  pro  forma  disclosure  are not
  indicative  of future  disclosures  because  they do not take into  effect pro
  forma  compensation  expense  related to grants made before December 31, 1994.
  The fair value of these  options was  estimated at the date of grant using the
  Black-Scholes   option-pricing  model  with  the  following  weighted  average
  assumptions used for grants:  expected volatility of 143% and 135% in 1999 and
  1998, respectively; risk-free interest rate of 6.4% and 5.4% in 1999 and 1998,
  respectively;  and  expected  life of 5 years for 1999 and 1998.  The weighted
  average fair value of options  granted during 1999 and 1998 was $.68 and $.70,
  respectively.

  The following table summarizes activity under the Plans:
<TABLE>

                                                                  Weighted
                                                  Shares under     average

                                                     option     exercise price

<S>                   <C>                            <C>           <C>
   Balance at January 1, 1998                        125,400       $2.79
     Granted                                          35,000        1.00
     Exercised                                        (1,000)       1.13
     Canceled                                         (5,002)       3.00
                                                       -----
   Balance at December 31, 1998                      154,398        2.39
     Granted                                          37,100         .75
     Canceled                                        (15,001)       3.87

   Balance at December 31, 1999                      176,497       $1.92
                                                     =======        ====
   Exercisable at December 31:

     1998                                             99,398       $2.78
     1999                                            127,730       $2.34
</TABLE>

  The following information applies to options outstanding at December 31, 1999:
<TABLE>

                                         Weighted
                                          average

                                         remaining     Weighted

           Range of        Number        contractual    average
       exercise prices   outstanding       life      exercise price

       ---------------   -----------     ----------- --------------
<S>      <C>    <C>       <C>                <C>        <C>
         $.75 - 1.13      78,435             4.2        $  .89
         $2.40 - 3.00     98,062             1.4          2.74
                         -------
                         176,497                        $ 1.92
                         =======                          ====

</TABLE>

                                                       19


<PAGE>



                             TGC Industries, Inc.

                         NOTES TO FINANCIAL STATEMENTS

                          December 31, 1999 and 1998

NOTE F - STOCKHOLDERS' EQUITY - Continued

  The following information applies to options exercisable at December 31, 1999:
<TABLE>

          Range of              Number          Weighted average
       exercise prices       exercisable         exercise price

<S>      <C>     <C>            <C>                  <C>
         $1.00 - 1.13           29,668               $1.03
         $2.40 - 3.00           98,062                2.74
                               -------
                               127,730               $2.34
</TABLE>
                               =======                ====
  Stock Warrants

  At December 31, 1999, warrants covering 1,136,574 shares were outstanding.  In
  connection  with the  issuance of  subordinated  notes  payable  during  1999,
  certain officers and directors  received warrants covering 850,000 shares with
  a value of $391,000.  These warrants have a strike price of $.30 and expire on
  July 31, 2009.  Warrants  covering 233,240 shares have a strike price of $1.13
  per share and expire on December 31, 2000.  Warrants  covering  50,000  shares
  have a strike  price of $2.40 and expire on  December  27,  2000.  Warrants to
  purchase  3,334  common  shares  have a strike  price of $3.19  and  expire on
  January 25, 2001.

  Preferred Stock

  During 1996,  the Company issued  1,150,350  shares of Series C 8% convertible
  exchangeable  preferred  stock  at $5.00  per  share  in a  private  placement
  offering with gross proceeds of approximately $5,800,000.  The preferred stock
  is,  at  the  option  of  the  Company,   exchangeable  into  8%  subordinated
  convertible  debentures.  The preferred  stock and debentures are  convertible
  into shares of the Company's common stock at the conversion price of (i) $2.00
  per share if exercised by December 31, 2001, (ii) $3.75 per share if exercised
  from  January 1, 2002 through  December  31,  2002,  and (iii) $6.00 per share
  thereafter.

  Dividends

  Holders of the Company's Series C 8% convertible  exchangeable preferred stock
  will  receive,  when,  as and if  declared  by the Board of  Directors  of the
  Company,  dividends  at a rate of 8% per  annum.  The  dividends  are  payable
  semi-annually  during  January and July of each year.  At December  31,  1999,
  cumulative dividends of approximately $446,000 were in arrears.

                                                       20


<PAGE>



                             TGC Industries, Inc.

                         NOTES TO FINANCIAL STATEMENTS

                          December 31, 1999 and 1998

NOTE G - INCOME TAXES

  The income tax  provision  (benefit)  reconciled  to the tax  computed  at the
  statutory Federal rate is as follows:
<TABLE>

                                                            Years ended
                                                            December 31,

                                                          1999        1998

<S>                                                   <C>          <C>
    Federal tax expense (benefit) at statutory rate   $(704,844)   $ 623,161
    Meals and entertainment                               5,512        4,100
    Other                                               (41,298)       9,548
    Change in valuation allowance                       740,630     (635,585)
                                                        -------      -------
                                                      $      -     $   1,224
                                                        =======      =======


  Deferred tax assets and liability consist of the following:

                                                            December 31,
                                                          1999        1998

    Deferred tax assets

      Net operating loss carryforwards               $1,904,159   $1,208,233
      Other                                              33,046       47,864
    Deferred tax liability

      Property and equipment                           (729,981)    (789,503)
                                                      ---------      -------
                                                      1,207,224      466,594

      Less valuation allowance                       (1,005,224)    (264,594)
                                                      ---------      -------

      Net deferred tax asset                        $   202,000  $   202,000
                                                      =========      =======
</TABLE>

  At December 31, 1999,  the Company had net  operating  loss  carryforwards  of
  approximately  $5,600,000  available to offset future  taxable  income,  which
  expire at  various  dates  through  2019.  Future  tax  benefits,  such as net
  operating loss carryforwards, are recognized to the extent that realization of
  such benefits are more likely than not.

                                                       21


<PAGE>



                             TGC Industries, Inc.

                         NOTES TO FINANCIAL STATEMENTS

                          December 31, 1999 and 1998

NOTE H - 401(k) PLAN

  The Company has a 401(k)  salary  deferral plan which covers all employees who
  have  reached the age of 20.5 years and have been  employed by the Company for
  at least one year. The covered  employees may elect to have an amount deducted
  from their wages for  investment  in a  retirement  plan.  The  Company  makes
  contributions to the plan equal to 100% of each participant's salary reduction
  contributions to the plan up to 2% and 4.75% of the participant's compensation
  in 1999 and 1998,  respectively.  The Company's  matching  contribution to the
  plan was  approximately  $13,000 and $44,000 for the years ended  December 31,
  1999 and 1998, respectively.

NOTE I - CONCENTRATION OF CREDIT RISK

  The Company sells its geophysical  services primarily to large independent oil
  and gas companies operating in the United States. The Company performs ongoing
  credit  evaluations of its  customer's  financial  condition  and,  generally,
  requires no collateral from its customers. At December 31, 1998, two customers
  accounted for approximately 99% of accounts receivable.

  During 1999, three customers accounted for 38%, 20% and 16% of the revenues of
  the Company,  respectively.  During 1998,  three customers  accounted for 24%,
  22%, and 17% of the revenues of the Company, respectively.

NOTE J - CONTINGENCIES

  In conducting its activities,  the Company from time to time is the subject of
  various claims arising from the ordinary course of business. In the opinion of
  management,  the ultimate  resolution of such claims is not expected to have a
  material adverse effect upon the financial position of the Company.

NOTE K - FOURTH QUARTER ADJUSTMENT

  During the fourth  quarter of fiscal  1999,  the Company  recorded a charge to
  earnings  of  $391,000  for an  adjustment  related  to debt  financing  costs
  incurred in connection  with the issuance of debt  securities  with detachable
  stock warrants.

                                                       22


<PAGE>


ITEM 8. CHANGES IN AND DISAGREEMENTS WITH ACCOUNTANTS ON
        ACCOUNTING AND FINANCIAL DISCLOSURE

     Not Applicable.

                                  PART III

ITEM 9. DIRECTORS, EXECUTIVE OFFICERS, PROMOTER AND CONTROL
        PERSONS, COMPLIANCE WITH SECTION 16(a) OF THE EXCHANGE

        ACT.

     Certain  information  required  by  Item 9 of the  Form  10-KSB  is  hereby
incorporated by reference from the Company's  definitive proxy statement,  which
will be filed  pursuant to  Regulation  14A within 120 days after the  Company's
year end for the year covered by this report,  under the caption  "Nominees  for
Directors" in the proxy statement.

ITEM 10. EXECUTIVE COMPENSATION.

     The information  required by Item 10 of Form 10-KSB is hereby  incorporated
by reference from the Company's definitive proxy statement,  which will be filed
pursuant to Regulation  14A within 120 days after the Company's year end for the
year covered by this report,  under the  caption"Executive  Compensation" in the
proxy statement.

ITEM 11. SECURITY OWNERSHIP OF CERTAIN BENEFICIAL OWNERS AND
         MANAGEMENT.

     The information  required by Item 11 of Form 10-KSB is hereby  incorporated
by reference from the Company's definitive proxy statement,  which will be filed
pursuant to Regulation  14A within 120 days after the Company's year end for the
year covered by this  report,  under the  caption"Security  Ownership of Certain
Beneficial Owners and Management" in the proxy statement.

ITEM 12. CERTAIN RELATIONSHIPS AND RELATED TRANSACTIONS.

     The information  provided by Item 12 of Form 10-KSB is hereby  incorporated
by reference from the Company's definitive proxy statement,  which will be filed
pursuant to Regulation  14A within 120 days after the Company's year end for the
year covered by this report, under the caption"Transactions  with Management" in
the proxy statement.

ITEM 13.  EXHIBITS.

Item 13 (a). The following is a list of exhibits to this Form 10-KSB:

                3.1   Restated  Articles of  Incorporation  as of July 31, 1986,
                      filed  as  Exhibit  3(a)  to  the  Company's  Registration
                      Statement on Form 10  (Registration  No.  0-14908),  filed
                      with the Commission and incorporated herein by reference.

                3.2   Certificate   of  Amendment  to  the  Company's   Restated
                      Articles of  Incorporation,  as of July 5, 1988,  filed as
                      Exhibit 3.2 to the  Company's  Annual  Report on Form 10-K
                      for  the  fiscal  year  ended   December  31,  1988,   and
                      incorporated herein by reference.

                3.3   Restated Articles of Incorporation  (with amendment) as of
                      November 6, 1998,  filed as Exhibit  3.3 to the  Company's
                      Annual  Report on Form  10-KSB for the  fiscal  year ended
                      December 31, 1998, and incorporated herein by reference.

                3.4   First Amended  Bylaws of the Company as amended,  filed as
                      Exhibit 3.2 to the  Company's  annual  report on Form 10-K
                      for  the  fiscal  year  ended   December  31,  1987,   and
                      incorporated herein by reference.

                3.5   Amendment to the Company's First Amended Bylaws as adopted
                      by the Board of Directors on March 7, 1988,
                      filed as Exhibit 3.3 to the Company's Annual Report
                      on Form 10-K for the fiscal year ended December 31,
                      1987, and incorporated herein by reference.

                4.1   Statement of Resolution Establishing Series of
                      Preferred Stock of TGC Industries, Inc. filed with
                      the Secretary of State of Texas on July 16, 1993,
                      filed as Exhibit 2 to the Company's Current Report on
                      Form 8-K dated August 11, 1993, and incorporated
                      herein by reference.

                4.2   Statement   of   Resolution   Establishing   Series  C  8%
                      Convertible    Exchangeable   Preferred   Stock   of   TGC
                      Industries,  Inc. as filed with the  Secretary of State of
                      Texas on July 9, 1996, filed as Exhibit B to the Company's
                      current report on Form 8-K dated July 11,
                      1996, filed with the Commission and incorporated
                      herein by reference.

                4.3   Statement   of   Resolution   Establishing   Series  C  8%
                      Convertible    Exchangeable   Preferred   Stock   of   TGC
                      Industries,  Inc. as filed with the  Secretary of State of
                      Texas on December 30, 1998.

                4.4   Form of Debenture Agreement and Debenture for 8%
                      Subordinated Convertible Debentures, Series A, filed
                      as Exhibit 4.2 to the Company's Registration
                      Statement on Form SB-2 (Registration No. 333-12269),
                      as amended, filed with the Commission and incorporated
                      herein by reference.

                4.5   Form of Warrant Agreement dated July 28, 1995, as amended,
                      and  Warrant,  filed  as  Exhibit  4.3  to  the  Company's
                      Registration  Statement  on Form  SB-2  (Registration  No.
                      333-12269),  as  amended,  filed with the  Commission  and
                      incorporated herein by reference.

                4.6   Debenture  Agreement dated December 10, 1999, with respect
                      to   the   Company's   $2,500,000   8   1/2%   Convertible
                      Subordinated  Debenture,  Series B payable to Wedge Energy
                      Services, L.L.C.

               10.1   Service Mark License  Agreement dated as of July 31, 1986,
                      between the Company and Supreme Industries, Inc. (formerly
                      ESI  Industries,   Inc.),  relating  to  the  use  of  the
                      Company's  logo,  filed as Exhibit  10(b) to the Company's
                      Registration Statement on Form 10
                      (Registration No. 0-14908), filed with the Commission
                      and incorporated herein by reference.

               10.2   The Company's 1986 Incentive and Nonqualified Stock Option
                      Plan, filed as Exhibit 10(c) to the Company's Registration
                      Statement on Form 10  (Registration  No.  0-14908),  filed
                      with the Commission and incorporated herein by reference.

               10.3   Amendment  Number One to the Company's  1986 Incentive and
                      Nonqualified  Stock Option Plan as adopted by the Board of
                      Directors  on May 1, 1987,  filed as  Exhibit  10.4 to the
                      Company's  annual  report on Form 10-K for the fiscal year
                      ended  December  31,  1987,  and  incorporated  herein  by
                      reference.

               10.4   The Company's 1993 Stock Option Plan as adopted by
                      the Board of Directors on June 3, 1993, filed as
                      Exhibit 10.4 to the Company's Registration Statement
                      on Form S-2 (Registration No. 33-73216), filed
                      with the Commission and incorporated by reference.

               10.5   Master Contract for Geophysical Services-Onshore
                      dated April 18, 1990 between Marathon Oil Co. and the
                      Company together with a form of Supplementary
                      Agreement thereto, filed as Exhibit 10.8 to the
                      Company's Registration Statement on Form S-2
                      (Registration No. 33-73216), filed with the
                      Commission and incorporated herein by reference.

               10.6   Agreement  for  Spin-off  of  Subsidiary  Stock  filed  as
                      Exhibit 1 to the Company's Form 8-K filed with the
                      Commission on August 9, 1996 and incorporated herein
                      by reference.

               10.7   Bill of Sale dated July 31, 1996  between TGC  Industries,
                      Inc.  and Chase  Packaging  Corporation,  filed as Exhibit
                      10.8 to the Company's annual report on Form 10-KSB for the
                      fiscal year ended  December  31,  1996,  and  incorporated
                      herein by reference.

               10.8   Amendment  No. 1 to the 1993 Stock  Option Plan as adopted
                      by the  Board  of  Directors  on July 24,  1996,  filed as
                      Exhibit 10.9 to the Company's Annual Report on Form 10-KSB
                      for  the  fiscal  year  ended   December  31,  1998,   and
                      incorporated herein by reference.

               10.9   Amendment No. 2 to the 1993 Stock Option Plan as adopted
                      by the Board of Directors and approved by Company's
                      Shareholders on June 4, 1998, filed as Exhibit 10.10 to
                      the Company's Annual Report on Form 10-KSB for the
                      fiscal year ended December 31, 1998, and incorporated
                      herein by reference.

               10.10  Warrant Agreements and Warrant Certificates dated July 30,
                      1999 issued by the Company to JMS Inc. Cust FBO William J.
                      Barrett Keogh, JMS Inc. Cust FBO Herbert M. Gardner Keogh,
                      Edward L. Flynn,  Allen T. McInnes,  and Wayne A. Whitener
                      in  connection  with the  issuance by the Company of notes
                      payable to such persons.

               10.11  Debenture  Purchase  Agreement  dated  December  10, 1999,
                      between WEDGE Energy Services, L.L.C. and the Company with
                      respect to the  purchase by WEDGE of the  Company's 8 1/2%
                      Convertible Subordinated Debenture, Series B, for the cash
                      consideration of $2,500,000 paid by WEDGE to the Company.

               10.12  Voting  Agreement  dated  December 10,  1999,  between the
                      Company, WEDGE Energy Services,  L.L.C., and the following
                      shareholders   of  the  Company:   Allen  McInnes,   Wayne
                      Whitener,  Herbert Gardner,  William J. Barrett and Edward
                      L. Flynn.

               10.13  The  Company's  1999 Stock  Option  Plan as adopted by the
                      Board of Directors on December 14, 1999.

               27.    Financial Data Schedule.

                                SIGNATURES

In  accordance  with  Section 13 or 15(d) of the Exchange  Act,  the  registrant
caused this report to be signed on its behalf by the undersigned, thereunto duly
authorized.

                                         TGC INDUSTRIES, INC.

Date:  March 24, 2000                    By:/s/ WAYNE A. WHITENER
                                            President (Principal Executive
                                            Officer)

    In  accordance  with the Exchange  Act, this report has been signed below by
the following  persons on behalf of the  registrant and in the capacities and on
the dates indicated.

Date:  March 24, 2000             By:   /s/ALLEN T. McINNES

                                         Allen T. McInnes
                                         Chairman of the Board
                                         and Secretary

Date:  March 24, 2000             By:   /s/EDWARD L. FLYNN
                                         Edward L. Flynn
                                         Director


Date:  March 24, 2000             By:   /s/ WAYNE A. WHITNER
                                         Wayne A. Whitener
                                         President, Chief Executive
                                         Officer and Director


Date:  March 24, 2000             By:   /s/ KENNETH USELTON
                                         Kenneth Uselton
                                         (Principal Financial and
                                         Accounting Officer)


Date:  March 24, 2000             By:   /s/ WILLIAM J. BARRRETT
                                         William J. Barrett
                                         Director


Date:  March 24, 2000             By:   /s/ HERBERT M. GARDNER
                                         Herbert M. Gardner
                                         Director




                                                       23


<PAGE>










                              EXHIBIT 4.6

                          DEBENTURE AGREEMENT


<PAGE>



                                                                      12/10/99

                            DEBENTURE AGREEMENT

     8 1/2 % Convertible Subordinated Debenture, Series B Due December 1, 2009
                  Original Principal Amount $2,500,000

     THIS DEBENTURE AGREEMENT  (the"Agreement") is made and entered into on this
10th day of December,  1999, by and between  WEDGE Energy  Services,  L.L.C.,  a
Delaware limited liability company ("Holder") and TGC Industries,  Inc., a Texas
corporation (the"Company").

                                   R E C I T A L S

     WHEREAS  the  Company  is  issuing  this  8 1/2%  Convertible  Subordinated
Debenture,  Series B due  December 1, 2009 in the original  principal  amount of
$2,500,000  (the"Debenture" or the"Note")  pursuant to the payment of $2,500,000
cash by Holder to the Company and the Company is paying to Holder all  principal
and accrued  interest on that certain  Advance Note in the  principal  amount of
$300,000,  payable by Company to Holder dated November 1, 1999, and as set forth
in that  certain  Debenture  Purchase  Agreement  of  even  date  herewith  (the
"Purchase Agreement").

     WHEREAS  the  Company  is now  issuing  to the  Holder  and the  Holder  is
receiving such Debenture from the Company; and

     WHEREAS the parties  hereto wish to set forth the terms and  conditions  of
such Debenture;

     NOW,  THEREFORE,  in  consideration  of the  premises  and  of  the  mutual
agreements hereinafter set forth, the parties hereto agree as follows:

                               ARTICLE I

                              DEFINITIONS

     In addition to the terms defined elsewhere in this Agreement, the following
terms shall have the meanings set forth below:

     Section 1.01. Capitalized Lease. The term"Capitalized Lease" shall mean any
lease of real or personal  property  under which the rentals are  required to be
capitalized  for  financial  reporting  purposes in  accordance  with  generally
accepted accounting principles.

     Section 1.02.  Common Stock.  The term"Common  Stock" shall mean the Common
Stock, par value $.30 per share, of the Company.

     Section 1.03.  Conversion  Price.  The conversion price per share of Common
Stock,  Senior  Convertible  Preferred  Stock or Series D Convertible  Preferred
Stock into which the Debenture is  convertible,  which price is $1.15 per share,
as such  conversion  price may be adjusted and  readjusted  from time to time in
accordance with the terms of Section 8.05 hereof.

     Section 1.04.  Event of Default.  The term "Event of Default" shall mean an
Event of Default as defined in Section 9.01 hereof.

     Section  1.05   Indebtedness.   The   term"Indebtedness"   shall  mean  (a)
indebtedness  for money borrowed and deferred payment  obligations  representing
the unpaid purchase price of property or stock, other than normal trade credits,
which would be included in determining  total liabilities shown on the liability
side of a consolidated  balance sheet of the Company and its  Subsidiaries;  (b)
guarantees and  endorsements  of obligations of others,  directly or indirectly,
including  obligations under industrial revenue and pollution control bonds, and
all other repurchase agreements and indebtedness in effect guaranteed through an
agreement,  contingent  or  otherwise,  to  purchase  such  indebtedness,  or to
purchase or sell property,  or to purchase or sell  services,  primarily for the
purpose of enabling the debtor to make payment of the  indebtedness or to assure
the owner of the  indebtedness  against  loss,  or to supply  funds to or in any
manner  invest  in the  debtor,  or  otherwise  (but  excluding  guarantees  and
endorsements  of  notes,  bills  and  checks  made  in the  ordinary  course  of
business); (c) indebtedness secured by any mortgage,  lien, pledge,  conditional
sale  agreement,  title  retention  agreement,  or other  security  interest  or
encumbrance upon property owned by the Company, or its Subsidiaries, even though
such  indebtedness has not been assumed;  and (d) amounts due under  Capitalized
Leases as reflected on the balance sheet.

     Section 1.06. Interest Rate. The term"Interest Rate" shall mean an interest
rate payable on the  Debentures of 8 1/2% per annum and as set forth on the face
of the Debenture.

     Section 1.07. Issuance Date. The term"Issuance Date" shall mean the date of
issuance of the  Debenture of December 10, 1999, as set forth on the face of the
Debenture.

     Section 1.08. Maturity Date. The term"Maturity Date" shall mean December 1,
2009.

     Section  1.09.  Debenture.  The  term"Debenture"  shall mean the  Debenture
issued by the Company and concurrently herewith being acquired by the Holder, in
the form set forth on Exhibit"A"  attached hereto, as originally  executed or as
may from time to time be supplemented  or amended  pursuant to its provisions or
the provisions hereof. If the Holder purchases or otherwise becomes the owner of
more  than  one  Debenture,  the  term"Debentures"  shall  include  all  of  the
Debentures owned by the Holder taken as a whole. The term"Debentures" shall mean
all of the  Debentures  issued by the Company and governed by this Agreement and
other Debenture Agreements of like tenor.

     Section  1.10.   Person.   The  term"Person"   shall  mean  an  individual,
partnership, corporation, trust or unincorporated organization, and a government
or agency or political subdivision thereof.

     Section  1.11.  Senior   Convertible   Preferred  Stock  The  term  "Senior
Convertible  Preferred  Stock" shall mean that  certain  series of 8 1/2% Senior
Convertible  Preferred  Stock  as  described  in  Section  3.1 of  the  Purchase
Agreement.

     Section  1.12.  Series D  Convertible  Preferred  Stock The term  "Series D
Convertible  Preferred  Stock"  shall  mean that  certain  series of 8% Series D
Convertible  Preferred  Stock  as  described  in  Section  3.2 of  the  Purchase
Agreement.

     Section 1.13. Superior Indebtedness.  The term"Superior Indebtedness" shall
mean (a) Funded Debt,  being all  Indebtedness  having a final  maturity of more
than one year, and all guarantees of Indebtedness  extending more than one year,
from  its"date of origin" or which is renewable or  extendable  at the option of
the  obligor  for a period  or  periods  of more  than one year from its date of
origin,  and all amounts due under  Capitalized  Leases reflected on the balance
sheets;  and (b)  Current  Debt,  being  all  unsecured  Indebtedness  for money
borrowed,  payable on demand or having a maturity of not more than one year from
the date of determination (other than current maturities of Funded Debt) and not
extendable or renewable at the option of obligor.

     Section 1.14.  Subsidiary.  The term"Subsidiary" shall mean any corporation
of which more than 80% (by number of votes) of the voting  stock is owned by the
Company or another Subsidiary.

                                 ARTICLE II

                                THE DEBENTURE

     Section  2.01.  Debenture.  This  Debenture is in the  principal  amount of
$2,500,000  and is being  issued by the  Company to the Holder  pursuant  to the
payment of Two Million Five Hundred Thousand Dollars ($2,500,000) cash by Holder
to the Company.  In  connection  therewith,  the Company shall pay to Holder all
principal  and accrued  interest on that certain  Advance Note in the  principal
amount of $300,000, payable by Company to Holder dated November 1, 1999, and the
security  interest in certain vehicles and additions  thereto and  substitutions
therefor  created by that  certain  Security  Agreement  between  the Company as
debtor  and the  Holder as  secured  party  dated  November  1,  1999,  shall be
terminated  and the  collateral  with respect  thereto shall be released and all
title  documents  with  respect to such  vehicles  held by the  Holder  shall be
returned to the Company. The Holder hereby agrees to receive such Debenture from
the Company  pursuant  to the terms of this  Agreement,  and the Company  hereby
agrees to issue, convey,  transfer, and assign to the Holder, the Debenture free
and  clear  of all  liens,  options,  claims,  and  encumbrances  of any kind or
character  whatsoever,  except for applicable transfer  restrictions required by
federal and state  securities  laws.  The Debenture  may have such  notations or
legends as are required by applicable  law. The  Debenture  shall be executed on
behalf of the Company by its president or any vice  president and attested to by
its secretary of any assistant  secretary.  The Debenture  shall recite upon its
face the principal amount of indebtedness  evidenced by the Debenture,  the rate
at which interest is payable on the Debenture, and the terms of repayment.

     Section 2.02.  Acquisition  Price.  If the Debenture is being received from
the Company upon issuance,  the acquisition price for the Debenture shall be the
aggregate  principal amount thereof.  No original issue discount is contemplated
by the issuance of these Debentures.

     Section 2.03.  [Intentionally Omitted]

     Section  2.04.  Registration.  The  Debentures  shall be  registered in the
Debenture  records of the  Company as  follows:  The  Company  shall  maintain a
register of the issuance of the  Debentures by recording the issuance  date, the
face amount,  and the name and address of the initial  holder and, upon transfer
in accordance with Article X of this  Agreement,  each transferee of each of the
Debentures  upon the books of the  Company.  The  Company  shall be  entitled to
recognize  the person  registered  in the register as the  exclusive  owner of a
Debenture for the purposes of payment of principal and interest thereon, and the
Company  shall not be bound to  recognize  any  equitable  or other  claim to or
interest in such  Debenture on the part of any other person,  whether or not the
Company has express notice thereof,  except as otherwise  provided by applicable
law.

     Section  2.05.  Interest  on  Debenture.  Interest  shall be payable on the
outstanding  principal amount of the Debenture at the Interest Rate. Interest on
the  Debenture  shall be  calculated  on the basis of a  360-day  year of twelve
30-day months.  Interest shall be calculated  semi-annually as of December 1 and
June 1 of each year from the  Issuance  Date through the last such date prior to
the Maturity Date and on the Maturity Date, and accrued interest as of each such
date  shall be due and  payable  fifteen  calendar  days  after  each such date,
provided that the first such date on which interest shall be calculated and paid
shall be the first such semi-annual date following the original  issuance of the
Debenture.  If the  Company  fails  to pay to the  Holder  any  portion  of cash
interest that has accrued on the principal  amount of the Debenture when payment
is due, such unpaid  portion of accrued  interest  shall continue to be due from
and payable by the Company to the Holder until paid.  Interest  shall be payable
in cash, provided that for each interest payment due and payable through January
1, 2001, the interest payment shall be by payment in kind securities by issuance
of additional Debentures of like tenor as this Debenture with a principal amount
equal to the  amount of the cash  interest  payment  which  would have been paid
("PIK  Interest").  For each  interest  payment due and payable after January 1,
2001,  payment  shall be by cash or by PIK Interest at the election of Holder by
written  notice to the  Company,  provided  that the Company  shall only pay PIK
Interest  and not cash  interest  in the event  the  Company's  earnings  before
deduction of interest, taxes, depreciation and amortization (EBITDA) for the six
(6) months ended with the previous quarter (for the December 1 payment:  the six
(6) months ended  September  30; and for the June 1 payment:  the six (6) months
ended  March 31) are less than one  hundred  twenty-five  percent  (125%) of the
Company's  obligation for such interest  payment and for all other dividends and
interest due and payable on all other  outstanding  securities of the Company as
of such time. The Company hereby agrees that interest  payments on the Debenture
shall  take  priority  over any  preferred  stock  dividends  payable to current
holders of the Company's 8% Series C Convertible Exchangeable Preferred Stock.

     Section 2.06.  Lost or Stolen  Certificates.  In the event the  certificate
representing the Debenture is destroyed,  misplaced, or stolen, the Holder shall
promptly notify the Company of such loss. In its discretion, the Company may, as
a condition  precedent to  reissuing a new  Debenture  certificate,  require the
Holder to do one or more of the following things:

     (a) Deliver a notice to the Company in the form  prescribed  by the Company
requesting the Company to stop transfer of such lost Debenture certificate;

     (b) Execute and deliver to the Company an affidavit  of the facts  covering
the loss of the Debenture certificate; and

     (c) Execute and file any form  required by any state or federal  regulatory
authority in connection with the loss of the Debenture certificate.

After the  Holder has  complied  with such  requirements  as the  Company  deems
necessary and appropriate,  the Company shall cancel the lost certificate in its
register and shall issue a new  Debenture  certificate  to the Holder with terms
and provisions identical to those contained in the lost certificate.

     Section  2.07.  Governmental  Charges.  For any  transfer of a Debenture or
exchange of a Debenture for Debentures of another denomination,  the Company may
require from the Holder the payment of a sum  sufficient to reimburse it for any
stamp tax or other governmental charge incidental thereto.




                                ARTICLE III

                         PREPAYMENT OF DEBENTURES

     Section 3.01.  Optional  Prepayment of Debentures.  The Company may, at any
time after  December  1, 2001,  prepay  the  Debentures  in whole or in part (in
amounts  of not less than  $50,000)  by  payment of one  hundred  fifty-two  and
174/1000  percent  (152.174%)  of  the  outstanding   principal  amount  of  the
Debentures,  or  portion  thereof to be  prepaid,  and  payment  of the  accrued
interest thereon to the date of prepayment.  Except as set forth in this Article
III, the Company may not prepay the Debentures prior to maturity.

     Section 3.02. Notice of Prepayments.  The Company shall give written notice
of any  prepayment  of the  Debentures  pursuant to Section 3.01, to each holder
thereof  not less than thirty (30) days nor more than sixty (60) days before the
date fixed for such  optional  prepayment.  Such notice  shall  specify (i) such
date, and (ii) the principal amount of the holder's Debentures to be prepaid and
the  aggregate  principal  amount of all  Debentures  to be  prepaid.  Notice of
prepayment  having been so given,  one hundred  fifty-two  and 174/1000  percent
(152.174%) of the aggregate principal amount of the Debentures specified in such
notice,  and the accrued  interest  thereon  shall become due and payable on the
prepayment date.

     Section 3.03.  Allocation of  Prepayments.  All partial  prepayments of the
Debentures  shall be applied on all  outstanding  Debentures  then being prepaid
ratably in accordance with the unpaid principal amounts of the Debentures.

     Section  3.04.  Merger or Sale. In the event of the  consolidation  with or
merger of the Company  with or into  another  corporation  or entity,  or in the
event of the sale,  lease or conveyance to another  corporation or entity of the
assets of the Company as an entirety or substantially as an entirety, then, upon
the written  request of any Holder of the  Debentures,  the Company shall prepay
such Holder's  Debentures in whole by payment of one hundred  percent  (100%) of
the  principal  amount of the  Debentures  and payment of the  accrued  interest
thereon to the date of  prepayment,  within  thirty  (30) days of the  Company's
receipt of such written request.





<PAGE>


                               ARTICLE IV

                FINANCIAL STATEMENTS AND OTHER INFORMATION.

     Section 4.01.  Financial and Business  Information.  The Company  agrees to
furnish to you so long as you or your  nominee  are the holder of any  Debenture
and to each other holder of the then outstanding Debentures:

     (a) Quarterly  Statements.  Within 45 days after the end of each  quarterly
fiscal  period  (except the last) in each fiscal year of the Company,  duplicate
copies of:

     (1)  consolidated  balance  sheets of the  Company  as of the close of such
period,

     (2) consolidated  statements of income and retained earnings and changes in
financial  position of the Company for such quarterly  fiscal period and for the
portion of the fiscal year ending with such period, and

          (3)  consolidated  statements  of cash  flows of the  Company  for the
portion of the fiscal year ending with such period.

in each case (except (a)(1) above) setting forth in comparative form the figures
for the  corresponding  period of the preceding  fiscal year,  all in reasonable
detail and  certified  as having been  prepared  in  accordance  with  generally
accepted accounting  principles,  but subject to changes resulting from year-end
adjustments, by an authorized financial officer of the Company.

     (b) Annual Statements. As soon as available and in any event within 90 days
after the close of each fiscal year of the Company, duplicate copies of:

          (1) audited consolidated balance sheets of the Company as of the close
of such fiscal year, and

     (2) audited  consolidated  statements  of income and retained  earnings and
changes in financial position of the Company for such fiscal year.

In each case setting  forth in  comparative  form the figures for the  preceding
fiscal year, all in reasonable  detail and  accompanied,  in the case of audited
statements, by an opinion thereon of a firm of independent public accountants of
recognized  national  standing  selected  by the  Company to the effect that the
audited  financial  statements  have been prepared in accordance  with generally
accepted accounting principals consistently applied (except for changes in which
such  accountants  concur) and that the audit by such  accountants in connection
with financial  statements has been made in accordance  with generally  accepted
auditing standards.

     The financial statements delivered pursuant to paragraphs (a) and (b) above
shall  set  forth  the  amounts  charged  in each of the  periods  involved  for
depreciation and amortization, and for interest expense.

     (c) Audit Reports.  Promptly upon receipt thereof, one copy of each interim
or special audit made by independent accountants of the books of the Company.

     (d) SEC and Other Reports. Promptly upon their becoming available, one copy
of each  financial  statement,  report,  notice or proxy  statement  sent by the
Company to stockholders  generally, of each Form 8-K, 10-KSB, and 10-QSB, or any
successor  forms,  and any  registration  statement or  prospectus  filed by the
Company with any securities exchange or with the Securities Exchange Commission,
and of all press releases and other  statements made available  generally by the
Company to the public  concerning  material  developments in the business of the
Company.

     (e) Together with each set of quarterly  statements  and annual  statements
pursuant to paragraphs (a) and (b) above, a certificate of an executive  officer
of the Company that such financial  statements are true and correct and that the
Company is not then in default under the terms of this Debenture.

                               ARTICLE V

              REPRESENTATIONS AND WARRANTIES OF THE COMPANY

     The Company hereby represents and warrants to Holder as follows:

     Section 5.01.  Corporate  Organization.  The Company is a corporation  duly
organized and validly  existing and in good standing under the laws of the State
of Texas and has all  requisite  corporate  power and  authority to carry on its
business as now  conducted  and  proposed to be  conducted;  the Company has all
requisite  corporate power and authority to enter into this Agreement,  to issue
the Debenture and the shares  issuable upon the conversion  thereof and to carry
out the provisions  and  conditions of this Agreement and of the Debenture.  The
Company is duly  qualified and authorized to do business and is in good standing
as a foreign  corporation  in all states where the  ownership of property or the
nature of the  business  transacted  by the  Company  makes  such  qualification
necessary.  The Company has 25,000,000 authorized shares of its Common Stock and
4,000,000  authorized shares of its preferred stock. As of December 1, 1999, the
Company had 2,253,184 issued and outstanding  shares of Common Stock,  1,115,750
issued and outstanding  shares of preferred stock and 31,944 treasury shares. As
of December 1, 1999,  the Company had granted stock options  which,  if all were
exercised,  would equal 179,831 shares of Common Stock.  As of December 1, 1999,
the Company had issued one or more warrants which, if all are exercised, will in
the  aggregate  equal  1,136,574  shares of Common  Stock.  Additionally,  as of
December 1, 1999,  excluding  the shares of Common Stock to be received by WEDGE
upon its  election to convert to Common  Stock,  there are  2,789,375  shares of
Common Stock to be issued if all existing  preferred stock holders were to elect
to convert their shares to Common Stock.

     Section 5.02.  Corporate  Power.  The Company has all  requisite  power and
authority to enter into this Agreement,  to issue,  sell,  convey,  assign,  and
transfer the Debenture to the Holder, to own, operate,  and lease its properties
and other  assets and to carry on its  business  as now being  conducted  in the
place or places  where such  properties  or other assets are now owned or leased
and  such  business  is  now   conducted.   No  provision  of  the  Articles  of
Incorporation  or Bylaws of the Company would  preclude any of the  transactions
contemplated by this Agreement.

     Section 5.03. Corporate Authorization.  The execution of this Agreement and
the  consummation  of the  transactions  contemplated  hereunder  have been duly
approved  by all  necessary  corporate  action  of the  Company.

     Section  5.04.Debenture.  The Debenture  deliverable  by the Company to the
Holder  hereunder  will be duly  authorized  and  issued,  free and clear of all
liens,  options,  claims, and encumbrances of any kind or character  whatsoever,
except for  applicable  transfer  restrictions  required  by  federal  and state
securities laws.

     Section 5.05. Compliance with Material Agreements.  The Company is not, and
upon the issuance of the  Debenture to the Holder,  will not be in default under
any material  contract or agreement to which it is a party,  which default might
reasonably  be  anticipated  to result  in any  material  adverse  change in the
business,  properties or condition  (financial or otherwise) of the Company.  So
long as no Event of Default  (as defined  herein)  shall have  occurred,  and be
continuing  with respect to the  Debenture,  the Company may pay dividends  with
respect to its equity securities in accordance with the terms and rights of such
securities.

                               ARTICLE VI

               REPRESENTATIONS AND WARRANTIES OF HOLDER

     The Holder hereby represents and warrants to Company:

     Section 6.01.  Power and Authority.  The Holder has all requisite power and
authority  to enter  into  this  Agreement  and to  acquire  the  Debenture.  No
provision  of  the  Articles  of  Incorporation,   Bylaws,  or  other  governing
instruments of the Holder would preclude any of the transactions contemplated by
this Agreement.

     Section  6.02.  Authorization.  The  execution  of this  Agreement  and the
consummation of the transactions  contemplated herein have been duly approved by
all necessary action, corporate and otherwise, of the Holder.

     Section  6.03.  Investment  Intent.  The Holder is acquiring  the Debenture
solely for its own account  and not with a view to, or for resale in  connection
with, any  distribution  or public offering  thereof,  within the meaning of any
applicable securities laws and regulations.

                              ARTICLE VII

                             SUBORDINATION

     Section 7.01. Debentures Subordinated to Superior Indebtedness.
Anything in this  Agreement or the  Debentures to the contrary  notwithstanding,
the  indebtedness   evidenced  by  the  Debentures  (such   indebtedness   being
hereinafter  referred to as Subordinated  Indebtedness) shall be subordinate and
junior in right of  payment,  to the extent and in the  manner  hereinafter  set
forth,  to (but only to) all Superior  Indebtedness  (as defined  herein) of the
Company.

     Section 7.02.  Payments on Subordinated Indebtedness.

     (a) So long as no default or event of default  shall have  occurred  and be
continuing  with respect to any Superior  Indebtedness  under the terms thereof,
the Company will pay the principal and interest on all Subordinated Indebtedness
according to the terms thereof.

     (b) During the  continuance  of any default  with  respect to any  Superior
Indebtedness under the terms thereof, including, without limitation, any default
in the payment of either principal or interest on any Superior Indebtedness,  no
payment of  principal,  premium or  interest  shall be made on the  Subordinated
Indebtedness,  if either (i) notice of such  default in writing or by  facsimile
has been  given  to the  Company  by the  holder  or  holders  of such  Superior
Indebtedness;  or (ii) judicial  proceedings shall be pending in respect of such
default.

     Section  7.03.  Insolvency,  etc.  In  the  event  of (a)  any  insolvency,
bankruptcy,    receivership,    liquidation,    reorganization,    readjustment,
composition,  or  other  similar  proceeding  relating  to  the  Company  or its
property,  (b)  any  proceeding  for  the  liquidation,  dissolution,  or  other
winding-up  of  the  Company,  voluntary  or  involuntary,  and  whether  or not
involving  insolvency  or  bankruptcy  proceedings,  (c) any  assignment  by the
Company  for  the  benefit  of  creditors,  or (d) any  distribution,  division,
marshaling,  or application of any of the properties or assets of the Company or
the proceeds thereof to creditors,  voluntary or involuntary, and whether or not
involving legal proceedings, then and in such event:

     (i) all Superior  Indebtedness  shall first be paid in full  (including all
principal,  premium, if any, and interest, including interest accruing after the
commencement of any such  proceeding)  before any payment or distribution of any
character, whether in cash, securities, or other property (other than securities
of the Company or any other corporation provided for by a plan of reorganization
or readjustment or similar plan, the payment of which is subordinated,  at least
to the  extent  provided  in this  Article  VII  with  respect  to  Subordinated
Indebtedness,   to  the  payment  of  all  Superior  Indebtedness  at  the  time
outstanding and to any securities issued in respect thereof under any such plan)
is made in respect of any Subordinated Indebtedness;

     (ii) all  principal and premium,  if any, and interest on the  Subordinated
Indebtedness  shall  forthwith  become  due  and  payable,  and any  payment  or
distribution of any character,  whether in cash,  securities,  or other property
(other than securities of the Company or any other corporation provided for by a
plan of  reorganization or readjustment or similar plan, the payment of which is
subordinated,  at least to the extent  provided in this Article VII with respect
to Subordinated Indebtedness, to the payment of all Superior Indebtedness at the
time outstanding and to any securities  issued in respect thereof under any such
plan) which would otherwise (but for the terms hereof) be payable or deliverable
in respect of any Subordinated Indebtedness, shall be paid or delivered directly
to the holders of the Superior  Indebtedness,  until all  Superior  Indebtedness
shall have been paid in full, the holders of the  Subordinated  Indebtedness  at
the time outstanding  irrevocably authorize,  empower, and direct all receivers,
trustees, liquidators,  conservators, fiscal agents, and others having authority
in the premises to effect all such payments and deliveries;

               (iii) each holder of the  Subordinated  Indebtedness  at the time
outstanding  irrevocably  authorizes  and  empowers  each holder of the Superior
Indebtedness or such holder's  representative to demand,  sue for, collect,  and
receive such holder's ratable share of all such payments and  distributions  and
to receipt therefor, and to file and prove all claims therefor and take all such
other  action,  in the name of such holder or  otherwise,  as such holder of the
Superior  Indebtedness  or such  holder's  representative  may  determine  to be
necessary or appropriate for the enforcement of this Section 7.03; and

               (iv) the holders of the Subordinated  Indebtedness  shall execute
and  deliver  to each  holder  of the  Superior  Indebtedness  or such  holder's
representative all such further instruments  confirming the above authorization,
and all such powers of  attorney,  proofs of claim,  assignments  of claim,  and
other  instruments,  and shall take all such other action as may be requested by
such holder of the Superior  Indebtedness  or such  holder's  representative  to
enforce all claims upon or in respect of the Subordinated Indebtedness.

For all purposes of this Agreement, Superior Indebtedness shall not be deemed to
have been paid in full unless the holders thereof shall have received cash equal
to the amount of  principal,  premium,  if any,  and  interest in respect of all
Superior Indebtedness at the time outstanding, and in case there are two or more
holders of the Superior  Indebtedness any payment or distribution required to be
paid or delivered to the holders of the Superior  Indebtedness  shall be paid or
delivered to such holders ratably according to the respective  aggregate amounts
remaining unpaid on the Superior Indebtedness of such holders.

     Section  7.04.  Payments  and  Distributions  Received.  If any  payment or
distribution of any character (whether in cash,  securities,  or other property)
or any  security  shall be  received  by any  holder of any of the  Subordinated
Indebtedness  in  contravention  of any of the terms of this  Article  VII,  and
except  as  permitted  by  Section  7.03  or  Section  7.06,   such  payment  or
distribution or security shall be held in trust for the benefit of, and shall be
paid  over  or  delivered  and  transferred  to,  the  holders  of the  Superior
Indebtedness  for  application  to  the  payment  of all  Superior  Indebtedness
remaining unpaid, to the extent necessary to pay all such Superior  Indebtedness
in full.  In the event of the  failure of any holder of any of the  Subordinated
Indebtedness  to endorse or assign any such payment,  distribution  or security,
any holder of the  Superior  Indebtedness  or such  holder's  representative  is
hereby irrevocably authorized to endorse or assign the same.

     Section 7.05.  Subrogation.  In the event that cash,  securities,  or other
property  otherwise  payable and deliverable to the holders of the  Subordinated
Indebtedness shall have been applied pursuant to Section 7.03 or Section 7.04 to
the payment of Superior  Indebtedness  in full,  then and in each such case, the
holders of the  Subordinated  Indebtedness  shall be subrogated to any rights of
any  holders  of  Superior   Indebtedness   to  receive   further   payments  or
distributions in respect of or applicable to the Superior Indebtedness.

     Section  7.06.  Acceleration  of  Subordinated  Indebtedness.  In case  any
Subordinated  Indebtedness is declared due and payable because of the occurrence
of an Event of Default  with  respect  to the  Subordinated  Indebtedness  under
circumstances when the terms of Section 7.03 are not applicable,  the holders of
such  Subordinated  Indebtedness  shall not be  entitled  to receive  payment or
distribution  in respect  thereof  until all Superior  Indebtedness  at the time
outstanding shall have been paid in full;  provided,  however,  that, so long as
such Event of Default  does not  constitute  a default or event of default  with
respect  to  any  Superior   Indebtedness,   the  holders  of  the  Subordinated
Indebtedness  shall  continue to be  entitled  to receive  (i) current  interest
payments,  (ii) regularly  scheduled  prepayments  pursuant to Section 3.01, and
(iii) payments due at the stated maturity, notwithstanding such declaration.

     Section 7.07. Notice. In the event that any Subordinated Indebtedness shall
become due and  payable  before its  expressed  maturity on demand of the holder
thereof as the result of the  occurrence  of a default or event of default,  the
Company will give prompt  notice in writing of such  happening to each holder of
Superior Indebtedness.

     Section 7.08.  Subordination  Not Affected,  etc. The terms of this Article
VII, the  subordination  effected  hereby,  and the rights of the holders of the
Superior  Indebtedness shall not be affected by (a) any amendment of or addition
or  supplement  to any  Superior  Indebtedness  or any  instrument  or agreement
relating  thereto,  (b) any exercise or  non-exercise  of any right,  power,  or
remedy under or in respect of any Superior  Indebtedness  or any  instrument  or
agreement relating thereto,  or (c) any waiver,  consent,  release,  indulgence,
extension, renewal, modification,  delay, or other action, inaction or omission,
in respect of any Superior  Indebtedness or any instrument or agreement relating
thereto or any security therefor or guaranty thereof,  whether or not any holder
of any  Subordinated  Indebtedness  shall have had notice or knowledge of any of
the foregoing.  In addition,  in the event that any holder or prospective holder
of Superior Indebtedness  reasonably requires a modification or amendment of the
terms of this Article VII with respect to the  subordination of the Subordinated
Indebtedness, the Holder agrees to execute any such modification or amendment to
this Article VII with respect thereto.

     Section  7.09.  Obligations  Unimpaired.  No  present  or future  holder of
Superior  Indebtedness shall be prejudiced in the right to enforce subordination
of the Subordinated Indebtedness by any act or failure to act on the part of the
Company.  The  provisions  of this  Article  VII are solely  for the  purpose of
defining the relative rights of the holders of Superior  Indebtedness on the one
hand and the holders of Subordinated Indebtedness on the other hand, and nothing
in this  Article  VII shall (a) impair as between  the Company and the holder of
any  Subordinated   Indebtedness  the  obligation  of  the  Company,   which  is
unconditional and absolute, to pay to the holder thereof the principal, premium,
if any,  and  interest  thereon in  accordance  with the terms  thereof,  or (b)
prevent the holder of any Subordinated Indebtedness from exercising all remedies
otherwise  permitted  by  applicable  law under this  Agreement,  subject to the
rights, if any, under this Article VII of the holders of Superior Indebtedness.

     Section 7.10. Securities Subordinate to Debenture. All equity securities of
the Company shall be subordinate and junior in right of payment as to dividends,
and on  liquidation,  to the rights of the Debenture to payment of principal and
interest and on liquidation.

                            ARTICLE VIII

                      CONVERSION OF DEBENTURES

     Section 8.01.  Conversion  Privilege.  The unpaid  principal  amount of any
Debenture or any portion thereof may, at the election of the holder thereof,  at
any time after the date of such Debenture be converted into (a) shares of Common
Stock at the  conversion  price  per  share of Common  Stock of One  Dollar  and
Fifteen Cents ($1.15) or (b) shares of Senior  Convertible  Preferred  Stock, at
the conversion price per share of such Senior Convertible Preferred Stock of One
Dollar and Fifteen Cents ($1.15),  provided that if the holders of the Company's
8% Series C  Convertible  Exchangeable  Preferred  Stock  ("Series  C  Preferred
Stock") do not  provide  the  necessary  waivers  under the terms  thereof  with
respect to the  issuance of the Senior  Convertible  Preferred  Stock,  then the
Debenture  at the  Holders'  option  may be  converted  into  shares of Series D
Convertible  Preferred  Stock with terms which are pari passu with the Company's
Series C Preferred  Stock, or any  outstanding  series of preferred stock of the
Company with rights and terms  superior  thereto,  at the  conversion  price per
share of Series D  Convertible  Preferred  Stock of One Dollar and Fifteen Cents
($1.15),  further provided that, in any event, such Senior Convertible Preferred
Stock or Series D  Convertible  Preferred  Stock  issued  to the  Holder on such
conversion shall itself have conversion rights into shares of Common Stock which
provide that each share of preferred stock shall be initially  convertible  into
one (1) share of Common  Stock,  as such  conversion  price may be adjusted  and
readjusted  from time to time in  accordance  with  Section  8.05  hereof  (such
conversion price, as so adjusted and readjusted and in effect at any time, being
herein  called  the  "Conversion  Price"),  into the  number  of fully  paid and
non-assessable  shares of Common Stock  determined by dividing (x) the aggregate
principal  amount of the  Debentures  to be so converted  by (y) the  Conversion
Price in effect at the time of such conversion.

     Section 8.02.  Manner of Conversion; Partial Conversion, etc.

     (a) Any  Debenture  may be  converted  in  whole  or in part by the  holder
thereof by  surrender  of such  Debenture,  accompanied  by a written  statement
designating  the principal  amount of such Debenture to be converted and stating
the name and  address  of the person in whose  name  certificates  for shares of
Common Stock are to be registered,  at the office of the Company specified in or
pursuant to Section 15.01. Upon any such partial conversion of a Debenture,  the
Company at its expense will forthwith  issue and deliver to or upon the order of
the holder  thereof a new Debenture or  Debentures in principal  amount equal to
the unpaid and unconverted principal amount of such surrendered Debenture,  such
new  Debenture or  Debentures  to be dated and to bear interest from the date to
which  interest has been paid on such  surrendered  Debenture.  Each  conversion
shall be deemed to have been effected as of the close of business on the date on
which such Debenture shall have been so surrendered to such office,  and at such
time the rights of the holder of such Debenture as such shall,  to the extent of
the principal  amount  thereof  converted,  cease,  and the person or persons in
whose name or names any certificate or  certificates  for shares of Common Stock
shall be issuable upon such conversion shall be deemed to have become the holder
or holders of record thereof.

     (b) The Company  shall pay all cash interest on any Debenture or portion of
any Debenture surrendered for conversion to the date of such conversion.

     Section 8.03.  Delivery of Stock  Certificates.  As promptly as practicable
after  the  conversion  of any  Debenture  in full or in part,  and in any event
within 20 days thereafter,  the Company at its expense (including the payment by
it of any  applicable  issue taxes) will issue and deliver to the holder of such
Debenture,  or as such holder  (upon  payment by such  holder of any  applicable
transfer taxes) may direct, a certificate or certificates for the number of full
and fractional shares of Common Stock issuable upon such conversion.

     Section 8.04.  Shares to be Fully Paid; Reservation of Shares.

The Company  covenants  and agrees that all shares of Common  Stock which may be
issued upon conversion of the Debentures will, upon issuance,  be fully paid and
non-assessable  and free from all taxes,  liens, and charges with respect to the
issue thereof; and without limiting the generality of the foregoing, the Company
covenants  and agrees that it will from time to time take all such action as may
be requisite to assure that the par value (if any) per share of the Common Stock
is at all times  equal to or less  than the then  effective  purchase  price per
share of the Common  Stock  issuable  upon  conversion  of the  Debentures.  The
Company  further  covenants  and agrees that the Company  will at all times have
authorized,  and  reserved  for the  purpose  of  issue  or  transfer  upon  the
conversion of the Debentures,  a sufficient number of shares of its Common Stock
to provide for the conversion of the Debentures.

     Section 8.05.  Conversion Price Adjustments.  The Conversion Price shall be
subject to adjustment from time to time as follows:

     (a) Stock Dividends,  Subdivisions,  Reclassifications or Combinations.  If
the  Corporation  shall (i)  declare a dividend  or make a  distribution  on its
Common Stock in shares of its Common Stock,  (ii)  subdivide or  reclassify  the
outstanding  shares of Common  Stock into a greater  number of shares,  or (iii)
combine or  reclassify  the  outstanding  Common Stock into a smaller  number of
shares,  the Conversion  Price in effect at the time of the record date for such
dividend or distribution or the effective date of such subdivision,  combination
or reclassification shall be proportionately  adjusted so that the holder of any
Debentures  surrendered  for  conversion  after such date shall be  entitled  to
receive  the number of shares of Common  Stock which he would have owned or been
entitled to receive had such Debentures been converted immediately prior to such
date. Successive  adjustments in the Conversion Ratio shall be made whenever any
event specified above shall occur.

          (b) Other  Distributions.  In case the Corporation  shall fix a record
date for the  making of a  distribution  to all  holders of shares of its Common
Stock  (i) of  shares  of any  class  other  than  its  Common  Stock or (ii) of
evidences of  indebtedness  of the  Corporation  or any  Subsidiary  or (iii) of
assets   (excluding   cash   dividends  or   distributions,   and  dividends  or
distributions  referred to in subparagraph  8.05(a) above), or (iv) of rights or
warrants,  in each such case of (i) through (iv) the Conversion  Price in effect
immediately  prior  thereto  shall  be  immediately  thereafter  proportionately
adjusted  for  such  distribution  so that the  holder  of  Debentures  would be
entitled  to  receive  the fair  market  value  (as  determined  by the Board of
Directors,  whose  determination  in good faith shall be  conclusive)  of what a
Holder would have been entitled to receive had such  Debentures  been  converted
prior to such distribution.  Such adjustment shall be made successively whenever
such a record date is fixed. In the event that such distribution is not so made,
the  Conversion  Price then in effect shall be  readjusted,  effective as of the
date when the Board of  Directors  determines  not to  distribute  such  shares,
evidences of indebtedness,  assets,  rights or warrants,  as the case may be, to
the  Conversion  Price which would then be in effect if such record date had not
been fixed.

          (c) Consolidation,  Merger, Sale, Lease or Conveyance.  In case of any
consolidation   with  or  merger  of  the  Corporation   with  or  into  another
corporation,  or in case of any sale, lease or conveyance to another corporation
of the assets of the Corporation as an entirety or substantially as an entirety,
the Debentures shall after the date of such consolidation,  merger,  sale, lease
or  conveyance  be  convertible  into the  number  of  shares  of stock or other
securities  or  property  (including  cash) to which the shares of Common  Stock
issuable (at the time of such consolidation,  merger, sale, lease or conveyance)
upon  conversion  of such  Debenture  would  have  been  entitled  to upon  such
consolidation,  merger,  sale,  lease or  conveyance;  and in any such case,  if
necessary,  the  provisions  set forth  herein  with  respect  to the rights and
interests  thereafter of the holders of the  Debentures  shall be  appropriately
adjusted so as to be  applicable,  as nearly as may reasonably be, to any shares
of  stock  or  other  securities  or  property  thereafter  deliverable  on  the
conversion of the Debentures.

     Section 8.06.  Statement  Regarding  Adjustments.  Whenever the  Conversion
Price  shall be adjusted as provided  in Section  8.05,  the  Corporation  shall
forthwith file, at the principal office of the Corporation,  a statement showing
in detail the facts  requiring such  adjustment  and the  Conversion  Price that
shall be in effect after such adjustment, and the Corporation shall also cause a
copy of such statement to be sent by mail, first class postage prepaid,  to each
holder of Debentures,  at its address  appearing on the  Corporation's  records.
Where appropriate, such copy may be given in advance and may be included as part
of a notice required to be mailed under the provisions of Section 8.07.

     Section 8.07. Notice to Holders. In the event the Corporation shall propose
to take any action of the type described in Section 8.05, the Corporation  shall
give  written  notice to each holder of  Debentures,  in the manner set forth in
Section  8.06,  which notice shall specify the record date, if any, with respect
to any such  action and the  approximate  date on which  such  action is to take
place. Such notice shall also set forth such facts with respect thereto as shall
be  reasonably  necessary  to indicate  the effect of such action (to the extent
such effect may be known at the date of such notice) on the Conversion Price and
the number,  kind or class of shares which shall be deliverable  upon conversion
of  Debentures.  In the case of any action  which would  require the fixing of a
record date,  such  written  notice shall be given at least 15 days prior to the
taking of such  action.  Failure  to give such  written  notice,  or any  defect
therein, shall not affect the legality or validity of any such action.

     Section 8.08.  Costs.  The Corporation  shall pay all  documentary,  stamp,
transfer or other  transactional  taxes attributable to the issuance or delivery
of shares of Common Stock upon conversion of any  Debentures;  provided that the
Corporation  shall not be  required  to pay any taxes  which may be  payable  in
respect of any transfer  involved in the issuance or delivery of any certificate
for such  shares in a name other than that of the holder of the  Debentures,  in
respect of which shares are being issued.

                                 ARTICLE IX

                            DEFAULT AND REMEDIES

     Section  9.01.  Event  of  Default.  As  used  in  this  Agreement  and the
accompanying  Debenture,  the  term"Event of Default"  shall mean any one of the
following:

     (a) a default in the payment of interest on any Debenture when due and such
     default shall  continue for more than fifteen (15) days from such due date;
     (b) a default in the payment of the  principal of Debentures at maturity or
     at any date fixed in any notice for prepayment;

     (c) the Company sells or otherwise  disposes of all or substantially all of
its assets to any Person;

     (d) a default in the observance or performance of any covenant or provision
of this  Agreement or of the  Purchase  Agreement  which is not remedied  within
thirty (30) days after  written  notice  thereof to the Company by the holder of
any Debenture;

     (e) any  representation  or warranty  made by the Company  herein or in the
Purchase  Agreement,  or  made  by the  Company  in  any  written  statement  or
certificate  furnished by the Company in connection with the consummation of the
issuance and  delivery of the  Debentures  or furnished by the Company  pursuant
hereto,  is untrue in any  material  respect as of the date of the  issuance  or
making thereof;

     (f) final  judgment or Judgments  for the payment of money  aggregating  in
excess of $250,000 is or are  outstanding  against the Company or any Subsidiary
or against any of the  property or assets of the Company or any  Subsidiary  and
any one of such judgments has remained unpaid,  unvacated,  unbonded or unstayed
by appeal  or  otherwise  for a period of thirty  (30) days from the date of its
entry;

     (g) the  Company  or any  Subsidiary  becomes  insolvent  or  bankrupt,  is
generally not paying its debts as they become due or makes an assignment for the
benefit of  creditors,  or the  Company or any  Subsidiary  causes or suffers an
order for  relief to be entered  with  respect  to it under  applicable  Federal
bankruptcy  law or applies for or consents to the  appointment  of a  custodian,
trustee or receiver for the Company or any  Subsidiary  or for the major part of
the property of the Company or any Subsidiary;

     (h) a custodian,  trustee or receiver is  appointed  for the Company or any
Subsidiary  or for  the  major  part  of the  property  of  the  Company  or any
Subsidiary and is not discharged  within sixty (60) days after such appointment;
or

     (i) bankruptcy,  reorganization,  arrangement or insolvency proceedings, or
other proceedings for relief under any bankruptcy or similar law or laws for the
relief of debtors,  are  instituted by or against the Company or any  Subsidiary
and, if instituted  against the Company or any  Subsidiary,  are consented to or
are not dismissed within sixty (60) days after such institution.

     Section 9.02.  Default Remedies.

     (a) Upon the  occurrence  of an Event of Default,  the Holder may, upon ten
(10) days prior written notice to the Company,  declare the Debenture to be, and
the outstanding principal amount of the Debenture shall thereupon be and become,
forthwith due and payable in cash, together with interest accrued thereon; and

     (b) If an Event of Default  occurs,  the Holder may  proceed to protect and
enforce  its rights by a suit in  equity,  action at law,  or other  appropriate
proceeding,  whether for the specific  performance  of any  agreement  contained
herein  or for an  injunction  against  a  violation  of  any  of the  terms  or
provisions  hereof,  or in aid of the exercise of any power granted herein or by
law.

     Section 9.03. Waiver of Events of Default.  The holders of 51 percent (51%)
of the aggregate principal amount of the Debentures  outstanding may at any time
waive an existing Event of Default and its consequences.

                                   ARTICLE X

                            TRANSFER OF DEBENTURE

     Section  10.01.   Restriction  on  Transfer.   In  addition  to  any  other
restrictions on transfer of the Debenture  imposed by this Article X, the Holder
may  transfer  or assign  his,  her,  or its rights and  obligations  under this
Agreement only in conjunction with the transfer or assignment of the Debenture.

     Section 10.02. Requirements of Transfer. No transfer of the Debenture shall
be valid and effective  unless and until (a) the  transferor  executes a written
assignment of the Debenture or executes a separate power of attorney  indicating
his intent to  transfer  ownership,  (b) the  transferee  executes  a  Debenture
Agreement,  which shall be identical to this  Agreement  except for the Holder's
name and the date of execution, and (c) the transferor delivers written transfer
instructions  (i) signed by the transferor and the transferee,  (ii) stating the
name and mailing and residence address of the transferee,  and (iii) stating the
desired  effective date of such change of ownership.  If the transferee fails to
execute a Debenture Agreement, the transferee's signature on the instructions of
transfer will be deemed to constitute  the  transferee's  assent to the terms of
the Debenture and the Debenture Agreement.

     Section 10.03. Registration of Transfer. Transfer of the Debenture shall be
registered  upon the Company's  register of  Debentures  following the Company's
receipt of all documents necessary to effect transfer in accordance with Section
10.02.  Such documents may be either  personally  delivered by the transferor or
transferee or mailed to the Company in accordance with Section 15.01 hereof.

     Section  10.04.  Effective  Date of  Transfer.  The  effective  date of the
transfer  recorded on the  Company's  register of  Debentures  shall be the date
requested  in the  instructions  of  transfer;  the  effective  date  shall not,
however,  precede the date of the most  recent  payment  date of  interest  with
respect to such Debenture.  In the event such date precedes the date of the most
recent  payment of interest on the  Debenture  or if the desired date is omitted
from the  instructions of transfer,  the Company may in its discretion honor the
transfer,  and, in such case,  the effective date of transfer shall be the first
date at which the Company is in receipt of all of the items  required by Section
10.02 hereof.

     Section  10.05.  Transferee  as Holder.  Upon  completion  of a transfer in
accordance with the provisions provided in this Article X, such Transferee shall
be considered  the Holder as if the  transferee  had been the original  party to
execute this Agreement.

     Section 10.06. Issuance of New Certificates.  Upon a transfer in accordance
with this Article X, and upon  delivery by the  transferor  of his,  her, or its
Debenture certificate representing the Debenture being transferred,  the Company
shall cancel such Debenture certificate and shall issue a new certificate in the
transferee's  name.  Such new  certificate  shall be issued in  accordance  with
Article II hereof,  and its  provisions  will be  identical  to those of the old
Debenture  certificate except as to the Holder's name and the date of execution,
which date on the new  certificate  shall be the same as the effective  transfer
date in accordance with Section 10.04 hereof.

     Section 10.07. Legend on Debenture.  The Debenture shall bear the following
legend:

     "THIS DEBENTURE HAS NOT BEEN  REGISTERED  UNDER THE SECURITIES ACT OF 1933,
AS AMENDED  (THE"ACT") OR THE SECURITIES LAWS OF ANY STATE,  AND HAS BEEN ISSUED
PURSUANT TO EXEMPTIONS FROM SUCH  REGISTRATION AND  QUALIFICATION  REQUIREMENTS.
THIS DEBENTURE MAY NOT BE SOLD, TRANSFERRED,  OR ASSIGNED WITHOUT THE PERMISSION
OF THE ISSUER AND UNLESS THIS DEBENTURE  SHALL HAVE BEEN DULY  REGISTERED  UNDER
THE ACT AND REGISTERED OR QUALIFIED UNDER  APPLICABLE STATE SECURITIES LAWS, OR,
IN  THE  OPINION  OF  COUNSEL  SATISFACTORY  TO  THE  ISSUER,  REGISTRATION  AND
QUALIFICATION OF THE DEBENTURE SHALL NOT BE REQUIRED.  THIS DEBENTURE IS SUBJECT
TO AND ITS TRANSFER IS  RESTRICTED  BY THE TERMS AND  PROVISIONS OF THAT CERTAIN
DEBENTURE AGREEMENT, DATED DECEMBER 1, 1999, EXECUTED BY AND BETWEEN THE COMPANY
AND THE HOLDER OF THIS  DEBENTURE,  A COPY OF WHICH IS ON FILE IN THE OFFICES OF
THE COMPANY."

                                 ARTICLE XI

                             REGISTRATION RIGHTS

     Section 11.01.  Registration  on Request.  Upon the written  request of any
holder or holders of at least fifty-one percent (51%) in the aggregate principal
amount of the Debentures  and/or fifty-one percent (51%) of the shares of Common
Stock, Senior Convertible  Preferred Stock and/or Series D Convertible Preferred
Stock ("Shares") issued upon conversion of such Debentures,  which request shall
state the  intended  method of  disposition  by such holder or holders and shall
request that the Company effect the  registration of all or part of such Shares,
or the Shares issuable upon the conversion of such  Debentures,  or both,  under
the  Securities  Act of 1933, as amended  (the"Act"),  the Company will promptly
give written notice of such requested registration to all holders of outstanding
Debentures  and Shares,  and  thereupon  will use its best efforts to effect the
registration under the Act of:

     (a) the Shares which the Company has been so  requested  to  register,  for
disposition in accordance with the intended method of disposition stated in such
request, and

     (b) all other outstanding Shares, or Shares issuable upon the conversion of
Debentures,  the holders of which shall have made written  request  (stating the
intended  method of  disposition  of such  securities  by such  holders)  to the
Company for  registration  thereof  within thirty (30) days after the receipt of
such written notice from the Company,

all to the extent  requisite to permit the  disposition  (in accordance with the
intended  methods  thereof  as  aforesaid)  by  the  holders  of the  Shares  so
registered  and  to  maintain  such  registration  in  effect  for a  period  of
twenty-four  (24) months;  provided,  that the Company  shall not be required to
register or use its best efforts to effect any  registration of Shares under the
Act  pursuant to this  Section  11.01 more than once.  In the event  that,  as a
result of such registration,  another person with incidental registration rights
granted by the Company  requests  that the Company  include  securities  of such
person in such registration,  such request will not result in a reduction in the
number of securities of the holder or holders of the Debentures and/or Shares to
be included in such registration.

     The Company shall have no obligation to register or use its best efforts to
effect any  registration  of Shares  under the Act  pursuant to this  Article XI
which  would be in  conflict  with the  obligations  of any holder or holders of
Debentures and/or Shares under any confidentiality agreement between such holder
or holders and the Company  entered into in connection  with the offering of the
Debentures to such holder or holders.

     Section 11.02. Incidental Registration. If the Company at any time proposes
to register any of its  securities  under the Act  (otherwise  than  pursuant to
Section  11.01 and other than a  registration  on Form S-8, or the form, if any,
which  supplants  such Form),  it will each such time give written notice to all
holders of outstanding Debentures and Shares of its intention to do so and, upon
the written  request of any such  holder made within  thirty (30) days after the
receipt of any such notice (which  request shall specify the Shares  intended to
be  disposed  of by such  holder and state the  intended  method of  disposition
thereof),  the Company will use its best  efforts to cause all such  outstanding
Shares,  or Shares  issuable upon the conversion of  Debentures,  the holders of
which shall have so requested the registration  thereof,  to be registered under
the Act to the extent  requisite to permit the  disposition  (in accordance with
the intended methods thereof as aforesaid) of the Shares so registered; provided
that, if in the good faith judgment of the managing  underwriter or underwriters
of  a  then  proposed  public  offering  of  the  Company's   securities,   such
registration  of such Shares would  materially and adversely  affect such public
offering,  then in such event the number of Shares  and other  securities  to be
registered  by the Company,  including,  without  limitation,  securities  to be
registered  pursuant to any other registration rights which have been granted by
the  Company,  shall each be  proportionally  reduced to such number as shall be
acceptable to the managing underwriter, subject to Section 11.01.

     Section  11.03.  Registration  Procedures.  If and  whenever the Company is
required  to use its best  efforts  to effect or cause the  registration  of any
Shares  under the Act as provided  in this  Article  XI, the  Company  will,  as
expeditiously as possible:

     (a)  prepare  and  file  with  the  Securities   and  Exchange   Commission
(the"Commission")  a registration  statement with respect to such Shares and use
its best efforts to cause such registration statement to become effective;

     (b) prepare and file with the Commission such amendments and supplements to
such registration  statement and the prospectus used in connection  therewith as
may be necessary to keep such registration  statement  effective for such period
not exceeding a period of twenty-four  (24) months as may be necessary to comply
with the  provisions  of the Act with respect to the  disposition  of all Shares
covered by such registration statement during such period in accordance with the
intended  methods of disposition  by the seller or sellers  thereof set forth in
such registration statement;

     (c)  furnish to each  seller of such  Shares  such number of copies of such
registration  statement and of each such  amendment and  supplement  thereto (in
each case  including  all  exhibits),  such  number of copies of the  prospectus
included in such registration  statement (including each preliminary  prospectus
and, if any seller shall so request, a summary  prospectus),  in conformity with
the  requirements  of the Act,  and such  other  documents,  as such  seller may
reasonably request in order to facilitate the disposition of the Shares owned by
such seller;

     (d) use its best efforts to register or qualify such Shares covered by such
registration  statement  under  such other  securities  or blue sky laws of such
jurisdictions as each seller shall reasonably request,  and do any and all other
acts and things  which may be  reasonably  necessary or advisable to enable such
seller to consummate the disposition in such  jurisdictions  of the Shares owned
by such seller; and

     (e) notify  each  seller of any such  Shares  covered by such  registration
statement,  at any time when a  prospectus  relating  thereto is  required to be
delivered  under the Act within the period  mentioned in subdivision (b) of this
Section 11.03, of the happening of any event as a result of which the prospectus
included in such registration  statement,  as then in effect, includes an untrue
statement of a material  fact or omits to state any material fact required to be
stated therein or necessary to make the statements therein not misleading in the
light of the circumstances then existing,  and at the request of any such seller
prepare and furnish to such seller a reasonable number of copies of a supplement
to or an amendment of such prospectus as may be necessary so that, as thereafter
delivered to the purchasers of such Shares, such prospectus shall not include an
untrue statement of a material fact or omit to state a material fact required to
be stated therein or necessary to make the statements  therein not misleading in
the light of the circumstances then existing.

     Section  11.04.   Registration  Expenses.  All  expenses  incident  to  the
Company's performance of or compliance with this Article XI, including,  without
limitation,  all  registration  and filing fees,  fees and expenses of complying
with securities or blue sky laws,  printing  expenses and fees and disbursements
of counsel for the Company and of independent pubic  accountants,  but excluding
underwriting  commissions and discounts,  the fees of any counsel engaged by the
Holder,  and any  filing  fees  associated  with  shares of  Senior  Convertible
Preferred Stock or Series D Convertible  Preferred  Stock, but not Common Stock,
being  listed  with a  national  securities  exchange  or quoted  on the  NASDAQ
National Market System or Small Cap Market, shall be borne by the Company.

     Section 11.05. Indemnification.

     (a) In the event of any  registration  of any Shares under the Act pursuant
to this Article XI, the Company will, to the extent permitted by law,  indemnify
and hold  harmless  the  seller  of such  Shares  and each  underwriter  of such
securities  and  each  other  person,  if  any,  who  controls  such  seller  or
underwriter within the meaning of the Act, against any losses, claims,  damages,
or  liabilities,  joint or  several,  to which  such  seller or  underwriter  or
controlling  person may become subject,  under the Act or otherwise,  insofar as
such losses,  claims,  damages,  or liabilities (or actions in respect  thereof)
arise  out of or are based  upon (i) any  untrue  statement  or  alleged  untrue
statement of any material fact contained,  on the effective date thereof, in any
registration  statement under which such  securities  were registered  under the
Act, any preliminary  prospectus or final prospectus  contained therein,  or any
amendment or  supplement  thereto,  or (ii) any omission or alleged  omission to
state therein a material fact required to be stated therein or necessary to make
the  statements  therein not  misleading;  and the Company will  reimburse  such
seller and each such underwriter and each such controlling  person for any legal
or  any  other  expenses   reasonably   incurred  by  them  in  connection  with
investigating or defending any such loss, claim, damage,  liability,  or action,
provided  that the  Company  shall not be liable in any such case to the  extent
that any such loss,  claim,  damage, or liability arises out of or is based upon
an untrue  statement or alleged untrue statement or omission or alleged omission
made in such  registration  statement,  any such preliminary  prospectus,  final
prospectus,  amendment or supplement  in reliance  upon and in  conformity  with
written information furnished to the Company through an instrument duly executed
by such seller or underwriter specifically for use in the preparation thereof.

     (b) The Company may require,  as a condition to including any Shares in any
registration  statement filed pursuant to Section 11.03,  that the Company shall
have received an undertaking  satisfactory to it from the prospective  seller of
such Shares and from each  underwriter  of such Shares,  to  indemnify  and hold
harmless (in the same manner and to the same extent as set forth in  subdivision
(a) of this Section  11.05) the  Company,  each  director of the  Company,  each
officer of the Company who shall sign such registration statement and any person
who  controls  the Company  within the meaning of the Act,  with  respect to any
statement  or  omission  from  such  registration  statement,   any  preliminary
prospectus or final prospectus contained therein, or any amendment or supplement
thereto,  if such  statement  or  omission  was  made in  reliance  upon  and in
conformity  with  written  information  furnished  to  the  Company  through  an
instrument duly executed by such seller or underwriter  specifically  for use in
the preparation of such registration statement,  preliminary  prospectus,  final
prospectus, amendment, or supplement.

     (c)  Promptly  after  receipt  by an  indemnified  party of  notice  of the
commencement  of any  action  involving  a claim  referred  to in the  preceding
subdivisions of this Section 11.05,  such indemnified  party will, if a claim in
respect thereof is to be made against an indemnifying party, give written notice
to the latter of the  commencement of such action,  provided that the failure of
any indemnified  party to give notice as provided  therein shall not relieve the
indemnifying  party of its obligations under the preceding  subdivisions of this
Section 11.05. In case any such action is brought against an indemnified  party,
the  indemnifying  party will be  entitled to  participate  in and to assume the
defense thereof, jointly with any other indemnifying party similarly notified to
the  extent  that it may wish,  with  counsel  reasonably  satisfactory  to such
indemnified  party,  and  after  notice  from  the  indemnifying  party  to such
indemnified  party  of  its  election  so to  assume  the  defense  thereof  the
indemnifying party will not be liable to such indemnified party for any legal or
other  expenses  subsequently  incurred  by the  latter in  connection  with the
defense  thereof.  No  indemnifying  party,  in the defense of any such claim or
litigation, shall, except with the consent of each indemnified party, consent to
entry of any judgment or enter into any settlement  which does not include as an
unconditional  term  thereof  the giving by the  claimant or  plaintiff  to such
indemnified  party of a release  from all  liability in respect to such claim or
litigation.





<PAGE>



                               ARTICLE XII

                   CONSOLIDATION, MERGER, AND CONVEYANCE

     Section 12.01.  Continuation  of Terms of Agreement.  Nothing  contained in
this Agreement or in the accompanying  Debenture shall prevent any consolidation
or merger of the Company with or into any other  corporation or association,  or
any conveyance of the business, assets, and properties of the Company as a whole
or substantially as a whole, to any other corporation or other entity,  provided
that all  terms and  conditions  of this  Agreement,  including  payment,  to be
observed  and  performed  by the  Company  shall  be  expressly  assumed  by the
successor  entity  formed by or  resulting  from any such merger or to which any
such conveyance shall have been made.

     Section 12.02. Rights of Successor.  If the Company or any successor entity
is consolidated or merged with or into, or shall make a conveyance to, any other
corporation  or other entity,  as permitted and upon the terms  provided in this
Article XII, the entity formed by or resulting from such consolidation or merger
or to which  such  conveyance  shall  have been  made  shall  succeed  to and be
substituted  for the  Company,  with the same force and effect as if it had been
named in, and had executed,  this Agreement,  and shall have and possess and may
exercise,  subject to the terms and conditions of this Agreement, each and every
power, authority, and right herein reserved to or conferred upon the Company.

     Section 12.03. Construction. For every purpose of this Agreement, including
the execution and issuance of the Debenture, the term"Corporation"  includes and
means (unless the context otherwise  requires) not only the corporation that has
executed this Agreement,  but also any such successor  entity in accordance with
the provisions of this Article XII.

     Section  12.04.  Merger or Sale.  In the event of the merger or sale of the
Company as  described  in Section  3.04 of this  Agreement,  the  holders of the
Debentures  shall have the rights to cause the  Debentures  to be prepaid as set
forth in such Section 3.04.


                                 ARTICLE XIII

                              SPECIAL COVENANTS

     So long as,  but only so long as,  the  Debenture  is held by the  original
Holder, WEDGE Energy Services, L.L.C. ("WEDGE") or by an affiliate of WEDGE, the
Company shall be subject to the following special covenants:

     Section 13.01.  Right of Participation The Company grants to Holder a right
of  participation  to participate in any additional  equity  offerings which the
Company may offer,  as set forth in Sections  2.1,  2.2 and 2.3 of the  Purchase
Agreement.

     Section 13.02.  Restriction on Payment of Cash Dividends and Interest.  The
Company  agrees that so long as (i) the Debenture  remains  outstanding  or (ii)
Holder owns shares of preferred stock representing at least 10% of the shares of
capital stock of the Company on a fully  diluted  basis  utilizing the "treasury
method" as described in Section 2.3 of the Purchase Agreement,  it shall not pay
any cash dividends or any interest  accruals on any equity  security or any debt
security,  excluding any Superior  Indebtedness as defined in the Debenture,  in
existence  as of the date  hereof  or  created  hereafter  unless  and until the
Company's  earnings  before  deduction  of  interest,  taxes,  depreciation  and
amortization  ("EBITDA")  for the six (6) months  ended with the quarter for the
last  quarterly  report which the Company is required to furnish to Holder under
Section 4.01 of the Debenture  are more than 125% of the  Company's  obligations
for all dividends and interest due and payable on all outstanding  securities of
the Company as of such time.  The Company  agrees that interest  payments on the
Debenture  shall take  priority in payment over any  preferred  stock  dividends
payable to current holders of Series C Preferred Stock

     Section 13.03. Prohibition Against Capital Expenditures. The Company agrees
that so long as (i) the Debenture remains outstanding or (ii) Holder owns shares
of preferred  stock  representing at least 10% of the shares of capital stock of
the  Company  on a fully  diluted  basis  utilizing  the  "treasury  method"  as
described in Section 2.3 of the Purchase Agreement,  the Company will not incur,
or commit to incur, any capital  expenditures of any kind or nature in excess of
$50,000  without the approval of the Board of Directors of the Company,  and, in
addition, the Company agrees that, until the Company has expended the $2,500,000
in proceeds from the issuance of the Debenture, from the date hereof there shall
be no capital  expenditure in excess of $50,000 without the affirmative  written
consent of WEDGE or its affiliate who is then the Holder of the Debenture or any
security convertible thereto.

                                 ARTICLE XIV

                                  AMENDMENTS

     Section  14.01.  Without  Consent of  Holder.  The  Company  may amend this
Agreement and the Debenture without the consent of the Holder:

     (a)     To cure any ambiguity, defect, or inconsistency;

     (b) To comply with any  consolidation or merger of the Company with or into
any other corporation, or to comply with any conveyance of the business, assets,
and  properties of the Company as a whole or  substantially  as a whole,  to any
other corporation or other entity,  provided that the corporation  complies with
the terms of Article XII hereof; and

     (c) To make any  change  that does not  adversely  affect the rights of the
Holder.

     Section  14.02.  With  Consent of  Holder.  Subject to the terms of Section
14.01,  the Company may amend this Agreement or the  Debentures  with respect to
any matter  with the  written  consent of the holders of at least 66 2/3 percent
(66  2/3%) of the  aggregate  principal  amount of the  outstanding  Debentures.
However,  without  consent of each  holder  affected,  an  amendment  under this
section may not:

     (a) Reduce the rate of or change the time for  payment of  interest  on any
Debenture;

     (b) Reduce the principal of or change the fixed maturity of any Debenture;

     (c) Make  any  Debenture  convertible  into any  securities  other  than as
described in Section 8.01; or

     (d) Make any change in this Section 14.02.

     Section  14.03.  Revocation  and Effect of Consents.  Until an amendment or
waiver becomes effective, a consent to such amendment or waiver by a holder of a
Debenture is a continuing  consent by such holder and every subsequent holder of
such  Debenture,  even if notation of the consent is not made on any  Debenture.
Any such holder or subsequent holder may, however,  revoke the consent as to his
Debenture if the Company  receives the notice of revocation  before the date the
amendment or waiver becomes effective.  An amendment or waiver becomes effective
in accordance with its terms and thereafter binds every holder of a Debenture.

     Section 14.04. Notation on or Exchange of Debentures. The Company may place
an  appropriate  notation  concerning  an amendment  or waiver on any  Debenture
thereafter issued. The Company in exchange for all outstanding  certificates may
issue new certificates that reflect the amendment or waiver.


                                ARTICLE XV

                         MISCELLANEOUS PROVISIONS

     Section 15.01.  Notices.  Any notice or other communication  required to be
given  pursuant  to this  Agreement  must be in  writing  and  may be  given  by
registered or certified  mail,  and if given by  registered  or certified  mail,
shall be deemed to have been given and received  when a registered  or certified
letter  containing  such notice,  properly  addressed with postage  prepaid,  is
deposited in the United States mail;  and if given  otherwise than by registered
or certified  mail, it shall be deemed to have been given when  delivered to and
received  by the party to whom  addressed.  Such  notices  shall be given to the
parties hereto at the following addresses:




          If to the Company:

               TGC Industries, Inc.
               1304 Summit Avenue
               Suite 2
               Plano, TX  75074

                    With a Copy to:

               Vernon E. Rew, Jr.
               Law, Snakard & Gambill, P.C.
               3200 Bank One Tower
               500 Throckmorton
               Fort Worth, Texas  76102


<PAGE>



          If to the Holder:

               WEDGE Energy Services, L.L.C.
               1415 Louisiana

               Suite 3000
               Houston, Texas 77002
               Attention: President

               with a copy to:

               WEDGE Group Incorporated
               1415 Louisiana

               Suite 3000
               Houston, Texas 77002
               Attention: General Counsel

               With a Copy to:

               Darryl M. Burman
               DiCecco, Fant & Burman, L.L.P.
               3D/International Tower
               1900 West Loop South, Suite 1100
               Houston, Texas 77027

     or  addressed  to either  party at such other  address as such party  shall
hereafter  furnish to the other  party in  writing.  The address for any purpose
hereof may be changed at any time and shall be the most recent address furnished
in writing to the other party.

     Section 15.02. Binding Agreement.  This Agreement shall be binding upon and
inure  to  the  benefit  of the  parties  hereto  and  their  respective  heirs,
executors,  administrators,  legal  representatives,  successors,  and  assigns,
except as otherwise expressly provided herein.

     Section 15.03. Severability. If any one or more of the provisions contained
in this  Agreement  should for any  reason be held to be  invalid,  illegal,  or
unenforceable in any respect, such invalidity,  illegality,  or unenforceability
shall not  affect  any  other  provision  hereof,  and this  Agreement  shall be
construed as if such invalid, illegal, or unenforceable provision had never been
contained herein.

     Section 15.04.  No Third Parties.  Except as otherwise  expressly  provided
herein, nothing in this Agreement, expressed or implied, is intended or shall be
construed to confer upon or give to any person,  firm, or corporation other than
the  parties  hereto  and the  holders  from  time  to time of the  accompanying
Debenture any security,  rights, remedies, or claims, legal or equitable,  under
or by  reason  of  this  Agreement,  or  under  or by  reason  of any  covenant,
condition,  or  stipulation  herein  contained;  and this  Agreement and all the
covenants, conditions, and provisions herein contained are and shall be held for
the sole and exclusive  benefit of the parties  hereto and the holders from time
to time of the accompanying Debenture.

     Section  15.05.  Headings.  The  captions  used in  conjunction  with  this
Agreement  are for  convenience  only,  and  shall  not be deemed a part of this
Agreement or used to construe any provision hereof.

     Section 15.06. Survival of Representations,  Warranties, and Covenants. The
representations,  warranties,  and  covenants of the parties  shall  survive the
execution of this  Agreement  and the issuance of the Debenture and shall remain
in full force and effect thereafter.

     Section  15.07.  Entire  Agreement.  This  Agreement  and the  accompanying
Debenture  constitute  the sole and only  agreements  of the parties  hereto and
supersede any prior  understandings  or written or oral  agreements  between the
parties respecting the subject matter within.

     Section   15.08.   Inclusion  of  Debenture.   Reference  is  made  to  the
accompanying  Debenture.  The  provisions  of such  Debenture  shall  be  deemed
incorporated  into this  Agreement for all purposes as though fully set forth on
the face hereof.

     Section  15.09.  Immunities of  Stockholders,  Officers and  Directors.  No
recourse  shall be had for the  payment  of the  principal  of the  accompanying
Debenture  or of the  interest  thereon,  or for  any  claim  based  thereon  or
otherwise in respect thereof, or arising from this Agreement,  against any past,
present,  or future stockholder,  director,  or officer of the Company, as such,
whether  by  virtue  of any  constitution,  statute,  or rule of law,  or by the
enforcement  of any  assessment  or  penalty,  all such  liability  being by the
acceptance of the accompanying Debenture and as part of the consideration of the
issuance  thereof  expressly  waived  and  released  by  the  Holder  and by any
subsequent owners of the Debenture.

     Section 15.10.  Governing  Law. This  Agreement and the Debenture  shall be
governed by and construed in accordance with the laws of the State of Texas.

      IN WITNESS  WHEREOF,  the parties  hereto have caused this Agreement to be
duly executed as of the day and year first above written.

COMPANY:                                HOLDER:

TGC INDUSTRIES, INC.                    WEDGE ENERGY SERVICES, L.L.C.

By: /s/ Wayne A. Whitener                By:  /s/ Gregory J. Armstrong

    -------------------------------           ------------------------------
    Name:  Wayne Whitener                     Name:  Gregory J. Armstrong
    Title: President                          Title: Vice President


<PAGE>

















                                 EXHIBIT "A"


<PAGE>



                           TGC INDUSTRIES, INC.

               8 1/2% Convertible Subordinated Debenture, Series B
                            Due December 1, 2009

No. 01                                                     December 10, 1999

$2,500,000

     TGC  INDUSTRIES,  INC.,  a Texas  corporation  (the  "Company"),  for value
received, hereby promises to pay to the order of:

                        WEDGE ENERGY SERVICES, L.L.C.
                           or registered assigns

                      on the 1st day of December, 2009
                          the principal amount of

TWO MILLION FIVE HUNDRED THOUSAND DOLLARS ($2,500,000)

and to pay interest  (computed  on the basis of a 360-day year of twelve  30-day
months) on the principal amount from time to time remaining unpaid hereon at the
rate of eight and one-half percent (8 1/2%) per annum from the date hereof until
maturity,  and in accordance with the terms of that certain Debenture  Agreement
dated December 10, 1999,  calculated and payable semi-annually on December 1 and
June 1 in each year  commencing  with the first such date following the issuance
of this  Debenture,  and at  maturity.  The  Company  agrees to pay  interest on
overdue  principal  (including  any overdue  required or optional  prepayment of
principal),  and (to the extent legally  enforceable) on any overdue installment
of interest, at the rate of ten percent (10%) per annum after maturity,  whether
by acceleration or otherwise, until paid. Both the principal hereof and interest
hereon are payable at the principal  office of the Company in Plano,  Texas,  in
coin  or  currency  of the  United  States  of  America  which  at the  time  of
payment shall be legal tender for the payment of public and private debts.

     This  Debenture is issued under and pursuant to the terms and provisions of
that certain  Debenture  Agreement dated December 10, 1999,  entered into by the
Company with the original holder therein referred to, and this Debenture and the
holder  hereof is entitled  equally  and  ratably  with the holders of all other
Debentures,  if  any,  outstanding  under  the  Debenture  Agreement  to all the
benefits  provided  for  thereby or  referred  to  therein,  to which  Debenture
Agreement reference is hereby made for the statement thereof.

     This  Debenture and the other  Debentures,  if any,  outstanding  under the
Debenture  Agreement may be declared due prior to their expressed maturity dates
and voluntary  prepayments may be made thereon by the Company all in the events,
on the terms specified in the Debenture Agreement, and in the manner and amounts
as provided in the Debenture Agreement.

     This  Debenture  and  the  indebtedness  evidenced  hereby,  including  the
principal and interest,  shall at all times remain junior and subordinate to any
and all Superior Indebtedness as defined in the Debenture Agreement,  all on the
terms and to the extent more fully set forth in the Debenture Agreement.

     This   Debenture  is  registered  on  the  books  of  the  Company  and  is
transferable  only by surrender  thereof at the principal  office of the Company
duly endorsed or accompanied  by a written  instrument of transfer duly executed
by the registered  holder of this  Debenture or its attorney duly  authorized in
writing. Payment of or on account of principal, premium, if any, and interest of
this  Debenture  shall be made  only to or upon  the  order  in  writing  of the
registered holder.

                                        TGC INDUSTRIES, INC.

                                        By:  /s/ Wayne Whitener

                                             ------------------------------
                                        Name:     Wayne Whitener
                                        Title:    President

     THIS DEBENTURE HAS NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS
AMENDED  (THE "ACT") OR THE  SECURITIES  LAWS OF ANY STATE,  AND HAS BEEN ISSUED
PURSUANT TO EXEMPTIONS FROM SUCH  REGISTRATION AND  QUALIFICATION  REQUIREMENTS.
THIS DEBENTURE MAY NOT BE SOLD, TRANSFERRED,  OR ASSIGNED WITHOUT THE PERMISSION
OF THE ISSUER AND UNLESS THIS DEBENTURE  SHALL HAVE BEEN DULY  REGISTERED  UNDER
THE ACT AND REGISTERED OR QUALIFIED UNDER  APPLICABLE STATE SECURITIES LAWS, OR,
IN  THE  OPINION  OF  COUNSEL  SATISFACTORY  TO  THE  ISSUER,  REGISTRATION  AND
QUALIFICATION OF THE DEBENTURE SHALL NOT BE REQUIRED.  THIS DEBENTURE IS SUBJECT
TO AND ITS TRANSFER IS  RESTRICTED  BY THE TERMS AND  PROVISIONS OF THAT CERTAIN
DEBENTURE AGREEMENT,  DATED AS OF DECEMBER 10, 1999, EXECUTED BY AND BETWEEN THE
COMPANY  AND THE  HOLDER  OF THIS  DEBENTURE,  A COPY OF WHICH IS ON FILE IN THE
OFFICES OF THE COMPANY.





<PAGE>

















                               EXHIBIT 10.10

                  WARRANT AGREEMENTS AND WARRANT CERTIFICATES


<PAGE>



No. WT 1                                                    200,000 Warrants


                            VOID AFTER JULY 31, 2009
                    (unless extended by TGC Industries, Inc.)

                              TGC INDUSTRIES, INC.

                             Warrant Agreement and
                              Warrant Certificate

     I. A. THIS CERTIFIES THAT for value received J M S Inc. Cust FBO William J.
Barrett  Keogh,  or registered  assigns,  is the owner of the number of Warrants
("Warrants") of TGC Industries,  Inc.  (the"Company")  set forth above,  each of
which  entitles  the  owner  hereof to  purchase,  subject  to the  restrictions
referenced  herein,  prior to the close of  business on July 31,  2009,  or such
later date or dates as Company  may  determine  (the"Expiration  Date"),  at the
principal  office  of  the  Company,  one  (1)  share  of  Common  Stock  of TGC
Industries,  Inc.  (the"Shares"),  at the purchase price of $.30 per whole share
(the"Purchase   Price"),   upon  presentation  and  surrender  of  this  Warrant
Certificate  with the Form of Election to Purchase duly executed.  The number of
Warrants  evidenced by this Warrant  Certificate (and the number of Shares which
may be purchased upon exercise  thereof) set forth above is the number as of the
date of this Certificate,  based on the shares of Common Stock of the Company as
constituted at such date.

     B. No Warrant is exercisable by a holder unless, at the time of an exercise
by such  holder,  there is either (1) a  registration  statement  or  prospectus
covering  the Shares that is  effective  under the  Securities  Act of 1933,  as
amended,  and the securities  laws of the state of the address of record of such
holder;  or (2) an exemption  from  registration  is  available  for the Warrant
exercise  and the  issuance  of the Shares in the  opinion of counsel to Company
(and the holder  represents  in writing  that the Shares are being  acquired for
investment  and will not be  distributed  in violation of applicable  securities
laws).

          C. Except as hereafter  provided,] Company shall have no obligation to
register  either  the  Warrants  or the  Shares  into  which  the  Warrants  are
exercisable.

     (1) The Company  agrees  that,  upon  written  request  from the holders of
fifty-one percent (51%) of the then outstanding Warrants (including this Warrant
to the extent then outstanding),  it will take the following action with respect
to a public offering of the Shares,  considering the proposed  effective date of
such  offering,  subject to its ability to use currently  available  audited and
interim  financial   statements  without  having  to  have  any  such  financial
statements specially prepared for such offering:

     (a) promptly  cause to be prepared  and filed under the Act a  registration
statement and related  prospectus  relating to the public offering of the Shares
as may be required  for the lawful  public  offering  thereof in the manner then
contemplated;

     (b) use its best efforts, through its officers and directors, auditors, and
counsel in all matters  necessary or advisable to cause such to become effective
at the earliest possible date after the filing thereof;

     (c) deliver to the holder of this Warrant (to the extent then  outstanding)
such number of copies of such  prospectuses in preliminary and definitive  form,
and amendments thereto,  as it, he, or she may reasonably  require,  and Company
hereby  consents to the use of such  prospectuses  and amendments for the public
offering and sale of the Shares;

     (d) qualify the Shares for sale under applicable Blue Sky laws and continue
such qualification in effect so long as required for the purposes of the sale of
the Shares; and

     (e) pay all fees,  taxes,  and expenses  incident to the performance of its
obligations hereunder (except that each owner of such Shares will be responsible
for  payment of such  owner's own  attorneys'  fees,  Share  sales  commissions,
transfer taxes, and other expenses personal to such owner).

     (2) Following the (one time)  registration  of Shares upon written  request
from the holders of 51% of the then outstanding  Warrants as provided above, any
of the holders of the  remaining  Warrants may request the  registration  of the
remaining  Shares  issuable  upon the  exercise  thereof  (subject to  Company's
ability to use  currently  available  audited and interim  financial  statements
without having to have any such financial statements specially prepared for such
offering),  and Company  shall (at  Company's  own expense)  take the  necessary
action to register such Shares.

     (3) Whenever  Company,  at any time prior to the expiration of this Warrant
as herein  provided,  proposes to file with the Commission for the  registration
under the Act of any of its securities for Company's own benefit, Company shall,
at least thirty days prior to such filing, given written notice of such proposed
filing to the holder of this  Warrant at the last known  address of such holder,
and  shall  offer to  include  in such  filing  for  registration  any  proposed
disposition  of Shares  deliverable  upon the  exercise of the then  outstanding
Warrants,  upon  receipt  by  Company,  not less than  twenty  days prior to the
proposed  filing date, of a written request setting forth the facts with respect
to such proposed disposition.  If such request is made, Company will take action
(at  Company's  own expense) to register  such Shares by including  them in such
filing,  and will take such other  action as may be  requested by such holder to
qualify the Shares for sale under applicable Blue Sky laws.

     ----------------------

     THE  SECURITIES  REPRESENTED  BY THIS  CERTIFICATE  HAVE BEEN  ACQUIRED FOR
INVESTMENT ONLY AND HAVE NOT BEEN  REGISTERED  UNDER THE SECURITIES ACT OF 1933,
AS AMENDED, OR THE SECURITIES LAWS OF ANY STATE. WITHOUT SUCH REGISTRATION, SUCH
SECURITIES  MAY NOT BE SOLD OR  OTHERWISE  TRANSFERRED  AT ANY TIME  WHATSOEVER,
EXCEPT UPON DELIVERY TO THE CORPORATION OF AN OPINION OF COUNSEL SATISFACTORY TO
THE CORPORATION THAT REGISTRATION IS NOT REQUIRED FOR SUCH TRANSFER.

     II. The Purchase  Price,  the number of Shares which may be purchased  upon
the exercise of the Warrants  evidenced by this  Certificate,  and the number of
Warrants  outstanding  are subject to  modification  and adjustment from time to
time upon the occurrence of the events enumerated below:

     A. If and whenever the Company shall issue or sell any shares of its Common
Stock for a  consideration  per share  less  than the  Purchase  Price in effect
immediately  prior to the time of such issue or sale, then,  forthwith upon such
issue or sale, the Purchase Price shall be reduced to a price (calculated to the
nearest one  hundredth of a cent)  determined by dividing (1) an amount equal to
the sum of (a) the  number of shares of  Common  Stock  outstanding  immediately
prior to such issue or sale multiplied by the then existing  Purchase Price, and
(b) the consideration,  if any, received by the Company upon such issue or sale,
by (2) the total number of shares of Common Stock outstanding  immediately after
such issue or sale.

     B. For purposes of Subsection A. above,  the following  clauses (1) to (9),
inclusive, shall also be applicable:

     (1) In case at any time the  Company  shall grant  (whether  directly or by
assumption in a merger or otherwise) any rights to subscribe for or to purchase,
or any options for the  purchase  of,  Common  Stock or any stock or  securities
convertible  into  or  exchangeable  for  Common  Stock  (such   convertible  or
exchangeable  stock or securities  being herein called  Convertible  Securities)
whether or not such  rights or options or the right to convert or  exchange  any
such Convertible Securities are immediately exercisable, and the price per share
for which Common  Stock is issuable  upon the exercise of such rights or options
or upon  conversion or exchange of such  Convertible  Securities  (determined by
dividing (a) the total amount,  if any, received or receivable by the Company as
consideration  for the  granting  of such  rights or  options,  plus the minimum
aggregate  amount of  additional  consideration  payable to the Company upon the
exercise of such rights or options,  plus, in the case of such rights or options
which  relate  to  Convertible  Securities,  the  minimum  aggregate  amount  of
additional  consideration,  if  any,  payable  upon  the  issue  or sale of such
Convertible  Securities and upon the conversion or exchange thereof,  by (b) the
total  maximum  number of shares of Common Stock  issuable  upon the exercise of
such  rights  or  options  or  upon  the  conversion  or  exchange  of all  such
Convertible  Securities  issuable  upon the  exercise of such rights or options)
shall be less than the Purchase Price in effect immediately prior to the time of
the granting of such rights or options,  then the total maximum number of shares
of Common  Stock  issuable  upon the  exercise of such rights or options or upon
conversion  or  exchange  of  the  total  maximum  amount  of  such  Convertible
Securities issuable upon the exercise of such rights or options shall (as of the
date of granting of such rights or options) be deemed to be  outstanding  and to
have been  issued  for such price per share.  Except as  provided  in clause (3)
below,  no further  adjustments  of the  Purchase  Price  shall be made upon the
actual  issue  of such  Common  Stock  or of such  Convertible  Securities  upon
exercise of such rights or options or upon the actual issue of such Common Stock
or of such  Convertible  Securities  upon  exercise of such rights or options or
upon the  issue  of such  Common  Stock  upon  conversion  or  exchange  of such
Convertible Securities.

               (2) In case the  Company  shall  issue  (whether  directly  or by
assumption in a merger or otherwise) or sell any Convertible Securities, whether
or not the rights to exchange or convert thereunder are immediately exercisable,
and the price per share for which Common Stock is issuable upon such  conversion
or exchange  (determined by dividing (a) the total amount received or receivable
by the corporation as  consideration  for the issue or sale of such  Convertible
Securities,  plus the minimum aggregate amount of additional  consideration,  if
any, payable to the corporation upon the conversion or exchange thereof,  by (b)
the total maximum  number of shares of Common Stock issuable upon the conversion
or exchange of all such Convertible  Securities) shall be less than the Purchase
Price in effect  immediately  prior to the time of such issue or sale,  then the
total  maximum  number of shares of Common Stock  issuable  upon  conversion  or
exchange of all such  Convertible  Securities shall (as of the date of the issue
or sale of such Convertible  Securities) be deemed to be outstanding and to have
been  issued for such price per share,  provided  that (i) except as provided in
clause (3) below,  no further  adjustments  of the Purchase  Price shall be made
upon the actual issue of such Common Stock upon  conversion  or exchange of such
Convertible  Securities,  and (ii) if any such issue or sale of such Convertible
Securities  is made upon  exercise of any rights to subscribe for or to purchase
or any option to purchase any such Convertible  Securities for which adjustments
of the Purchase  Price have been or are to be made pursuant to other  provisions
of this Subsection B., no further adjustment of the Purchase Price shall be made
by reason of such issue or sale.

               (3) Upon the happening of any of the following events, namely, if
the purchase price  provided in any rights or options  referred to in clause (1)
of this Subsection B., the additional  consideration,  if any,  payable upon the
conversion or exchange of  Convertible  Securities  referred to in clause (1) or
clause  (2) of  this  Subsection  B.,  or the  rate  at  which  any  Convertible
Securities  referred to in clause (1) or clause (2) of this  Subsection  (B) are
convertible into or exchangeable for Common Stock shall change (other than under
or by reason of provisions  designed to protect against dilution),  the Purchase
Price in effect at the time of such event shall  forthwith be  readjusted to the
Purchase  Price  which  would have been in effect at such time had such  rights,
options or Convertible  Securities still  outstanding  provided for such changed
purchase price, additional consideration or conversion rate, as the case may be,
at the time initially granted, issued or sold; and on the expiration of any such
option or right or the termination of any such right to convert or exchange such
Convertible  Securities,  the  Purchase  Price  then in effect  hereunder  shall
forthwith be increased to the Purchase  Price which would have been in effect at
the time of such expiration or termination had such right, option or Convertible
Security,  to the extent  outstanding  immediately  prior to such  expiration or
termination,  never been issued, and the Common Stock issuable  thereunder shall
no longer be deemed to be outstanding. If the purchase price provided for in any
such right or option referred to in clause (1) of this Subsection B. or the rate
at which any Convertible  Securities  referred to in clause (1) or clause (2) of
this Subsection B. are convertible into or exchangeable into or exchangeable for
Common Stock,  shall decrease at any time under or by reason of provisions  with
respect  thereto  designed  to  protect  against  dilution,  then in case of the
delivery of Common  Stock upon the  exercise of any such right or option or upon
conversion or exchange of any such Convertible Security, the Purchase Price then
in effect  hereunder shall  forthwith be adjusted to such  respective  amount as
would have obtained had such rights,  option or Convertible  Security never been
issued as to such Common Stock and had  adjustments  been made upon the issuance
of the shares of Common Stock delivered as aforesaid, but only if as a result of
such  adjustment  the  Purchase  Price  then  in  effect  hereunder  is  thereby
decreased.

     (4) In case  the  Company  shall  declare  a  dividend  or make  any  other
distributions  upon  any  stock  of the  Company  payable  in  Common  Stock  or
Convertible Securities,  any Common Stock or Convertible Securities, as the case
may be, issuable in payment of such dividend or distribution  shall be deemed to
have been issued or sold without consideration.

     (5) In case any shares of Common  Stock or  Convertible  Securities  or any
rights or options to purchase  any such Common Stock or  Convertible  Securities
shall be issued or sold for cash, the  consideration  received therefor shall be
deemed to be the amount  received by the  Company  therefor,  without  deduction
therefrom  of  any  expenses   incurred  or  any  underwriting   commissions  or
concessions paid or allowed by the Company in connection therewith.  In case any
shares of Common  Stock or  Convertible  Securities  or any rights or options to
purchase any such Common Stock or Convertible Securities shall be issued or sold
for a consideration  other than cash, the amount of the consideration other than
cash  received  by the  Company  shall be  deemed  to be the fair  value of such
consideration  as  determined  in good  faith by the Board of  Directors  of the
Company,  without  deduction  of  any  expenses  incurred  or  any  underwriting
commissions  or  concessions  paid  or  allowed  by the  Company  in  connection
therewith.  In case any shares of Common Stock or Convertible  Securities or any
rights or options to purchase such Common Stock or Convertible  Securities shall
be issued in connection with any merger or consolidation in which the Company is
the surviving corporation,  the amount of consideration therefor shall be deemed
to be the fair value as  determined  by the Board of Directors of the Company of
such  portion of the assets and  business of the  non-surviving  corporation  or
corporations  as such Board shall  determine to be  attributable  to such Common
Stock or Convertible Securities, rights or options, as the case may be.

     (6) In case the  Company  shall take a record of the  holders of its Common
Stock for the  purpose of  entitling  them (a) to  receive a  dividend  or other
distribution  payable in Common Stock or in  Convertible  Securities,  or (b) to
subscribe  for or purchase  Common Stock or  Convertible  Securities,  then such
record date shall be deemed to be the date of the issue or sale of the shares of
Common Stock deemed to have been issued upon the declaration of such dividend or
the making of such other  distribution or the date of the granting of such right
of subscription or purchase, as the case may be.

     (7) The  number of shares of Common  Stock  outstanding  at any given  time
shall not include  shares owned or held or for the account of the  Company,  and
the  disposition  of any such  shares  shall be  considered  an issue or sale of
Common Stock for the purposes of Subsection B.

               (8) Anything in clause (5) of this  Subsection B. to the contrary
notwithstanding, in the case of an acquisition where all or part of the purchase
price is payable in Common Stock or  Convertible  Securities  but is stated as a
dollar amount, where the Company upon making the acquisition pays only part of a
maximum  dollar  purchase  price which is payable in Common Stock or Convertible
Securities  and where the  balance  of such  purchase  price is  deferred  or is
contingently  payable under a formula related to earnings over a period of time,
(a) the  consideration  received for any Common Stock or Convertible  Securities
delivered at the time of the acquisition  shall be deemed to be such part of the
total  consideration  as the portion of the dollar  purchase  price then paid in
Common  Stock or  Convertible  Securities  bears  to the  total  maximum  dollar
purchase price then paid in Common Stock or Convertible  Securities,  and (b) in
connection  with  each  issuance  of  additional  Common  Stock  or  Convertible
Securities  pursuant to the terms of the agreement relating to such acquisition,
the  consideration  received  shall  be  deemed  to be such  part  of the  total
consideration  as the portion of the dollar  purchase price then and theretofore
paid in Common Stock or Convertible Securities bears to the total maximum dollar
purchase price payable in Common Stock or Convertible Securities multiplied by a
fraction,  the  numerator of which shall be the number of shares (or in the case
of Convertible Securities other than stock, the aggregate principal amount) then
issued and the  denominator  of which shall be the total number of shares (or in
the case of Convertible  Securities  other than stock,  the aggregate  principal
amount) then and theretofore issued under such acquisition  agreement.  If it is
determined that any part of the deferred or contingent  portion of such purchase
price shall not be payable,  the Purchase Price then in effect  hereunder  shall
forthwith be readjusted to such Purchase Price as would have obtained (i) ha the
adjustment made in connection with such  acquisition been made upon the basis of
the  issuance  of only the  number  of shares  of  Common  Stock or  Convertible
Securities  actually  issued in connection with such  acquisition,  and (ii) had
adjustments  been made on the basis of the Purchase  Price as adjusted in clause
(1) for all issued or sale (as prices which would have  affected  such  adjusted
Purchase  Price) of Common Stock or rights,  options or  Convertible  Securities
made after such acquisition. In the event that only a part of the purchase price
for an  acquisition  is paid in Common Stock or  Convertible  Securities  in the
manner referred to in this clause (8), the term"total  consideration" as used in
this clause (8) shall mean that part of the aggregate consideration as is fairly
allocable to the purchase price paid in Common Stock or  Convertible  Securities
in the manner  referred to in this clause  (8),  as  determined  by the Board of
Directors of the Company.

     (9)  Notwithstanding  anything  to the  contrary  in this  Section  II., no
adjustment in the Purchase  Price shall result,  pursuant to Subsection A. above
or otherwise,  from the issuance by the Company of shares of its Common Stock as
a result of the following transactions:

     (a) The  exercise of options  heretofore  or  hereafter  granted  under the
Company's 1986 Incentive Stock Option Plan, as the same may be amended, extended
or substituted  from time to time provided,  that the number of shares available
thereunder   may  not  be  increased  by  any  such   amendment,   extension  or
substitution; and

     (b) The  exercise of options  heretofore  or  hereafter  granted  under the
Company's  1993 Stock  Option  Plan,  as the same may be  amended,  extended  or
substituted  from time to time  provided,  that the  number of shares  available
thereunder   may  not  be  increased  by  any  such   amendment,   extension  or
substitution.

     C. In case the  Company  shall  declare a dividend  upon the  Common  Stock
payable  otherwise  than out of  consolidated  earnings or  consolidated  earned
surplus, determined in accordance with generally accepted accounting principles,
including the making of appropriate deductions for minority interest, if any, in
subsidiary  corporations,  and  otherwise  than in Common  Stock or  Convertible
Securities,  the Company shall give the holders of each Warrant thirty (30) days
prior  written  notice of the date as of which the  holders  of Common  Stock of
record entitled to such special  dividend shall be determined.  For the purposes
of the foregoing a dividend  other than in cash shall be considered  payable out
of earnings or surplus (other than  revaluation or paid-in  surplus) only to the
extent that such  earnings  or surplus  are charged an amount  equal to the fair
value of such dividend as determined by the Board of Directors of the Company.

     D. (1) In case the  Company  shall at any time  subdivide  its  outstanding
shares of Common Stock into a greater  number of shares,  the Purchase  Price in
effect immediately prior to such subdivision shall be  proportionately  reduced,
and,  conversely  (2) in case the  outstanding  shares  of  Common  Stock of the
Company shall be combined into a smaller number of shares, the Purchase Price in
effect immediately prior to such combination shall be proportionately increased.

     E. In case of any capital  reorganization  or any  reclassification  of the
Common Stock of the Company,  the consolidation of Company with or the merger of
Company with or into any other  corporation,  or the sale of the  properties and
assets of Company as, or substantially as, an entirety to any other corporation,
then each  holder of a Warrant  then  outstanding  shall be entitled to purchase
such number of shares of stock or other securities or property of Company or any
other  corporation   resulting  from  such   reorganization,   reclassification,
consolidation,  merger,  or sale,  as was  exchanged for the number of shares of
Common Stock of Company  which the holder  would have been  entitled to purchase
except for such action. The subdivision or combination of shares of Common Stock
at any time  outstanding  into a greater  or  lesser  number of shares of Common
Stock  shall not be  deemed  to be a  reclassification  of the  Common  Stock of
Company for the purposes of this Subsection"E."

     F. (1) Except as provided in Subsection G, to follow,  upon each adjustment
of the  Purchase  Price as a result of (a) an issuance  or sale of Common  Stock
below the Purchase  Price as provided in  Subsections  A and B above,  including
(without  limitation) a dividend or  distribution in shares of capital stock, or
(b) a  subdivision  of  outstanding  shares  of  Common  Stock  as  provided  in
Subsection "D.(1)" hereof, the number of shares of Common Stock purchasable upon
exercise of any Warrant  Certificate  shall be increased to the number of shares
of Common Stock  (calculated to the nearest  hundredth)  obtained by multiplying
(i) the number of shares of Common Stock  purchasable  immediately prior to such
adjustment upon exercise of Warrants  (evidenced by the Warrant Certificate held
by such holder) by (ii) the Purchase Price in effect  immediately  prior to such
adjustment, and dividing the product so obtained by the Purchase Price in effect
after such adjustment.

     (2) Except as provided in Subsection "G" to follow, upon each adjustment of
the Purchase  Price as a result of a combination of the Common Stock as provided
in Subsection  "D.(2)" hereof,  the number of shares of Common Stock purchasable
upon  exercise of any Warrant  Certificate  shall be  decreased to the number of
shares of  Common  Stock  (calculated  to the  nearest  hundredth)  obtained  by
multiplying  (a) the number of shares of Common  Stock  purchasable  immediately
prior to such  adjustment  upon  exercise of Warrants  evidenced  by the Warrant
Certificate held by such holder, by (b) the Purchase Price in effect immediately
prior to such  adjustment,  and then  dividing  the  product so  obtained by the
Purchase Price in effect after such adjustment.

     G. In lieu of an adjustment  in the number of shares  covered by a Warrant,
Company may elect, on or after the date of any adjustment of the Purchase Price,
to adjust the number of Warrants.

     H.  Irrespective  of any adjustments or change in the Purchase Price or the
number of shares of the Common Stock issuable upon the exercise of the Warrants,
the Warrant  Certificates  theretofore  and  thereafter  issued may  continue to
express  the  Purchase  Price  per share and the  number  of shares  which  were
expressed upon the Warrant Certificates when initially issued.

     I. Before  taking any action which would cause an  adjustment  reducing the
Purchase  Price below the then par value,  if any, of the shares of Common Stock
issuable upon exercise of the Warrants,  Company shall take any corporate action
which may, in the opinion of its counsel, be necessary in order that Company may
validly and legally  issue  fully paid and  nonassessable  shares of such Common
Stock at such adjusted Purchase Price.

     J.  Whenever  the  Purchase  Price,  the  number of shares of Common  Stock
issuable  upon the  exercise  of each  Warrant,  or the number of  Warrants  are
adjusted as provided in this  Section  II.,  Company  shall  promptly  prepare a
certificate  setting  forth the  Purchase  Price as so  adjusted,  the number of
shares  of  Common  Stock  issuable  upon the  exercise  of each  Warrant  as so
adjusted, and a brief statement of the facts accounting for such adjustment.

     K. If any event occurs as to which in the opinion of the Board of Directors
of the  Company  the other  provisions  of this  Section  II.  are not  strictly
applicable or if strictly  applicable  would not fairly  protect the  conversion
rights of the holders of the Warrants in accordance  with the  essential  intent
and  principles of such  provisions,  then the Board of Directors  shall make an
adjustment  in the  application  of such  provisions,  in  accordance  with such
essential  intent and  principles,  so as to  protect  such  exercise  rights as
aforesaid.

     III. A. This Certificate, with or without other Warrant Certificates,  upon
surrender at the principal  office of the Company,  may be exchanged for another
Warrant  Certificate or Warrant  Certificates of like tenor evidencing  Warrants
entitling  the  holder  to  purchase  a like  aggregate  number of Shares as the
Warrants   evidenced  by  the  Warrant   Certificate  or  Warrant   Certificates
surrendered.  If only a part of the Warrants  evidenced by this  Certificate are
exercised,  the holder  hereof  shall be  entitled to  receive,  upon  surrender
hereof,  another Warrant  Certificate or Warrant  Certificates for the number of
whole Warrants not exercised.

     B. Upon receipt by Company of evidence reasonably satisfactory to it of the
loss, theft, destruction,  or mutilation of a Warrant Certificate,  and, in case
of loss, theft, destruction,  or mutilation, of indemnity or security reasonably
satisfactory  to it, and  reimbursement  to Company of all  reasonable  expenses
incidental  thereto,  and upon surrender to the Company and  cancellation of the
Warrant Certificate,  if mutilated,  the Company shall deliver to the registered
owner a new Warrant Certificate in lieu of, and evidencing the right to purchase
the same  number  of  shares  as,  the  Warrant  Certificate  so  lost,  stolen,
destroyed, or mutilated.

     C. No  holder  of the  Warrants  evidenced  by this  Certificate  shall  be
entitled to vote or receive  dividends  or be deemed the holder of Shares or any
other securities of Company which may at any time be issuable on the exercise of
these  Warrants for any  purpose,  nor shall  anything  contained in the Warrant
Agreement or herein be construed to confer upon the holder of these Warrants, as
such, any of the rights of a shareholder of Company or any right to vote for the
election  of  directors  or upon any matter  submitted  to  shareholders  at any
meeting thereof, or to give or withhold consent to any corporate action (whether
upon any recapitalization,  issue of stock, reclassification of stock, change of
par value, consolidation, merger, conveyance, or otherwise) or to receive notice
of meetings, or to receive dividends or subscription rights or otherwise,  until
the Warrants  evidenced by this Warrant  Certificate have been exercised and the
Common Stock purchasable upon the exercise thereof has become deliverable.

     D. To the extent that any Warrant  Certificates  remain outstanding at 5:01
P.M.  central  standard time on the Expiration  Date, such  outstanding  Warrant
Certificates  shall be  automatically  deemed exercised on behalf of each record
holder of Warrant  Certificates into shares of the Company's Common Stock at the
rate ("Conversion Rate") of one-tenth (1/10) of a share of Common Stock for each
Warrant  Certificate  or  Certificates  representing,   immediately  before  the
Expiration Date, the right to purchase one share of Common Stock.

     E.  Upon  the  exercise  of the  Warrant,  in lieu of the  issuance  of any
fractional  Shares,  the Company shall pay cash to the registered  holder of the
Warrant based on the  difference  between the market price of the Shares,  which
price  shall be  computed  as the per Share  closing  price (if such  Shares are
listed on an exchange) or the average between the per Share bid and asked prices
as of the close of business  on the  exercise  date as reported by the  National
Association of Securities  Dealers  Automated  Quotation System and the Purchase
Price on the exercise date times the  fractional  Share which is  represented by
the Warrants on the exercise date.  However, if no market price exists, then the
amount of cash to be paid to the registered holder of the Warrant in lieu of any
fractional  Shares shall be the product of the difference  between the per share
Tangible  Net Book Value  (defined  hereafter)  of the  shares of the  Company's
Common Stock outstanding on the last business day prior to the exercise date and
the Purchase  Price on the exercise  date times the  fractional  security  which
otherwise  would  have been  issuable  in the  absence  of this  provision.  For
purposes of payment of cash in lieu of the  issuance of  fractional  securities,
the  term"Tangible  Net Book Value" means the consolidated  total  shareholders'
equity,  determined in accordance with generally accepted accounting  principles
("GAAP"), less the aggregate net amount of the following items to the extent, if
any,  that  they  were  included  in   consolidated   assets  or  deducted  from
consolidated liabilities in computing shareholders' equity:

     (i) all franchises,  licenses,  patents,  patent applications,  copyrights,
trademarks,  trade names,  goodwill,  experimental  or  organizational  expense,
unamortized debt discount and expense, and all other assets which under GAAP are
deemed intangible; and,

     (ii) any write-up of assets after December 31, 1998.

          F. The holder  hereof,  by  accepting  same,  consents and agrees with
Company and with every other holder of a Warrant Certificate that:

     (1) The Warrants evidenced by this Certificate are transferable only on the
registry  books  of the  Company  upon  surrender  of  this  Certificate  at the
principal office of the Company and only as provided below;

     (2)  Company  and may  deem  and  treat  the  person  in  whose  name  this
Certificate  is  registered  as the absolute  owner  thereof and of the Warrants
evidenced thereby  (notwithstanding any notations of ownership or writing on the
Certificate made by anyone other than Company) for all purposes whatsoever,  and
the Company shall not be affected by any notice to the contrary; and

               (3)  Company  may  modify the terms of the  Warrant  from time to
time.

     G. The  registered  holder of any Warrant  Certificate  may  exercise it in
whole or in part at any time,  but only in such  multiples  as are  required  to
permit the  issuance  by  Company of one or more  shares,  by  surrender  of the
Warrant  Certificate  with the form of election to purchase on the reverse  side
thereof duly executed,  to the Company at the principal office of the Company at
or prior to 5:00 P.M. central standard time on July 31, 2009, or such later date
or dates as Company may determine  together with payment of the Purchase  Price,
payable to Company, for each share into which the Warrants are exercised.

     H. Upon  receipt of a Warrant  Certificate,  with the form of  election  to
purchase duly  executed,  accompanied  by payment of the Purchase  Price for its
shares to be  purchased  and an amount equal to any  applicable  transfer tax in
cash,  or by  certified  check,  bank  draft,  or postal or express  money order
payable  to the  order  of  Company,  the  Company  shall  thereupon  cause  the
certificates  for the number of whole  shares to be purchased to be delivered to
or  upon  the  order  of the  registered  holder  of  such  Warrant  Certificate
registered in such name or names as may be designated by such holder.

     I. In case the registered holder of any Warrant Certificate  exercises less
than all the Warrants evidenced thereby,  a new Warrant  Certificate  evidencing
Warrants  equivalent to the Warrants  remaining  unexercised  shall be issued by
Warrant Agent to the  registered  holder of such Warrant  Certificate or to such
holder's duly authorized assigns.

     J. Each person in whose name any  certificate for shares of Common Stock of
the Company is issued upon the  exercise of Warrants  shall for all  purposes be
deemed  to have  become  the  holder of  record  of the  shares of Common  Stock
represented thereby on, and such certificate shall be dated, the date upon which
the Warrant  Certificate  evidencing  such  Warrants  was duly  surrendered  and
payment of the  Purchase  Price (and any  applicable  transfer  taxes) was made;
provided, however, that if the date of such surrender and payment is a date upon
which the transfer  books of Company are closed,  such person shall be deemed to
have become the record holder of such shares on, and such  certificate  shall be
dated,  the next succeeding  business day on which the transfer books of Company
are open. Prior to the exercise of the Warrants evidenced thereby, the holder of
a Warrant  Certificate  shall not be entitled to any rights of a shareholder  of
Company  with  respect  to  shares  for  which  the  Warrants  are  exercisable,
including,  without limitation, the right to vote, to receive dividends or other
distributions,  or to exercise any preemptive  rights, and shall not be entitled
to receive any notice of any proceedings of Company, except as provided herein.

          WITNESS the facsimile signatures of the proper officers of Company and
its corporate seal. Dated as of July 30, 1999.

                                   TGC INDUSTRIES, INC.

                                   /s/ WAYNE A. WHITENER
                                   ____________________________
                                   Wayne A. Whitener, President


ATTEST:


By:    /s/ Kenneth W. Uselton

       _______________________________
          Kenneth W. Uselton,
         Assistant Secretary




<PAGE>




                                  ASSIGNMENT

                (To be executed by the registered holder if such
               holder desires to transfer the Warrant Certificate)

     FOR  VALUE  RECEIVED  _____________________________________  hereby  sells,
assigns, and transfers unto ______________________

                  (Please print name and address of transferee)

- ------------------------------------------------------------------
this Warrant Certificate,  together with all right, title, and interest therein,
and does hereby irrevocably  constitute and appoint  ___________________________
Attorney,  to  transfer  the  within  Warrant  Certificate  on the  books of the
within-named Company, with full power of substitution.

Dated: ________________________ , 19____.

                                        -------------------------
                                                       Signature

                                        -------------------------
                                             Signature Guaranteed

     NOTICE:  The  signature(s)  to this  assignment  must  correspond  with the
name(s) as written upon the face of the Certificate in every particular  without
alteration  or  enlargement  or  any  change  whatever.   Signature(s)  must  be
guaranteed  by a  commercial  bank or trust  company or a member firm of a major
stock exchange.






<PAGE>




     ELECTION TO PURCHASE

     (To be executed if holder desires
     to exercise the Warrant Certificate)
     To: TGC INDUSTRIES, INC.

          The undersigned hereby irrevocably elects to exercise ________________
Warrants  represented  by this  Warrant  Certificate  to purchase  the shares of
Common  Stock  issuable  upon the exercise of such  Warrants  and requests  that
certificates for such shares be issued in the name of:

- ------------------------------------------------------------------
     (Please insert social security or other identifying number)

- ------------------------------------------------------------------
     (Please print name and address)

          If such number of Warrants  does not  constitute  all of the  Warrants
evidenced by this Warrant Certificate, a new Warrant Certificate for the balance
remaining of such Warrants shall be registered in the name of and delivered to:

- ------------------------------------------------------------------
     (Please insert social security or other identifying number)

- ------------------------------------------------------------------

Dated: ____________________, 19_________

                                        -------------------------
                                                       Signature

                                        -------------------------
                                           Signature Guaranteed

     NOTICE:  The signature on this Form of Election to Purchase must correspond
with the name(s) as written upon the face of the Certificate  without alteration
or  enlargement  or any change  whatever.  Signature(s)  must be guaranteed by a
commercial bank or trust company or a member firm of a major stock exchange.




<PAGE>




No. WT 2                                                    200,000 Warrants


                       VOID  AFTER  JULY  31,  2009
                   (unless extended by TGC Industries, Inc.)

                          TGC INDUSTRIES, INC.

                         Warrant Agreement and
                          Warrant Certificate

     I. A. THIS CERTIFIES THAT for value received Edward L. Flynn, or registered
assigns, is the owner of the number of Warrants  ("Warrants") of TGC Industries,
Inc.  (the"Company") set forth above, each of which entitles the owner hereof to
purchase,  subject to the restrictions  referenced herein, prior to the close of
business on July 31, 2009,  or such later date or dates as Company may determine
(the"Expiration Date"), at the principal office of the Company, one (1) share of
Common Stock of TGC  Industries,  Inc.  (the"Shares"),  at the purchase price of
$.30 per whole share (the"Purchase  Price"),  upon presentation and surrender of
this Warrant  Certificate  with the Form of Election to Purchase duly  executed.
The number of Warrants evidenced by this Warrant  Certificate (and the number of
Shares  which may be  purchased  upon  exercise  thereof) set forth above is the
number as of the date of this  Certificate,  based on the shares of Common Stock
of the Company as constituted at such date.

     B. No Warrant is exercisable by a holder unless, at the time of an exercise
by such  holder,  there is either (1) a  registration  statement  or  prospectus
covering  the Shares that is  effective  under the  Securities  Act of 1933,  as
amended,  and the securities  laws of the state of the address of record of such
holder;  or (2) an exemption  from  registration  is  available  for the Warrant
exercise  and the  issuance  of the Shares in the  opinion of counsel to Company
(and the holder  represents  in writing  that the Shares are being  acquired for
investment  and will not be  distributed  in violation of applicable  securities
laws).

          C. Except as hereafter  provided,] Company shall have no obligation to
register  either  the  Warrants  or the  Shares  into  which  the  Warrants  are
exercisable.

     (1) The Company  agrees  that,  upon  written  request  from the holders of
fifty-one percent (51%) of the then outstanding Warrants (including this Warrant
to the extent then outstanding),  it will take the following action with respect
to a public offering of the Shares,  considering the proposed  effective date of
such  offering,  subject to its ability to use currently  available  audited and
interim  financial   statements  without  having  to  have  any  such  financial
statements specially prepared for such offering:

     (a) promptly  cause to be prepared  and filed under the Act a  registration
statement and related  prospectus  relating to the public offering of the Shares
as may be required  for the lawful  public  offering  thereof in the manner then
contemplated;

     (b) use its best efforts, through its officers and directors, auditors, and
counsel in all matters  necessary or advisable to cause such to become effective
at the earliest possible date after the filing thereof;

     (c) deliver to the holder of this Warrant (to the extent then  outstanding)
such number of copies of such  prospectuses in preliminary and definitive  form,
and amendments thereto,  as it, he, or she may reasonably  require,  and Company
hereby  consents to the use of such  prospectuses  and amendments for the public
offering and sale of the Shares;

     (d) qualify the Shares for sale under applicable Blue Sky laws and continue
such qualification in effect so long as required for the purposes of the sale of
the Shares; and

     (e) pay all fees,  taxes,  and expenses  incident to the performance of its
obligations hereunder (except that each owner of such Shares will be responsible
for  payment of such  owner's own  attorneys'  fees,  Share  sales  commissions,
transfer taxes, and other expenses personal to such owner).

     (2) Following the (one time)  registration  of Shares upon written  request
from the holders of 51% of the then outstanding  Warrants as provided above, any
of the holders of the  remaining  Warrants may request the  registration  of the
remaining  Shares  issuable  upon the  exercise  thereof  (subject to  Company's
ability to use  currently  available  audited and interim  financial  statements
without having to have any such financial statements specially prepared for such
offering),  and Company  shall (at  Company's  own expense)  take the  necessary
action to register such Shares.

     (3) Whenever  Company,  at any time prior to the expiration of this Warrant
as herein  provided,  proposes to file with the Commission for the  registration
under the Act of any of its securities for Company's own benefit, Company shall,
at least thirty days prior to such filing, given written notice of such proposed
filing to the holder of this  Warrant at the last known  address of such holder,
and  shall  offer to  include  in such  filing  for  registration  any  proposed
disposition  of Shares  deliverable  upon the  exercise of the then  outstanding
Warrants,  upon  receipt  by  Company,  not less than  twenty  days prior to the
proposed  filing date, of a written request setting forth the facts with respect
to such proposed disposition.  If such request is made, Company will take action
(at  Company's  own expense) to register  such Shares by including  them in such
filing,  and will take such other  action as may be  requested by such holder to
qualify the Shares for sale under applicable Blue Sky laws.

     ----------------------

     THE  SECURITIES  REPRESENTED  BY THIS  CERTIFICATE  HAVE BEEN  ACQUIRED FOR
INVESTMENT ONLY AND HAVE NOT BEEN  REGISTERED  UNDER THE SECURITIES ACT OF 1933,
AS AMENDED, OR THE SECURITIES LAWS OF ANY STATE. WITHOUT SUCH REGISTRATION, SUCH
SECURITIES  MAY NOT BE SOLD OR  OTHERWISE  TRANSFERRED  AT ANY TIME  WHATSOEVER,
EXCEPT UPON DELIVERY TO THE CORPORATION OF AN OPINION OF COUNSEL SATISFACTORY TO
THE CORPORATION THAT REGISTRATION IS NOT REQUIRED FOR SUCH TRANSFER.

     II. The Purchase  Price,  the number of Shares which may be purchased  upon
the exercise of the Warrants  evidenced by this  Certificate,  and the number of
Warrants  outstanding  are subject to  modification  and adjustment from time to
time upon the occurrence of the events enumerated below:

     A. If and whenever the Company shall issue or sell any shares of its Common
Stock for a  consideration  per share  less  than the  Purchase  Price in effect
immediately  prior to the time of such issue or sale, then,  forthwith upon such
issue or sale, the Purchase Price shall be reduced to a price (calculated to the
nearest one  hundredth of a cent)  determined by dividing (1) an amount equal to
the sum of (a) the  number of shares of  Common  Stock  outstanding  immediately
prior to such issue or sale multiplied by the then existing  Purchase Price, and
(b) the consideration,  if any, received by the Company upon such issue or sale,
by (2) the total number of shares of Common Stock outstanding  immediately after
such issue or sale.

     B. For purposes of Subsection A. above,  the following  clauses (1) to (9),
inclusive, shall also be applicable:

               (1) In case at any time the Company shall grant (whether directly
or by  assumption  in a merger or  otherwise)  any rights to subscribe for or to
purchase,  or any  options for the  purchase  of,  Common  Stock or any stock or
securities  convertible into or exchangeable for Common Stock (such  convertible
or exchangeable stock or securities being herein called Convertible  Securities)
whether or not such  rights or options or the right to convert or  exchange  any
such Convertible Securities are immediately exercisable, and the price per share
for which Common  Stock is issuable  upon the exercise of such rights or options
or upon  conversion or exchange of such  Convertible  Securities  (determined by
dividing (a) the total amount,  if any, received or receivable by the Company as
consideration  for the  granting  of such  rights or  options,  plus the minimum
aggregate  amount of  additional  consideration  payable to the Company upon the
exercise of such rights or options,  plus, in the case of such rights or options
which  relate  to  Convertible  Securities,  the  minimum  aggregate  amount  of
additional  consideration,  if  any,  payable  upon  the  issue  or sale of such
Convertible  Securities and upon the conversion or exchange thereof,  by (b) the
total  maximum  number of shares of Common Stock  issuable  upon the exercise of
such  rights  or  options  or  upon  the  conversion  or  exchange  of all  such
Convertible  Securities  issuable  upon the  exercise of such rights or options)
shall be less than the Purchase Price in effect immediately prior to the time of
the granting of such rights or options,  then the total maximum number of shares
of Common  Stock  issuable  upon the  exercise of such rights or options or upon
conversion  or  exchange  of  the  total  maximum  amount  of  such  Convertible
Securities issuable upon the exercise of such rights or options shall (as of the
date of granting of such rights or options) be deemed to be  outstanding  and to
have been  issued  for such price per share.  Except as  provided  in clause (3)
below,  no further  adjustments  of the  Purchase  Price  shall be made upon the
actual  issue  of such  Common  Stock  or of such  Convertible  Securities  upon
exercise of such rights or options or upon the actual issue of such Common Stock
or of such  Convertible  Securities  upon  exercise of such rights or options or
upon the  issue  of such  Common  Stock  upon  conversion  or  exchange  of such
Convertible Securities.

               (2) In case the  Company  shall  issue  (whether  directly  or by
assumption in a merger or otherwise) or sell any Convertible Securities, whether
or not the rights to exchange or convert thereunder are immediately exercisable,
and the price per share for which Common Stock is issuable upon such  conversion
or exchange  (determined by dividing (a) the total amount received or receivable
by the corporation as  consideration  for the issue or sale of such  Convertible
Securities,  plus the minimum aggregate amount of additional  consideration,  if
any, payable to the corporation upon the conversion or exchange thereof,  by (b)
the total maximum  number of shares of Common Stock issuable upon the conversion
or exchange of all such Convertible  Securities) shall be less than the Purchase
Price in effect  immediately  prior to the time of such issue or sale,  then the
total  maximum  number of shares of Common Stock  issuable  upon  conversion  or
exchange of all such  Convertible  Securities shall (as of the date of the issue
or sale of such Convertible  Securities) be deemed to be outstanding and to have
been  issued for such price per share,  provided  that (i) except as provided in
clause (3) below,  no further  adjustments  of the Purchase  Price shall be made
upon the actual issue of such Common Stock upon  conversion  or exchange of such
Convertible  Securities,  and (ii) if any such issue or sale of such Convertible
Securities  is made upon  exercise of any rights to subscribe for or to purchase
or any option to purchase any such Convertible  Securities for which adjustments
of the Purchase  Price have been or are to be made pursuant to other  provisions
of this Subsection B., no further adjustment of the Purchase Price shall be made
by reason of such issue or sale.

               (3) Upon the happening of any of the following events, namely, if
the purchase price  provided in any rights or options  referred to in clause (1)
of this Subsection B., the additional  consideration,  if any,  payable upon the
conversion or exchange of  Convertible  Securities  referred to in clause (1) or
clause  (2) of  this  Subsection  B.,  or the  rate  at  which  any  Convertible
Securities  referred to in clause (1) or clause (2) of this  Subsection  (B) are
convertible into or exchangeable for Common Stock shall change (other than under
or by reason of provisions  designed to protect against dilution),  the Purchase
Price in effect at the time of such event shall  forthwith be  readjusted to the
Purchase  Price  which  would have been in effect at such time had such  rights,
options or Convertible  Securities still  outstanding  provided for such changed
purchase price, additional consideration or conversion rate, as the case may be,
at the time initially granted, issued or sold; and on the expiration of any such
option or right or the termination of any such right to convert or exchange such
Convertible  Securities,  the  Purchase  Price  then in effect  hereunder  shall
forthwith be increased to the Purchase  Price which would have been in effect at
the time of such expiration or termination had such right, option or Convertible
Security,  to the extent  outstanding  immediately  prior to such  expiration or
termination,  never been issued, and the Common Stock issuable  thereunder shall
no longer be deemed to be outstanding. If the purchase price provided for in any
such right or option referred to in clause (1) of this Subsection B. or the rate
at which any Convertible  Securities  referred to in clause (1) or clause (2) of
this Subsection B. are convertible into or exchangeable into or exchangeable for
Common Stock,  shall decrease at any time under or by reason of provisions  with
respect  thereto  designed  to  protect  against  dilution,  then in case of the
delivery of Common  Stock upon the  exercise of any such right or option or upon
conversion or exchange of any such Convertible Security, the Purchase Price then
in effect  hereunder shall  forthwith be adjusted to such  respective  amount as
would have obtained had such rights,  option or Convertible  Security never been
issued as to such Common Stock and had  adjustments  been made upon the issuance
of the shares of Common Stock delivered as aforesaid, but only if as a result of
such  adjustment  the  Purchase  Price  then  in  effect  hereunder  is  thereby
decreased.

     (4) In case  the  Company  shall  declare  a  dividend  or make  any  other
distributions  upon  any  stock  of the  Company  payable  in  Common  Stock  or
Convertible Securities,  any Common Stock or Convertible Securities, as the case
may be, issuable in payment of such dividend or distribution  shall be deemed to
have been issued or sold without consideration.

               (5) In case any shares of Common Stock or Convertible  Securities
or any  rights or options  to  purchase  any such  Common  Stock or  Convertible
Securities shall be issued or sold for cash, the consideration received therefor
shall be deemed to be the  amount  received  by the  Company  therefor,  without
deduction therefrom of any expenses incurred or any underwriting  commissions or
concessions paid or allowed by the Company in connection therewith.  In case any
shares of Common  Stock or  Convertible  Securities  or any rights or options to
purchase any such Common Stock or Convertible Securities shall be issued or sold
for a consideration  other than cash, the amount of the consideration other than
cash  received  by the  Company  shall be  deemed  to be the fair  value of such
consideration  as  determined  in good  faith by the Board of  Directors  of the
Company,  without  deduction  of  any  expenses  incurred  or  any  underwriting
commissions  or  concessions  paid  or  allowed  by the  Company  in  connection
therewith.  In case any shares of Common Stock or Convertible  Securities or any
rights or options to purchase such Common Stock or Convertible  Securities shall
be issued in connection with any merger or consolidation in which the Company is
the surviving corporation,  the amount of consideration therefor shall be deemed
to be the fair value as  determined  by the Board of Directors of the Company of
such  portion of the assets and  business of the  non-surviving  corporation  or
corporations  as such Board shall  determine to be  attributable  to such Common
Stock or Convertible Securities, rights or options, as the case may be.

     (6) In case the  Company  shall take a record of the  holders of its Common
Stock for the  purpose of  entitling  them (a) to  receive a  dividend  or other
distribution  payable in Common Stock or in  Convertible  Securities,  or (b) to
subscribe  for or purchase  Common Stock or  Convertible  Securities,  then such
record date shall be deemed to be the date of the issue or sale of the shares of
Common Stock deemed to have been issued upon the declaration of such dividend or
the making of such other  distribution or the date of the granting of such right
of subscription or purchase, as the case may be.

     (7) The  number of shares of Common  Stock  outstanding  at any given  time
shall not include  shares owned or held or for the account of the  Company,  and
the  disposition  of any such  shares  shall be  considered  an issue or sale of
Common Stock for the purposes of Subsection B.

               (8) Anything in clause (5) of this  Subsection B. to the contrary
notwithstanding, in the case of an acquisition where all or part of the purchase
price is payable in Common Stock or  Convertible  Securities  but is stated as a
dollar amount, where the Company upon making the acquisition pays only part of a
maximum  dollar  purchase  price which is payable in Common Stock or Convertible
Securities  and where the  balance  of such  purchase  price is  deferred  or is
contingently  payable under a formula related to earnings over a period of time,
(a) the  consideration  received for any Common Stock or Convertible  Securities
delivered at the time of the acquisition  shall be deemed to be such part of the
total  consideration  as the portion of the dollar  purchase  price then paid in
Common  Stock or  Convertible  Securities  bears  to the  total  maximum  dollar
purchase price then paid in Common Stock or Convertible  Securities,  and (b) in
connection  with  each  issuance  of  additional  Common  Stock  or  Convertible
Securities  pursuant to the terms of the agreement relating to such acquisition,
the  consideration  received  shall  be  deemed  to be such  part  of the  total
consideration  as the portion of the dollar  purchase price then and theretofore
paid in Common Stock or Convertible Securities bears to the total maximum dollar
purchase price payable in Common Stock or Convertible Securities multiplied by a
fraction,  the  numerator of which shall be the number of shares (or in the case
of Convertible Securities other than stock, the aggregate principal amount) then
issued and the  denominator  of which shall be the total number of shares (or in
the case of Convertible  Securities  other than stock,  the aggregate  principal
amount) then and theretofore issued under such acquisition  agreement.  If it is
determined that any part of the deferred or contingent  portion of such purchase
price shall not be payable,  the Purchase Price then in effect  hereunder  shall
forthwith be readjusted to such Purchase Price as would have obtained (i) ha the
adjustment made in connection with such  acquisition been made upon the basis of
the  issuance  of only the  number  of shares  of  Common  Stock or  Convertible
Securities  actually  issued in connection with such  acquisition,  and (ii) had
adjustments  been made on the basis of the Purchase  Price as adjusted in clause
(1) for all issued or sale (as prices which would have  affected  such  adjusted
Purchase  Price) of Common Stock or rights,  options or  Convertible  Securities
made after such acquisition. In the event that only a part of the purchase price
for an  acquisition  is paid in Common Stock or  Convertible  Securities  in the
manner referred to in this clause (8), the term"total  consideration" as used in
this clause (8) shall mean that part of the aggregate consideration as is fairly
allocable to the purchase price paid in Common Stock or  Convertible  Securities
in the manner  referred to in this clause  (8),  as  determined  by the Board of
Directors of the Company.

     (9)  Notwithstanding  anything  to the  contrary  in this  Section  II., no
adjustment in the Purchase  Price shall result,  pursuant to Subsection A. above
or otherwise,  from the issuance by the Company of shares of its Common Stock as
a result of the following transactions:

     (a) The  exercise of options  heretofore  or  hereafter  granted  under the
Company's 1986 Incentive Stock Option Plan, as the same may be amended, extended
or substituted  from time to time provided,  that the number of shares available
thereunder   may  not  be  increased  by  any  such   amendment,   extension  or
substitution; and

     (b) The  exercise of options  heretofore  or  hereafter  granted  under the
Company's  1993 Stock  Option  Plan,  as the same may be  amended,  extended  or
substituted  from time to time  provided,  that the  number of shares  available
thereunder   may  not  be  increased  by  any  such   amendment,   extension  or
substitution.

     C. In case the  Company  shall  declare a dividend  upon the  Common  Stock
payable  otherwise  than out of  consolidated  earnings or  consolidated  earned
surplus, determined in accordance with generally accepted accounting principles,
including the making of appropriate deductions for minority interest, if any, in
subsidiary  corporations,  and  otherwise  than in Common  Stock or  Convertible
Securities,  the Company shall give the holders of each Warrant thirty (30) days
prior  written  notice of the date as of which the  holders  of Common  Stock of
record entitled to such special  dividend shall be determined.  For the purposes
of the foregoing a dividend  other than in cash shall be considered  payable out
of earnings or surplus (other than  revaluation or paid-in  surplus) only to the
extent that such  earnings  or surplus  are charged an amount  equal to the fair
value of such dividend as determined by the Board of Directors of the Company.

     D. (1) In case the  Company  shall at any time  subdivide  its  outstanding
shares of Common Stock into a greater  number of shares,  the Purchase  Price in
effect immediately prior to such subdivision shall be  proportionately  reduced,
and,  conversely  (2) in case the  outstanding  shares  of  Common  Stock of the
Company shall be combined into a smaller number of shares, the Purchase Price in
effect immediately prior to such combination shall be proportionately increased.

     E. In case of any capital  reorganization  or any  reclassification  of the
Common Stock of the Company,  the consolidation of Company with or the merger of
Company with or into any other  corporation,  or the sale of the  properties and
assets of Company as, or substantially as, an entirety to any other corporation,
then each  holder of a Warrant  then  outstanding  shall be entitled to purchase
such number of shares of stock or other securities or property of Company or any
other  corporation   resulting  from  such   reorganization,   reclassification,
consolidation,  merger,  or sale,  as was  exchanged for the number of shares of
Common Stock of Company  which the holder  would have been  entitled to purchase
except for such action. The subdivision or combination of shares of Common Stock
at any time  outstanding  into a greater  or  lesser  number of shares of Common
Stock  shall not be  deemed  to be a  reclassification  of the  Common  Stock of
Company for the purposes of this Subsection"E."

     F. (1) Except as provided in Subsection G, to follow,  upon each adjustment
of the  Purchase  Price as a result of (a) an issuance  or sale of Common  Stock
below the Purchase  Price as provided in  Subsections  A and B above,  including
(without  limitation) a dividend or  distribution in shares of capital stock, or
(b) a  subdivision  of  outstanding  shares  of  Common  Stock  as  provided  in
Subsection "D.(1)" hereof, the number of shares of Common Stock purchasable upon
exercise of any Warrant  Certificate  shall be increased to the number of shares
of Common Stock  (calculated to the nearest  hundredth)  obtained by multiplying
(i) the number of shares of Common Stock  purchasable  immediately prior to such
adjustment upon exercise of Warrants  (evidenced by the Warrant Certificate held
by such holder) by (ii) the Purchase Price in effect  immediately  prior to such
adjustment, and dividing the product so obtained by the Purchase Price in effect
after such adjustment.

     (2) Except as provided in Subsection "G" to follow, upon each adjustment of
the Purchase  Price as a result of a combination of the Common Stock as provided
in Subsection  "D.(2)" hereof,  the number of shares of Common Stock purchasable
upon  exercise of any Warrant  Certificate  shall be  decreased to the number of
shares of  Common  Stock  (calculated  to the  nearest  hundredth)  obtained  by
multiplying  (a) the number of shares of Common  Stock  purchasable  immediately
prior to such  adjustment  upon  exercise of Warrants  evidenced  by the Warrant
Certificate held by such holder, by (b) the Purchase Price in effect immediately
prior to such  adjustment,  and then  dividing  the  product so  obtained by the
Purchase Price in effect after such adjustment.

     G. In lieu of an adjustment  in the number of shares  covered by a Warrant,
Company may elect, on or after the date of any adjustment of the Purchase Price,
to adjust the number of Warrants.

     H.  Irrespective  of any adjustments or change in the Purchase Price or the
number of shares of the Common Stock issuable upon the exercise of the Warrants,
the Warrant  Certificates  theretofore  and  thereafter  issued may  continue to
express  the  Purchase  Price  per share and the  number  of shares  which  were
expressed upon the Warrant Certificates when initially issued.

     I. Before  taking any action which would cause an  adjustment  reducing the
Purchase  Price below the then par value,  if any, of the shares of Common Stock
issuable upon exercise of the Warrants,  Company shall take any corporate action
which may, in the opinion of its counsel, be necessary in order that Company may
validly and legally  issue  fully paid and  nonassessable  shares of such Common
Stock at such adjusted Purchase Price.

     J.  Whenever  the  Purchase  Price,  the  number of shares of Common  Stock
issuable  upon the  exercise  of each  Warrant,  or the number of  Warrants  are
adjusted as provided in this  Section  II.,  Company  shall  promptly  prepare a
certificate  setting  forth the  Purchase  Price as so  adjusted,  the number of
shares  of  Common  Stock  issuable  upon the  exercise  of each  Warrant  as so
adjusted, and a brief statement of the facts accounting for such adjustment.

     K. If any event occurs as to which in the opinion of the Board of Directors
of the  Company  the other  provisions  of this  Section  II.  are not  strictly
applicable or if strictly  applicable  would not fairly  protect the  conversion
rights of the holders of the Warrants in accordance  with the  essential  intent
and  principles of such  provisions,  then the Board of Directors  shall make an
adjustment  in the  application  of such  provisions,  in  accordance  with such
essential  intent and  principles,  so as to  protect  such  exercise  rights as
aforesaid. III. A. This Certificate, with or without other Warrant Certificates,
upon  surrender at the  principal  office of the Company,  may be exchanged  for
another Warrant  Certificate or Warrant  Certificates  of like tenor  evidencing
Warrants  entitling the holder to purchase a like aggregate  number of Shares as
the  Warrants  evidenced  by the  Warrant  Certificate  or Warrant  Certificates
surrendered.  If only a part of the Warrants  evidenced by this  Certificate are
exercised,  the holder  hereof  shall be  entitled to  receive,  upon  surrender
hereof,  another Warrant  Certificate or Warrant  Certificates for the number of
whole Warrants not exercised.

     B. Upon receipt by Company of evidence reasonably satisfactory to it of the
loss, theft, destruction,  or mutilation of a Warrant Certificate,  and, in case
of loss, theft, destruction,  or mutilation, of indemnity or security reasonably
satisfactory  to it, and  reimbursement  to Company of all  reasonable  expenses
incidental  thereto,  and upon surrender to the Company and  cancellation of the
Warrant Certificate,  if mutilated,  the Company shall deliver to the registered
owner a new Warrant Certificate in lieu of, and evidencing the right to purchase
the same  number  of  shares  as,  the  Warrant  Certificate  so  lost,  stolen,
destroyed, or mutilated.

     C. No  holder  of the  Warrants  evidenced  by this  Certificate  shall  be
entitled to vote or receive  dividends  or be deemed the holder of Shares or any
other securities of Company which may at any time be issuable on the exercise of
these  Warrants for any  purpose,  nor shall  anything  contained in the Warrant
Agreement or herein be construed to confer upon the holder of these Warrants, as
such, any of the rights of a shareholder of Company or any right to vote for the
election  of  directors  or upon any matter  submitted  to  shareholders  at any
meeting thereof, or to give or withhold consent to any corporate action (whether
upon any recapitalization,  issue of stock, reclassification of stock, change of
par value, consolidation, merger, conveyance, or otherwise) or to receive notice
of meetings, or to receive dividends or subscription rights or otherwise,  until
the Warrants  evidenced by this Warrant  Certificate have been exercised and the
Common Stock purchasable upon the exercise thereof has become deliverable.

     D. To the extent that any Warrant  Certificates  remain outstanding at 5:01
P.M.  central  standard time on the Expiration  Date, such  outstanding  Warrant
Certificates  shall be  automatically  deemed exercised on behalf of each record
holder of Warrant  Certificates into shares of the Company's Common Stock at the
rate ("Conversion Rate") of one-tenth (1/10) of a share of Common Stock for each
Warrant  Certificate  or  Certificates  representing,   immediately  before  the
Expiration Date, the right to purchase one share of Common Stock.

     E.  Upon  the  exercise  of the  Warrant,  in lieu of the  issuance  of any
fractional  Shares,  the Company shall pay cash to the registered  holder of the
Warrant based on the  difference  between the market price of the Shares,  which
price  shall be  computed  as the per Share  closing  price (if such  Shares are
listed on an exchange) or the average between the per Share bid and asked prices
as of the close of business  on the  exercise  date as reported by the  National
Association of Securities  Dealers  Automated  Quotation System and the Purchase
Price on the exercise date times the  fractional  Share which is  represented by
the Warrants on the exercise date.  However, if no market price exists, then the
amount of cash to be paid to the registered holder of the Warrant in lieu of any
fractional  Shares shall be the product of the difference  between the per share
Tangible  Net Book Value  (defined  hereafter)  of the  shares of the  Company's
Common Stock outstanding on the last business day prior to the exercise date and
the Purchase  Price on the exercise  date times the  fractional  security  which
otherwise  would  have been  issuable  in the  absence  of this  provision.  For
purposes of payment of cash in lieu of the  issuance of  fractional  securities,
the  term"Tangible  Net Book Value" means the consolidated  total  shareholders'
equity,  determined in accordance with generally accepted accounting  principles
("GAAP"), less the aggregate net amount of the following items to the extent, if
any,  that  they  were  included  in   consolidated   assets  or  deducted  from
consolidated liabilities in computing shareholders' equity:

     (i) all franchises,  licenses,  patents,  patent applications,  copyrights,
trademarks,  trade names,  goodwill,  experimental  or  organizational  expense,
unamortized debt discount and expense, and all other assets which under GAAP are
deemed intangible; and,

     (ii) any write-up of assets after December 31, 1998.

          F. The holder  hereof,  by  accepting  same,  consents and agrees with
Company and with every other holder of a Warrant Certificate that:

     (1) The Warrants evidenced by this Certificate are transferable only on the
registry  books  of the  Company  upon  surrender  of  this  Certificate  at the
principal office of the Company and only as provided below;

     (2)  Company  and may  deem  and  treat  the  person  in  whose  name  this
Certificate  is  registered  as the absolute  owner  thereof and of the Warrants
evidenced thereby  (notwithstanding any notations of ownership or writing on the
Certificate made by anyone other than Company) for all purposes whatsoever,  and
the Company shall not be affected by any notice to the contrary; and

     (3) Company may modify the terms of the Warrant from time to time.

     G. The  registered  holder of any Warrant  Certificate  may  exercise it in
whole or in part at any time,  but only in such  multiples  as are  required  to
permit the  issuance  by  Company of one or more  shares,  by  surrender  of the
Warrant  Certificate  with the form of election to purchase on the reverse  side
thereof duly executed,  to the Company at the principal office of the Company at
or prior to 5:00 P.M. central standard time on July 31, 2009, or such later date
or dates as Company may determine  together with payment of the Purchase  Price,
payable to Company, for each share into which the Warrants are exercised.

     H. Upon  receipt of a Warrant  Certificate,  with the form of  election  to
purchase duly  executed,  accompanied  by payment of the Purchase  Price for its
shares to be  purchased  and an amount equal to any  applicable  transfer tax in
cash,  or by  certified  check,  bank  draft,  or postal or express  money order
payable  to the  order  of  Company,  the  Company  shall  thereupon  cause  the
certificates  for the number of whole  shares to be purchased to be delivered to
or  upon  the  order  of the  registered  holder  of  such  Warrant  Certificate
registered in such name or names as may be designated by such holder.

     I. In case the registered holder of any Warrant Certificate  exercises less
than all the Warrants evidenced thereby,  a new Warrant  Certificate  evidencing
Warrants  equivalent to the Warrants  remaining  unexercised  shall be issued by
Warrant Agent to the  registered  holder of such Warrant  Certificate or to such
holder's duly authorized assigns.

          J. Each  person in whose  name any  certificate  for  shares of Common
Stock of the  Company is issued  upon the  exercise  of  Warrants  shall for all
purposes  be deemed to have  become the holder of record of the shares of Common
Stock represented thereby on, and such certificate shall be dated, the date upon
which the Warrant Certificate  evidencing such Warrants was duly surrendered and
payment of the  Purchase  Price (and any  applicable  transfer  taxes) was made;
provided, however, that if the date of such surrender and payment is a date upon
which the transfer  books of Company are closed,  such person shall be deemed to
have become the record holder of such shares on, and such  certificate  shall be
dated,  the next succeeding  business day on which the transfer books of Company
are open. Prior to the exercise of the Warrants evidenced thereby, the holder of
a Warrant  Certificate  shall not be entitled to any rights of a shareholder  of
Company  with  respect  to  shares  for  which  the  Warrants  are  exercisable,
including,  without limitation, the right to vote, to receive dividends or other
distributions,  or to exercise any preemptive  rights, and shall not be entitled
to receive any notice of any proceedings of Company, except as provided herein.

          WITNESS the facsimile signatures of the proper officers of Company and
its corporate seal. Dated as of July 30, 1999.

                              TGC INDUSTRIES, INC.



                              By:  /s/ Wayne A. Whitener
                                   ____________________________
                                   Wayne A. Whitener, President

ATTEST:

By:    /s/ Kenneth W. Uselton
       _______________________________
         Kenneth W. Uselton,
         Assistant Secretary
<PAGE>




                                  ASSIGNMENT

                  (To be executed by the registered holder if such
                holder desires to transfer the Warrant Certificate)

     FOR  VALUE  RECEIVED  _____________________________________  hereby  sells,
assigns, and transfers unto ______________________

     (Please print name and address of transferee)

- ------------------------------------------------------------------
this Warrant Certificate,  together with all right, title, and interest therein,
and does hereby irrevocably  constitute and appoint  ___________________________
Attorney,  to  transfer  the  within  Warrant  Certificate  on the  books of the
within-named Company, with full power of substitution.

Dated: ________________________ , 19____.

                                        -------------------------
                                                       Signature

                                        -------------------------
                                            Signature Guaranteed

     NOTICE:  The  signature(s)  to this  assignment  must  correspond  with the
name(s) as written upon the face of the Certificate in every particular  without
alteration  or  enlargement  or  any  change  whatever.   Signature(s)  must  be
guaranteed  by a  commercial  bank or trust  company or a member firm of a major
stock exchange.





<PAGE>




     ELECTION TO PURCHASE

     (To be executed if holder desires
     to exercise the Warrant Certificate)
     To: TGC INDUSTRIES, INC.

          The undersigned hereby irrevocably elects to exercise ________________
Warrants  represented  by this  Warrant  Certificate  to purchase  the shares of
Common  Stock  issuable  upon the exercise of such  Warrants  and requests  that
certificates for such shares be issued in the name of:

- ------------------------------------------------------------------
     (Please insert social security or other identifying number)

- ------------------------------------------------------------------
     (Please print name and address)

          If such number of Warrants  does not  constitute  all of the  Warrants
evidenced by this Warrant Certificate, a new Warrant Certificate for the balance
remaining of such Warrants shall be registered in the name of and delivered to:

- ------------------------------------------------------------------
     (Please insert social security or other identifying number)

- ------------------------------------------------------------------

Dated: ____________________, 19_________

                                        -------------------------
                                                       Signature

                                        -------------------------
                                             Signature Guaranteed

     NOTICE:  The signature on this Form of Election to Purchase must correspond
with the name(s) as written upon the face of the Certificate  without alteration
or  enlargement  or any change  whatever.  Signature(s)  must be guaranteed by a
commercial bank or trust company or a member firm of a major stock exchange.





<PAGE>




No. WT 3                                                     200,000 Warrants


                         VOID  AFTER  JULY  31,  2009
                   (unless extended by TGC Industries, Inc.)

                            TGC INDUSTRIES, INC.

                           Warrant Agreement and
                            Warrant Certificate

     I. A. THIS CERTIFIES THAT for value received J M S Inc. Cust FBO Herbert M.
Gardner  Keogh,  or registered  assigns,  is the owner of the number of Warrants
("Warrants") of TGC Industries,  Inc.  (the"Company")  set forth above,  each of
which  entitles  the  owner  hereof to  purchase,  subject  to the  restrictions
referenced  herein,  prior to the close of  business on July 31,  2009,  or such
later date or dates as Company  may  determine  (the"Expiration  Date"),  at the
principal  office  of  the  Company,  one  (1)  share  of  Common  Stock  of TGC
Industries,  Inc.  (the"Shares"),  at the purchase price of $.30 per whole share
(the"Purchase   Price"),   upon  presentation  and  surrender  of  this  Warrant
Certificate  with the Form of Election to Purchase duly executed.  The number of
Warrants  evidenced by this Warrant  Certificate (and the number of Shares which
may be purchased upon exercise  thereof) set forth above is the number as of the
date of this Certificate,  based on the shares of Common Stock of the Company as
constituted at such date.

     B. No Warrant is exercisable by a holder unless, at the time of an exercise
by such  holder,  there is either (1) a  registration  statement  or  prospectus
covering  the Shares that is  effective  under the  Securities  Act of 1933,  as
amended,  and the securities  laws of the state of the address of record of such
holder;  or (2) an exemption  from  registration  is  available  for the Warrant
exercise  and the  issuance  of the Shares in the  opinion of counsel to Company
(and the holder  represents  in writing  that the Shares are being  acquired for
investment  and will not be  distributed  in violation of applicable  securities
laws).

          C. Except as hereafter  provided,] Company shall have no obligation to
register  either  the  Warrants  or the  Shares  into  which  the  Warrants  are
exercisable.

     (1) The Company  agrees  that,  upon  written  request  from the holders of
fifty-one percent (51%) of the then outstanding Warrants (including this Warrant
to the extent then outstanding),  it will take the following action with respect
to a public offering of the Shares,  considering the proposed  effective date of
such  offering,  subject to its ability to use currently  available  audited and
interim  financial   statements  without  having  to  have  any  such  financial
statements specially prepared for such offering:

     (a) promptly  cause to be prepared  and filed under the Act a  registration
statement and related  prospectus  relating to the public offering of the Shares
as may be required  for the lawful  public  offering  thereof in the manner then
contemplated;

     (b) use its best efforts, through its officers and directors, auditors, and
counsel in all matters  necessary or advisable to cause such to become effective
at the earliest possible date after the filing thereof;

     (c) deliver to the holder of this Warrant (to the extent then  outstanding)
such number of copies of such  prospectuses in preliminary and definitive  form,
and amendments thereto,  as it, he, or she may reasonably  require,  and Company
hereby  consents to the use of such  prospectuses  and amendments for the public
offering and sale of the Shares;

     (d) qualify the Shares for sale under applicable Blue Sky laws and continue
such qualification in effect so long as required for the purposes of the sale of
the Shares; and

     (e) pay all fees,  taxes,  and expenses  incident to the performance of its
obligations hereunder (except that each owner of such Shares will be responsible
for  payment of such  owner's own  attorneys'  fees,  Share  sales  commissions,
transfer taxes, and other expenses personal to such owner).

     (2) Following the (one time)  registration  of Shares upon written  request
from the holders of 51% of the then outstanding  Warrants as provided above, any
of the holders of the  remaining  Warrants may request the  registration  of the
remaining  Shares  issuable  upon the  exercise  thereof  (subject to  Company's
ability to use  currently  available  audited and interim  financial  statements
without having to have any such financial statements specially prepared for such
offering),  and Company  shall (at  Company's  own expense)  take the  necessary
action to register such Shares.

     (3) Whenever  Company,  at any time prior to the expiration of this Warrant
as herein  provided,  proposes to file with the Commission for the  registration
under the Act of any of its securities for Company's own benefit, Company shall,
at least thirty days prior to such filing, given written notice of such proposed
filing to the holder of this  Warrant at the last known  address of such holder,
and  shall  offer to  include  in such  filing  for  registration  any  proposed
disposition  of Shares  deliverable  upon the  exercise of the then  outstanding
Warrants,  upon  receipt  by  Company,  not less than  twenty  days prior to the
proposed  filing date, of a written request setting forth the facts with respect
to such proposed disposition.  If such request is made, Company will take action
(at  Company's  own expense) to register  such Shares by including  them in such
filing,  and will take such other  action as may be  requested by such holder to
qualify the Shares for sale under applicable Blue Sky laws.

     ----------------------

     THE  SECURITIES  REPRESENTED  BY THIS  CERTIFICATE  HAVE BEEN  ACQUIRED FOR
INVESTMENT ONLY AND HAVE NOT BEEN  REGISTERED  UNDER THE SECURITIES ACT OF 1933,
AS AMENDED, OR THE SECURITIES LAWS OF ANY STATE. WITHOUT SUCH REGISTRATION, SUCH
SECURITIES  MAY NOT BE SOLD OR  OTHERWISE  TRANSFERRED  AT ANY TIME  WHATSOEVER,
EXCEPT UPON DELIVERY TO THE CORPORATION OF AN OPINION OF COUNSEL SATISFACTORY TO
THE CORPORATION THAT REGISTRATION IS NOT REQUIRED FOR SUCH TRANSFER.

     II. The Purchase  Price,  the number of Shares which may be purchased  upon
the exercise of the Warrants  evidenced by this  Certificate,  and the number of
Warrants  outstanding  are subject to  modification  and adjustment from time to
time upon the occurrence of the events enumerated below:

     A. If and whenever the Company shall issue or sell any shares of its Common
Stock for a  consideration  per share  less  than the  Purchase  Price in effect
immediately  prior to the time of such issue or sale, then,  forthwith upon such
issue or sale, the Purchase Price shall be reduced to a price (calculated to the
nearest one  hundredth of a cent)  determined by dividing (1) an amount equal to
the sum of (a) the  number of shares of  Common  Stock  outstanding  immediately
prior to such issue or sale multiplied by the then existing  Purchase Price, and
(b) the consideration,  if any, received by the Company upon such issue or sale,
by (2) the total number of shares of Common Stock outstanding  immediately after
such issue or sale.

     B. For purposes of Subsection A. above,  the following  clauses (1) to (9),
inclusive, shall also be applicable:

               (1) In case at any time the Company shall grant (whether directly
or by  assumption  in a merger or  otherwise)  any rights to subscribe for or to
purchase,  or any  options for the  purchase  of,  Common  Stock or any stock or
securities  convertible into or exchangeable for Common Stock (such  convertible
or exchangeable stock or securities being herein called Convertible  Securities)
whether or not such  rights or options or the right to convert or  exchange  any
such Convertible Securities are immediately exercisable, and the price per share
for which Common  Stock is issuable  upon the exercise of such rights or options
or upon  conversion or exchange of such  Convertible  Securities  (determined by
dividing (a) the total amount,  if any, received or receivable by the Company as
consideration  for the  granting  of such  rights or  options,  plus the minimum
aggregate  amount of  additional  consideration  payable to the Company upon the
exercise of such rights or options,  plus, in the case of such rights or options
which  relate  to  Convertible  Securities,  the  minimum  aggregate  amount  of
additional  consideration,  if  any,  payable  upon  the  issue  or sale of such
Convertible  Securities and upon the conversion or exchange thereof,  by (b) the
total  maximum  number of shares of Common Stock  issuable  upon the exercise of
such  rights  or  options  or  upon  the  conversion  or  exchange  of all  such
Convertible  Securities  issuable  upon the  exercise of such rights or options)
shall be less than the Purchase Price in effect immediately prior to the time of
the granting of such rights or options,  then the total maximum number of shares
of Common  Stock  issuable  upon the  exercise of such rights or options or upon
conversion  or  exchange  of  the  total  maximum  amount  of  such  Convertible
Securities issuable upon the exercise of such rights or options shall (as of the
date of granting of such rights or options) be deemed to be  outstanding  and to
have been  issued  for such price per share.  Except as  provided  in clause (3)
below,  no further  adjustments  of the  Purchase  Price  shall be made upon the
actual  issue  of such  Common  Stock  or of such  Convertible  Securities  upon
exercise of such rights or options or upon the actual issue of such Common Stock
or of such  Convertible  Securities  upon  exercise of such rights or options or
upon the  issue  of such  Common  Stock  upon  conversion  or  exchange  of such
Convertible Securities.

               (2) In case the  Company  shall  issue  (whether  directly  or by
assumption in a merger or otherwise) or sell any Convertible Securities, whether
or not the rights to exchange or convert thereunder are immediately exercisable,
and the price per share for which Common Stock is issuable upon such  conversion
or exchange  (determined by dividing (a) the total amount received or receivable
by the corporation as  consideration  for the issue or sale of such  Convertible
Securities,  plus the minimum aggregate amount of additional  consideration,  if
any, payable to the corporation upon the conversion or exchange thereof,  by (b)
the total maximum  number of shares of Common Stock issuable upon the conversion
or exchange of all such Convertible  Securities) shall be less than the Purchase
Price in effect  immediately  prior to the time of such issue or sale,  then the
total  maximum  number of shares of Common Stock  issuable  upon  conversion  or
exchange of all such  Convertible  Securities shall (as of the date of the issue
or sale of such Convertible  Securities) be deemed to be outstanding and to have
been  issued for such price per share,  provided  that (i) except as provided in
clause (3) below,  no further  adjustments  of the Purchase  Price shall be made
upon the actual issue of such Common Stock upon  conversion  or exchange of such
Convertible  Securities,  and (ii) if any such issue or sale of such Convertible
Securities  is made upon  exercise of any rights to subscribe for or to purchase
or any option to purchase any such Convertible  Securities for which adjustments
of the Purchase  Price have been or are to be made pursuant to other  provisions
of this Subsection B., no further adjustment of the Purchase Price shall be made
by reason of such issue or sale.

               (3) Upon the happening of any of the following events, namely, if
the purchase price  provided in any rights or options  referred to in clause (1)
of this Subsection B., the additional  consideration,  if any,  payable upon the
conversion or exchange of  Convertible  Securities  referred to in clause (1) or
clause  (2) of  this  Subsection  B.,  or the  rate  at  which  any  Convertible
Securities  referred to in clause (1) or clause (2) of this  Subsection  (B) are
convertible into or exchangeable for Common Stock shall change (other than under
or by reason of provisions  designed to protect against dilution),  the Purchase
Price in effect at the time of such event shall  forthwith be  readjusted to the
Purchase  Price  which  would have been in effect at such time had such  rights,
options or Convertible  Securities still  outstanding  provided for such changed
purchase price, additional consideration or conversion rate, as the case may be,
at the time initially granted, issued or sold; and on the expiration of any such
option or right or the termination of any such right to convert or exchange such
Convertible  Securities,  the  Purchase  Price  then in effect  hereunder  shall
forthwith be increased to the Purchase  Price which would have been in effect at
the time of such expiration or termination had such right, option or Convertible
Security,  to the extent  outstanding  immediately  prior to such  expiration or
termination,  never been issued, and the Common Stock issuable  thereunder shall
no longer be deemed to be outstanding. If the purchase price provided for in any
such right or option referred to in clause (1) of this Subsection B. or the rate
at which any Convertible  Securities  referred to in clause (1) or clause (2) of
this Subsection B. are convertible into or exchangeable into or exchangeable for
Common Stock,  shall decrease at any time under or by reason of provisions  with
respect  thereto  designed  to  protect  against  dilution,  then in case of the
delivery of Common  Stock upon the  exercise of any such right or option or upon
conversion or exchange of any such Convertible Security, the Purchase Price then
in effect  hereunder shall  forthwith be adjusted to such  respective  amount as
would have obtained had such rights,  option or Convertible  Security never been
issued as to such Common Stock and had  adjustments  been made upon the issuance
of the shares of Common Stock delivered as aforesaid, but only if as a result of
such  adjustment  the  Purchase  Price  then  in  effect  hereunder  is  thereby
decreased.

     (4) In case  the  Company  shall  declare  a  dividend  or make  any  other
distributions  upon  any  stock  of the  Company  payable  in  Common  Stock  or
Convertible Securities,  any Common Stock or Convertible Securities, as the case
may be, issuable in payment of such dividend or distribution  shall be deemed to
have been issued or sold without consideration.

               (5) In case any shares of Common Stock or Convertible  Securities
or any  rights or options  to  purchase  any such  Common  Stock or  Convertible
Securities shall be issued or sold for cash, the consideration received therefor
shall be deemed to be the  amount  received  by the  Company  therefor,  without
deduction therefrom of any expenses incurred or any underwriting  commissions or
concessions paid or allowed by the Company in connection therewith.  In case any
shares of Common  Stock or  Convertible  Securities  or any rights or options to
purchase any such Common Stock or Convertible Securities shall be issued or sold
for a consideration  other than cash, the amount of the consideration other than
cash  received  by the  Company  shall be  deemed  to be the fair  value of such
consideration  as  determined  in good  faith by the Board of  Directors  of the
Company,  without  deduction  of  any  expenses  incurred  or  any  underwriting
commissions  or  concessions  paid  or  allowed  by the  Company  in  connection
therewith.  In case any shares of Common Stock or Convertible  Securities or any
rights or options to purchase such Common Stock or Convertible  Securities shall
be issued in connection with any merger or consolidation in which the Company is
the surviving corporation,  the amount of consideration therefor shall be deemed
to be the fair value as  determined  by the Board of Directors of the Company of
such  portion of the assets and  business of the  non-surviving  corporation  or
corporations  as such Board shall  determine to be  attributable  to such Common
Stock or Convertible Securities, rights or options, as the case may be.

     (6) In case the  Company  shall take a record of the  holders of its Common
Stock for the  purpose of  entitling  them (a) to  receive a  dividend  or other
distribution  payable in Common Stock or in  Convertible  Securities,  or (b) to
subscribe  for or purchase  Common Stock or  Convertible  Securities,  then such
record date shall be deemed to be the date of the issue or sale of the shares of
Common Stock deemed to have been issued upon the declaration of such dividend or
the making of such other  distribution or the date of the granting of such right
of subscription or purchase, as the case may be.

     (7) The  number of shares of Common  Stock  outstanding  at any given  time
shall not include  shares owned or held or for the account of the  Company,  and
the  disposition  of any such  shares  shall be  considered  an issue or sale of
Common Stock for the purposes of Subsection B.

               (8) Anything in clause (5) of this  Subsection B. to the contrary
notwithstanding, in the case of an acquisition where all or part of the purchase
price is payable in Common Stock or  Convertible  Securities  but is stated as a
dollar amount, where the Company upon making the acquisition pays only part of a
maximum  dollar  purchase  price which is payable in Common Stock or Convertible
Securities  and where the  balance  of such  purchase  price is  deferred  or is
contingently  payable under a formula related to earnings over a period of time,
(a) the  consideration  received for any Common Stock or Convertible  Securities
delivered at the time of the acquisition  shall be deemed to be such part of the
total  consideration  as the portion of the dollar  purchase  price then paid in
Common  Stock or  Convertible  Securities  bears  to the  total  maximum  dollar
purchase price then paid in Common Stock or Convertible  Securities,  and (b) in
connection  with  each  issuance  of  additional  Common  Stock  or  Convertible
Securities  pursuant to the terms of the agreement relating to such acquisition,
the  consideration  received  shall  be  deemed  to be such  part  of the  total
consideration  as the portion of the dollar  purchase price then and theretofore
paid in Common Stock or Convertible Securities bears to the total maximum dollar
purchase price payable in Common Stock or Convertible Securities multiplied by a
fraction,  the  numerator of which shall be the number of shares (or in the case
of Convertible Securities other than stock, the aggregate principal amount) then
issued and the  denominator  of which shall be the total number of shares (or in
the case of Convertible  Securities  other than stock,  the aggregate  principal
amount) then and theretofore issued under such acquisition  agreement.  If it is
determined that any part of the deferred or contingent  portion of such purchase
price shall not be payable,  the Purchase Price then in effect  hereunder  shall
forthwith be readjusted to such Purchase Price as would have obtained (i) ha the
adjustment made in connection with such  acquisition been made upon the basis of
the  issuance  of only the  number  of shares  of  Common  Stock or  Convertible
Securities  actually  issued in connection with such  acquisition,  and (ii) had
adjustments  been made on the basis of the Purchase  Price as adjusted in clause
(1) for all issued or sale (as prices which would have  affected  such  adjusted
Purchase  Price) of Common Stock or rights,  options or  Convertible  Securities
made after such acquisition. In the event that only a part of the purchase price
for an  acquisition  is paid in Common Stock or  Convertible  Securities  in the
manner referred to in this clause (8), the term"total  consideration" as used in
this clause (8) shall mean that part of the aggregate consideration as is fairly
allocable to the purchase price paid in Common Stock or  Convertible  Securities
in the manner  referred to in this clause  (8),  as  determined  by the Board of
Directors of the Company.

     (9)  Notwithstanding  anything  to the  contrary  in this  Section  II., no
adjustment in the Purchase  Price shall result,  pursuant to Subsection A. above
or otherwise,  from the issuance by the Company of shares of its Common Stock as
a result of the following transactions:

     (a) The  exercise of options  heretofore  or  hereafter  granted  under the
Company's 1986 Incentive Stock Option Plan, as the same may be amended, extended
or substituted  from time to time provided,  that the number of shares available
thereunder   may  not  be  increased  by  any  such   amendment,   extension  or
substitution; and

     (b) The  exercise of options  heretofore  or  hereafter  granted  under the
Company's  1993 Stock  Option  Plan,  as the same may be  amended,  extended  or
substituted  from time to time  provided,  that the  number of shares  available
thereunder   may  not  be  increased  by  any  such   amendment,   extension  or
substitution.

     C. In case the  Company  shall  declare a dividend  upon the  Common  Stock
payable  otherwise  than out of  consolidated  earnings or  consolidated  earned
surplus, determined in accordance with generally accepted accounting principles,
including the making of appropriate deductions for minority interest, if any, in
subsidiary  corporations,  and  otherwise  than in Common  Stock or  Convertible
Securities,  the Company shall give the holders of each Warrant thirty (30) days
prior  written  notice of the date as of which the  holders  of Common  Stock of
record entitled to such special  dividend shall be determined.  For the purposes
of the foregoing a dividend  other than in cash shall be considered  payable out
of earnings or surplus (other than  revaluation or paid-in  surplus) only to the
extent that such  earnings  or surplus  are charged an amount  equal to the fair
value of such dividend as determined by the Board of Directors of the Company.

     D. (1) In case the  Company  shall at any time  subdivide  its  outstanding
shares of Common Stock into a greater  number of shares,  the Purchase  Price in
effect immediately prior to such subdivision shall be  proportionately  reduced,
and,  conversely  (2) in case the  outstanding  shares  of  Common  Stock of the
Company shall be combined into a smaller number of shares, the Purchase Price in
effect immediately prior to such combination shall be proportionately increased.

     E. In case of any capital  reorganization  or any  reclassification  of the
Common Stock of the Company,  the consolidation of Company with or the merger of
Company with or into any other  corporation,  or the sale of the  properties and
assets of Company as, or substantially as, an entirety to any other corporation,
then each  holder of a Warrant  then  outstanding  shall be entitled to purchase
such number of shares of stock or other securities or property of Company or any
other  corporation   resulting  from  such   reorganization,   reclassification,
consolidation,  merger,  or sale,  as was  exchanged for the number of shares of
Common Stock of Company  which the holder  would have been  entitled to purchase
except for such action. The subdivision or combination of shares of Common Stock
at any time  outstanding  into a greater  or  lesser  number of shares of Common
Stock  shall not be  deemed  to be a  reclassification  of the  Common  Stock of
Company for the purposes of this Subsection"E."

     F. (1) Except as provided in Subsection G, to follow,  upon each adjustment
of the  Purchase  Price as a result of (a) an issuance  or sale of Common  Stock
below the Purchase  Price as provided in  Subsections  A and B above,  including
(without  limitation) a dividend or  distribution in shares of capital stock, or
(b) a  subdivision  of  outstanding  shares  of  Common  Stock  as  provided  in
Subsection "D.(1)" hereof, the number of shares of Common Stock purchasable upon
exercise of any Warrant  Certificate  shall be increased to the number of shares
of Common Stock  (calculated to the nearest  hundredth)  obtained by multiplying
(i) the number of shares of Common Stock  purchasable  immediately prior to such
adjustment upon exercise of Warrants  (evidenced by the Warrant Certificate held
by such holder) by (ii) the Purchase Price in effect  immediately  prior to such
adjustment, and dividing the product so obtained by the Purchase Price in effect
after such adjustment.

     (2) Except as provided in Subsection "G" to follow, upon each adjustment of
the Purchase  Price as a result of a combination of the Common Stock as provided
in Subsection  "D.(2)" hereof,  the number of shares of Common Stock purchasable
upon  exercise of any Warrant  Certificate  shall be  decreased to the number of
shares of  Common  Stock  (calculated  to the  nearest  hundredth)  obtained  by
multiplying  (a) the number of shares of Common  Stock  purchasable  immediately
prior to such  adjustment  upon  exercise of Warrants  evidenced  by the Warrant
Certificate held by such holder, by (b) the Purchase Price in effect immediately
prior to such  adjustment,  and then  dividing  the  product so  obtained by the
Purchase Price in effect after such adjustment.

     G. In lieu of an adjustment  in the number of shares  covered by a Warrant,
Company may elect, on or after the date of any adjustment of the Purchase Price,
to adjust the number of Warrants.

     H.  Irrespective  of any adjustments or change in the Purchase Price or the
number of shares of the Common Stock issuable upon the exercise of the Warrants,
the Warrant  Certificates  theretofore  and  thereafter  issued may  continue to
express  the  Purchase  Price  per share and the  number  of shares  which  were
expressed upon the Warrant Certificates when initially issued.

     I. Before  taking any action which would cause an  adjustment  reducing the
Purchase  Price below the then par value,  if any, of the shares of Common Stock
issuable upon exercise of the Warrants,  Company shall take any corporate action
which may, in the opinion of its counsel, be necessary in order that Company may
validly and legally  issue  fully paid and  nonassessable  shares of such Common
Stock at such adjusted Purchase Price.

     J.  Whenever  the  Purchase  Price,  the  number of shares of Common  Stock
issuable  upon the  exercise  of each  Warrant,  or the number of  Warrants  are
adjusted as provided in this  Section  II.,  Company  shall  promptly  prepare a
certificate  setting  forth the  Purchase  Price as so  adjusted,  the number of
shares  of  Common  Stock  issuable  upon the  exercise  of each  Warrant  as so
adjusted, and a brief statement of the facts accounting for such adjustment.

     K. If any event occurs as to which in the opinion of the Board of Directors
of the  Company  the other  provisions  of this  Section  II.  are not  strictly
applicable or if strictly  applicable  would not fairly  protect the  conversion
rights of the holders of the Warrants in accordance  with the  essential  intent
and  principles of such  provisions,  then the Board of Directors  shall make an
adjustment  in the  application  of such  provisions,  in  accordance  with such
essential  intent and  principles,  so as to  protect  such  exercise  rights as
aforesaid. III. A. This Certificate, with or without other Warrant Certificates,
upon  surrender at the  principal  office of the Company,  may be exchanged  for
another Warrant  Certificate or Warrant  Certificates  of like tenor  evidencing
Warrants  entitling the holder to purchase a like aggregate  number of Shares as
the  Warrants  evidenced  by the  Warrant  Certificate  or Warrant  Certificates
surrendered.  If only a part of the Warrants  evidenced by this  Certificate are
exercised,  the holder  hereof  shall be  entitled to  receive,  upon  surrender
hereof,  another Warrant  Certificate or Warrant  Certificates for the number of
whole Warrants not exercised.

     B. Upon receipt by Company of evidence reasonably satisfactory to it of the
loss, theft, destruction,  or mutilation of a Warrant Certificate,  and, in case
of loss, theft, destruction,  or mutilation, of indemnity or security reasonably
satisfactory  to it, and  reimbursement  to Company of all  reasonable  expenses
incidental  thereto,  and upon surrender to the Company and  cancellation of the
Warrant Certificate,  if mutilated,  the Company shall deliver to the registered
owner a new Warrant Certificate in lieu of, and evidencing the right to purchase
the same  number  of  shares  as,  the  Warrant  Certificate  so  lost,  stolen,
destroyed, or mutilated.

     C. No  holder  of the  Warrants  evidenced  by this  Certificate  shall  be
entitled to vote or receive  dividends  or be deemed the holder of Shares or any
other securities of Company which may at any time be issuable on the exercise of
these  Warrants for any  purpose,  nor shall  anything  contained in the Warrant
Agreement or herein be construed to confer upon the holder of these Warrants, as
such, any of the rights of a shareholder of Company or any right to vote for the
election  of  directors  or upon any matter  submitted  to  shareholders  at any
meeting thereof, or to give or withhold consent to any corporate action (whether
upon any recapitalization,  issue of stock, reclassification of stock, change of
par value, consolidation, merger, conveyance, or otherwise) or to receive notice
of meetings, or to receive dividends or subscription rights or otherwise,  until
the Warrants  evidenced by this Warrant  Certificate have been exercised and the
Common Stock purchasable upon the exercise thereof has become deliverable.

     D. To the extent that any Warrant  Certificates  remain outstanding at 5:01
P.M.  central  standard time on the Expiration  Date, such  outstanding  Warrant
Certificates  shall be  automatically  deemed exercised on behalf of each record
holder of Warrant  Certificates into shares of the Company's Common Stock at the
rate ("Conversion Rate") of one-tenth (1/10) of a share of Common Stock for each
Warrant  Certificate  or  Certificates  representing,   immediately  before  the
Expiration Date, the right to purchase one share of Common Stock.

     E.  Upon  the  exercise  of the  Warrant,  in lieu of the  issuance  of any
fractional  Shares,  the Company shall pay cash to the registered  holder of the
Warrant based on the  difference  between the market price of the Shares,  which
price  shall be  computed  as the per Share  closing  price (if such  Shares are
listed on an exchange) or the average between the per Share bid and asked prices
as of the close of business  on the  exercise  date as reported by the  National
Association of Securities  Dealers  Automated  Quotation System and the Purchase
Price on the exercise date times the  fractional  Share which is  represented by
the Warrants on the exercise date.  However, if no market price exists, then the
amount of cash to be paid to the registered holder of the Warrant in lieu of any
fractional  Shares shall be the product of the difference  between the per share
Tangible  Net Book Value  (defined  hereafter)  of the  shares of the  Company's
Common Stock outstanding on the last business day prior to the exercise date and
the Purchase  Price on the exercise  date times the  fractional  security  which
otherwise  would  have been  issuable  in the  absence  of this  provision.  For
purposes of payment of cash in lieu of the  issuance of  fractional  securities,
the  term"Tangible  Net Book Value" means the consolidated  total  shareholders'
equity,  determined in accordance with generally accepted accounting  principles
("GAAP"), less the aggregate net amount of the following items to the extent, if
any,  that  they  were  included  in   consolidated   assets  or  deducted  from
consolidated liabilities in computing shareholders' equity:

     (i) all franchises,  licenses,  patents,  patent applications,  copyrights,
trademarks,  trade names,  goodwill,  experimental  or  organizational  expense,
unamortized debt discount and expense, and all other assets which under GAAP are
deemed intangible; and,

               (ii) any write-up of assets after December 31, 1998.

          F. The holder  hereof,  by  accepting  same,  consents and agrees with
Company and with every other holder of a Warrant Certificate that:

     (1) The Warrants evidenced by this Certificate are transferable only on the
registry  books  of the  Company  upon  surrender  of  this  Certificate  at the
principal office of the Company and only as provided below;

     (2)  Company  and may  deem  and  treat  the  person  in  whose  name  this
Certificate  is  registered  as the absolute  owner  thereof and of the Warrants
evidenced thereby  (notwithstanding any notations of ownership or writing on the
Certificate made by anyone other than Company) for all purposes whatsoever,  and
the Company shall not be affected by any notice to the contrary; and

               (3)  Company  may  modify the terms of the  Warrant  from time to
time.

     G. The  registered  holder of any Warrant  Certificate  may  exercise it in
whole or in part at any time,  but only in such  multiples  as are  required  to
permit the  issuance  by  Company of one or more  shares,  by  surrender  of the
Warrant  Certificate  with the form of election to purchase on the reverse  side
thereof duly executed,  to the Company at the principal office of the Company at
or prior to 5:00 P.M. central standard time on July 31, 2009, or such later date
or dates as Company may determine  together with payment of the Purchase  Price,
payable to Company, for each share into which the Warrants are exercised.

     H. Upon  receipt of a Warrant  Certificate,  with the form of  election  to
purchase duly  executed,  accompanied  by payment of the Purchase  Price for its
shares to be  purchased  and an amount equal to any  applicable  transfer tax in
cash,  or by  certified  check,  bank  draft,  or postal or express  money order
payable  to the  order  of  Company,  the  Company  shall  thereupon  cause  the
certificates  for the number of whole  shares to be purchased to be delivered to
or  upon  the  order  of the  registered  holder  of  such  Warrant  Certificate
registered in such name or names as may be designated by such holder.

     I. In case the registered holder of any Warrant Certificate  exercises less
than all the Warrants evidenced thereby,  a new Warrant  Certificate  evidencing
Warrants  equivalent to the Warrants  remaining  unexercised  shall be issued by
Warrant Agent to the  registered  holder of such Warrant  Certificate or to such
holder's duly authorized assigns.

     J. Each person in whose name any  certificate for shares of Common Stock of
the Company is issued upon the  exercise of Warrants  shall for all  purposes be
deemed  to have  become  the  holder of  record  of the  shares of Common  Stock
represented thereby on, and such certificate shall be dated, the date upon which
the Warrant  Certificate  evidencing  such  Warrants  was duly  surrendered  and
payment of the  Purchase  Price (and any  applicable  transfer  taxes) was made;
provided, however, that if the date of such surrender and payment is a date upon
which the transfer  books of Company are closed,  such person shall be deemed to
have become the record holder of such shares on, and such  certificate  shall be
dated,  the next succeeding  business day on which the transfer books of Company
are open. Prior to the exercise of the Warrants evidenced thereby, the holder of
a Warrant  Certificate  shall not be entitled to any rights of a shareholder  of
Company  with  respect  to  shares  for  which  the  Warrants  are  exercisable,
including,  without limitation, the right to vote, to receive dividends or other
distributions,  or to exercise any preemptive  rights, and shall not be entitled
to receive any notice of any proceedings of Company, except as provided herein.

          WITNESS the facsimile signatures of the proper officers of Company and
its corporate seal. Dated as of July 30, 1999.

                              TGC INDUSTRIES, INC.


                              By:  /s/ Wayne A. Whitener
                                   ____________________________
                                   Wayne A. Whitener, President


ATTEST:


By:    /s/ Kenneth W. Uselton
     _________________________
          Kenneth W. Uselton,
         Assistant Secretary


<PAGE>




                                  ASSIGNMENT

                  (To be executed by the registered holder if such
                 holder desires to transfer the Warrant Certificate)

     FOR  VALUE  RECEIVED  _____________________________________  hereby  sells,
assigns, and transfers unto ______________________

     (Please print name and address of transferee)

- ------------------------------------------------------------------
this Warrant Certificate,  together with all right, title, and interest therein,
and does hereby irrevocably  constitute and appoint  ___________________________
Attorney,  to  transfer  the  within  Warrant  Certificate  on the  books of the
within-named Company, with full power of substitution.

Dated: ________________________ , 19____.

                                        -------------------------
                                                       Signature

                                        -------------------------
                                             Signature Guaranteed

     NOTICE:  The  signature(s)  to this  assignment  must  correspond  with the
name(s) as written upon the face of the Certificate in every particular  without
alteration  or  enlargement  or  any  change  whatever.   Signature(s)  must  be
guaranteed  by a  commercial  bank or trust  company or a member firm of a major
stock exchange.





<PAGE>




     ELECTION TO PURCHASE

     (To be executed if holder desires
     to exercise the Warrant Certificate)
     To: TGC INDUSTRIES, INC.

          The undersigned hereby irrevocably elects to exercise ________________
Warrants  represented  by this  Warrant  Certificate  to purchase  the shares of
Common  Stock  issuable  upon the exercise of such  Warrants  and requests  that
certificates for such shares be issued in the name of:

- ------------------------------------------------------------------
     (Please insert social security or other identifying number)

- ------------------------------------------------------------------
     (Please print name and address)

          If such number of Warrants  does not  constitute  all of the  Warrants
evidenced by this Warrant Certificate, a new Warrant Certificate for the balance
remaining of such Warrants shall be registered in the name of and delivered to:

- ------------------------------------------------------------------
     (Please insert social security or other identifying number)

- ------------------------------------------------------------------

Dated: ____________________, 19_________

                                        -------------------------
                                                       Signature

                                        -------------------------
                                             Signature Guaranteed

     NOTICE:  The signature on this Form of Election to Purchase must correspond
with the name(s) as written upon the face of the Certificate  without alteration
or  enlargement  or any change  whatever.  Signature(s)  must be guaranteed by a
commercial bank or trust company or a member firm of a major stock exchange.






<PAGE>




No. WT 4                                                    200,000 Warrants


                             VOID AFTER JULY 31,  2009
                    (unless extended by TGC Industries, Inc.)

                               TGC INDUSTRIES, INC.

                              Warrant Agreement and
                               Warrant Certificate

     I. A.  THIS  CERTIFIES  THAT  for  value  received  Allen  T.  McInnes,  or
registered assigns,  is the owner of the number of Warrants  ("Warrants") of TGC
Industries,  Inc.  (the"Company")  set forth above,  each of which  entitles the
owner hereof to purchase,  subject to the restrictions  referenced herein, prior
to the  close of  business  on July 31,  2009,  or such  later  date or dates as
Company may determine  (the"Expiration  Date"),  at the principal  office of the
Company, one (1) share of Common Stock of TGC Industries, Inc. (the"Shares"), at
the  purchase  price  of  $.30  per  whole  share  (the"Purchase  Price"),  upon
presentation and surrender of this Warrant Certificate with the Form of Election
to Purchase  duly  executed.  The number of Warrants  evidenced  by this Warrant
Certificate  (and the  number of Shares  which may be  purchased  upon  exercise
thereof) set forth above is the number as of the date of this Certificate, based
on the shares of Common Stock of the Company as constituted at such date.

     B. No Warrant is exercisable by a holder unless, at the time of an exercise
by such  holder,  there is either (1) a  registration  statement  or  prospectus
covering  the Shares that is  effective  under the  Securities  Act of 1933,  as
amended,  and the securities  laws of the state of the address of record of such
holder;  or (2) an exemption  from  registration  is  available  for the Warrant
exercise  and the  issuance  of the Shares in the  opinion of counsel to Company
(and the holder  represents  in writing  that the Shares are being  acquired for
investment  and will not be  distributed  in violation of applicable  securities
laws).

          C. Except as hereafter  provided,] Company shall have no obligation to
register  either  the  Warrants  or the  Shares  into  which  the  Warrants  are
exercisable.

     (1) The Company  agrees  that,  upon  written  request  from the holders of
fifty-one percent (51%) of the then outstanding Warrants (including this Warrant
to the extent then outstanding),  it will take the following action with respect
to a public offering of the Shares,  considering the proposed  effective date of
such  offering,  subject to its ability to use currently  available  audited and
interim  financial   statements  without  having  to  have  any  such  financial
statements specially prepared for such offering:

     (a) promptly  cause to be prepared  and filed under the Act a  registration
statement and related  prospectus  relating to the public offering of the Shares
as may be required  for the lawful  public  offering  thereof in the manner then
contemplated;

     (b) use its best efforts, through its officers and directors, auditors, and
counsel in all matters  necessary or advisable to cause such to become effective
at the earliest possible date after the filing thereof;

     (c) deliver to the holder of this Warrant (to the extent then  outstanding)
such number of copies of such  prospectuses in preliminary and definitive  form,
and amendments thereto,  as it, he, or she may reasonably  require,  and Company
hereby  consents to the use of such  prospectuses  and amendments for the public
offering and sale of the Shares;

     (d) qualify the Shares for sale under applicable Blue Sky laws and continue
such qualification in effect so long as required for the purposes of the sale of
the Shares; and

     (e) pay all fees,  taxes,  and expenses  incident to the performance of its
obligations hereunder (except that each owner of such Shares will be responsible
for  payment of such  owner's own  attorneys'  fees,  Share  sales  commissions,
transfer taxes, and other expenses personal to such owner).

     (2) Following the (one time)  registration  of Shares upon written  request
from the holders of 51% of the then outstanding  Warrants as provided above, any
of the holders of the  remaining  Warrants may request the  registration  of the
remaining  Shares  issuable  upon the  exercise  thereof  (subject to  Company's
ability to use  currently  available  audited and interim  financial  statements
without having to have any such financial statements specially prepared for such
offering),  and Company  shall (at  Company's  own expense)  take the  necessary
action to register such Shares.

     (3) Whenever  Company,  at any time prior to the expiration of this Warrant
as herein  provided,  proposes to file with the Commission for the  registration
under the Act of any of its securities for Company's own benefit, Company shall,
at least thirty days prior to such filing, given written notice of such proposed
filing to the holder of this  Warrant at the last known  address of such holder,
and  shall  offer to  include  in such  filing  for  registration  any  proposed
disposition  of Shares  deliverable  upon the  exercise of the then  outstanding
Warrants,  upon  receipt  by  Company,  not less than  twenty  days prior to the
proposed  filing date, of a written request setting forth the facts with respect
to such proposed disposition.  If such request is made, Company will take action
(at  Company's  own expense) to register  such Shares by including  them in such
filing,  and will take such other  action as may be  requested by such holder to
qualify the Shares for sale under applicable Blue Sky laws.

     ----------------------

     THE  SECURITIES  REPRESENTED  BY THIS  CERTIFICATE  HAVE BEEN  ACQUIRED FOR
INVESTMENT ONLY AND HAVE NOT BEEN  REGISTERED  UNDER THE SECURITIES ACT OF 1933,
AS AMENDED, OR THE SECURITIES LAWS OF ANY STATE. WITHOUT SUCH REGISTRATION, SUCH
SECURITIES  MAY NOT BE SOLD OR  OTHERWISE  TRANSFERRED  AT ANY TIME  WHATSOEVER,
EXCEPT UPON DELIVERY TO THE CORPORATION OF AN OPINION OF COUNSEL SATISFACTORY TO
THE CORPORATION THAT REGISTRATION IS NOT REQUIRED FOR SUCH TRANSFER.

     II. The Purchase  Price,  the number of Shares which may be purchased  upon
the exercise of the Warrants  evidenced by this  Certificate,  and the number of
Warrants  outstanding  are subject to  modification  and adjustment from time to
time upon the occurrence of the events enumerated below:

     A. If and whenever the Company shall issue or sell any shares of its Common
Stock for a  consideration  per share  less  than the  Purchase  Price in effect
immediately  prior to the time of such issue or sale, then,  forthwith upon such
issue or sale, the Purchase Price shall be reduced to a price (calculated to the
nearest one  hundredth of a cent)  determined by dividing (1) an amount equal to
the sum of (a) the  number of shares of  Common  Stock  outstanding  immediately
prior to such issue or sale multiplied by the then existing  Purchase Price, and
(b) the consideration,  if any, received by the Company upon such issue or sale,
by (2) the total number of shares of Common Stock outstanding  immediately after
such issue or sale.

     B. For purposes of Subsection A. above,  the following  clauses (1) to (9),
inclusive, shall also be applicable:

               (1) In case at any time the Company shall grant (whether directly
or by  assumption  in a merger or  otherwise)  any rights to subscribe for or to
purchase,  or any  options for the  purchase  of,  Common  Stock or any stock or
securities  convertible into or exchangeable for Common Stock (such  convertible
or exchangeable stock or securities being herein called Convertible  Securities)
whether or not such  rights or options or the right to convert or  exchange  any
such Convertible Securities are immediately exercisable, and the price per share
for which Common  Stock is issuable  upon the exercise of such rights or options
or upon  conversion or exchange of such  Convertible  Securities  (determined by
dividing (a) the total amount,  if any, received or receivable by the Company as
consideration  for the  granting  of such  rights or  options,  plus the minimum
aggregate  amount of  additional  consideration  payable to the Company upon the
exercise of such rights or options,  plus, in the case of such rights or options
which  relate  to  Convertible  Securities,  the  minimum  aggregate  amount  of
additional  consideration,  if  any,  payable  upon  the  issue  or sale of such
Convertible  Securities and upon the conversion or exchange thereof,  by (b) the
total  maximum  number of shares of Common Stock  issuable  upon the exercise of
such  rights  or  options  or  upon  the  conversion  or  exchange  of all  such
Convertible  Securities  issuable  upon the  exercise of such rights or options)
shall be less than the Purchase Price in effect immediately prior to the time of
the granting of such rights or options,  then the total maximum number of shares
of Common  Stock  issuable  upon the  exercise of such rights or options or upon
conversion  or  exchange  of  the  total  maximum  amount  of  such  Convertible
Securities issuable upon the exercise of such rights or options shall (as of the
date of granting of such rights or options) be deemed to be  outstanding  and to
have been  issued  for such price per share.  Except as  provided  in clause (3)
below,  no further  adjustments  of the  Purchase  Price  shall be made upon the
actual  issue  of such  Common  Stock  or of such  Convertible  Securities  upon
exercise of such rights or options or upon the actual issue of such Common Stock
or of such  Convertible  Securities  upon  exercise of such rights or options or
upon the  issue  of such  Common  Stock  upon  conversion  or  exchange  of such
Convertible Securities.

               (2) In case the  Company  shall  issue  (whether  directly  or by
assumption in a merger or otherwise) or sell any Convertible Securities, whether
or not the rights to exchange or convert thereunder are immediately exercisable,
and the price per share for which Common Stock is issuable upon such  conversion
or exchange  (determined by dividing (a) the total amount received or receivable
by the corporation as  consideration  for the issue or sale of such  Convertible
Securities,  plus the minimum aggregate amount of additional  consideration,  if
any, payable to the corporation upon the conversion or exchange thereof,  by (b)
the total maximum  number of shares of Common Stock issuable upon the conversion
or exchange of all such Convertible  Securities) shall be less than the Purchase
Price in effect  immediately  prior to the time of such issue or sale,  then the
total  maximum  number of shares of Common Stock  issuable  upon  conversion  or
exchange of all such  Convertible  Securities shall (as of the date of the issue
or sale of such Convertible  Securities) be deemed to be outstanding and to have
been  issued for such price per share,  provided  that (i) except as provided in
clause (3) below,  no further  adjustments  of the Purchase  Price shall be made
upon the actual issue of such Common Stock upon  conversion  or exchange of such
Convertible  Securities,  and (ii) if any such issue or sale of such Convertible
Securities  is made upon  exercise of any rights to subscribe for or to purchase
or any option to purchase any such Convertible  Securities for which adjustments
of the Purchase  Price have been or are to be made pursuant to other  provisions
of this Subsection B., no further adjustment of the Purchase Price shall be made
by reason of such issue or sale.

               (3) Upon the happening of any of the following events, namely, if
the purchase price  provided in any rights or options  referred to in clause (1)
of this Subsection B., the additional  consideration,  if any,  payable upon the
conversion or exchange of  Convertible  Securities  referred to in clause (1) or
clause  (2) of  this  Subsection  B.,  or the  rate  at  which  any  Convertible
Securities  referred to in clause (1) or clause (2) of this  Subsection  (B) are
convertible into or exchangeable for Common Stock shall change (other than under
or by reason of provisions  designed to protect against dilution),  the Purchase
Price in effect at the time of such event shall  forthwith be  readjusted to the
Purchase  Price  which  would have been in effect at such time had such  rights,
options or Convertible  Securities still  outstanding  provided for such changed
purchase price, additional consideration or conversion rate, as the case may be,
at the time initially granted, issued or sold; and on the expiration of any such
option or right or the termination of any such right to convert or exchange such
Convertible  Securities,  the  Purchase  Price  then in effect  hereunder  shall
forthwith be increased to the Purchase  Price which would have been in effect at
the time of such expiration or termination had such right, option or Convertible
Security,  to the extent  outstanding  immediately  prior to such  expiration or
termination,  never been issued, and the Common Stock issuable  thereunder shall
no longer be deemed to be outstanding. If the purchase price provided for in any
such right or option referred to in clause (1) of this Subsection B. or the rate
at which any Convertible  Securities  referred to in clause (1) or clause (2) of
this Subsection B. are convertible into or exchangeable into or exchangeable for
Common Stock,  shall decrease at any time under or by reason of provisions  with
respect  thereto  designed  to  protect  against  dilution,  then in case of the
delivery of Common  Stock upon the  exercise of any such right or option or upon
conversion or exchange of any such Convertible Security, the Purchase Price then
in effect  hereunder shall  forthwith be adjusted to such  respective  amount as
would have obtained had such rights,  option or Convertible  Security never been
issued as to such Common Stock and had  adjustments  been made upon the issuance
of the shares of Common Stock delivered as aforesaid, but only if as a result of
such  adjustment  the  Purchase  Price  then  in  effect  hereunder  is  thereby
decreased.

     (4) In case  the  Company  shall  declare  a  dividend  or make  any  other
distributions  upon  any  stock  of the  Company  payable  in  Common  Stock  or
Convertible Securities,  any Common Stock or Convertible Securities, as the case
may be, issuable in payment of such dividend or distribution  shall be deemed to
have been issued or sold without consideration.

               (5) In case any shares of Common Stock or Convertible  Securities
or any  rights or options  to  purchase  any such  Common  Stock or  Convertible
Securities shall be issued or sold for cash, the consideration received therefor
shall be deemed to be the  amount  received  by the  Company  therefor,  without
deduction therefrom of any expenses incurred or any underwriting  commissions or
concessions paid or allowed by the Company in connection therewith.  In case any
shares of Common  Stock or  Convertible  Securities  or any rights or options to
purchase any such Common Stock or Convertible Securities shall be issued or sold
for a consideration  other than cash, the amount of the consideration other than
cash  received  by the  Company  shall be  deemed  to be the fair  value of such
consideration  as  determined  in good  faith by the Board of  Directors  of the
Company,  without  deduction  of  any  expenses  incurred  or  any  underwriting
commissions  or  concessions  paid  or  allowed  by the  Company  in  connection
therewith.  In case any shares of Common Stock or Convertible  Securities or any
rights or options to purchase such Common Stock or Convertible  Securities shall
be issued in connection with any merger or consolidation in which the Company is
the surviving corporation,  the amount of consideration therefor shall be deemed
to be the fair value as  determined  by the Board of Directors of the Company of
such  portion of the assets and  business of the  non-surviving  corporation  or
corporations  as such Board shall  determine to be  attributable  to such Common
Stock or Convertible Securities, rights or options, as the case may be.

     (6) In case the  Company  shall take a record of the  holders of its Common
Stock for the  purpose of  entitling  them (a) to  receive a  dividend  or other
distribution  payable in Common Stock or in  Convertible  Securities,  or (b) to
subscribe  for or purchase  Common Stock or  Convertible  Securities,  then such
record date shall be deemed to be the date of the issue or sale of the shares of
Common Stock deemed to have been issued upon the declaration of such dividend or
the making of such other  distribution or the date of the granting of such right
of subscription or purchase, as the case may be.

     (7) The  number of shares of Common  Stock  outstanding  at any given  time
shall not include  shares owned or held or for the account of the  Company,  and
the  disposition  of any such  shares  shall be  considered  an issue or sale of
Common Stock for the purposes of Subsection B.

               (8) Anything in clause (5) of this  Subsection B. to the contrary
notwithstanding, in the case of an acquisition where all or part of the purchase
price is payable in Common Stock or  Convertible  Securities  but is stated as a
dollar amount, where the Company upon making the acquisition pays only part of a
maximum  dollar  purchase  price which is payable in Common Stock or Convertible
Securities  and where the  balance  of such  purchase  price is  deferred  or is
contingently  payable under a formula related to earnings over a period of time,
(a) the  consideration  received for any Common Stock or Convertible  Securities
delivered at the time of the acquisition  shall be deemed to be such part of the
total  consideration  as the portion of the dollar  purchase  price then paid in
Common  Stock or  Convertible  Securities  bears  to the  total  maximum  dollar
purchase price then paid in Common Stock or Convertible  Securities,  and (b) in
connection  with  each  issuance  of  additional  Common  Stock  or  Convertible
Securities  pursuant to the terms of the agreement relating to such acquisition,
the  consideration  received  shall  be  deemed  to be such  part  of the  total
consideration  as the portion of the dollar  purchase price then and theretofore
paid in Common Stock or Convertible Securities bears to the total maximum dollar
purchase price payable in Common Stock or Convertible Securities multiplied by a
fraction,  the  numerator of which shall be the number of shares (or in the case
of Convertible Securities other than stock, the aggregate principal amount) then
issued and the  denominator  of which shall be the total number of shares (or in
the case of Convertible  Securities  other than stock,  the aggregate  principal
amount) then and theretofore issued under such acquisition  agreement.  If it is
determined that any part of the deferred or contingent  portion of such purchase
price shall not be payable,  the Purchase Price then in effect  hereunder  shall
forthwith be readjusted to such Purchase Price as would have obtained (i) ha the
adjustment made in connection with such  acquisition been made upon the basis of
the  issuance  of only the  number  of shares  of  Common  Stock or  Convertible
Securities  actually  issued in connection with such  acquisition,  and (ii) had
adjustments  been made on the basis of the Purchase  Price as adjusted in clause
(1) for all issued or sale (as prices which would have  affected  such  adjusted
Purchase  Price) of Common Stock or rights,  options or  Convertible  Securities
made after such acquisition. In the event that only a part of the purchase price
for an  acquisition  is paid in Common Stock or  Convertible  Securities  in the
manner referred to in this clause (8), the term"total  consideration" as used in
this clause (8) shall mean that part of the aggregate consideration as is fairly
allocable to the purchase price paid in Common Stock or  Convertible  Securities
in the manner  referred to in this clause  (8),  as  determined  by the Board of
Directors of the Company.

     (9)  Notwithstanding  anything  to the  contrary  in this  Section  II., no
adjustment in the Purchase  Price shall result,  pursuant to Subsection A. above
or otherwise,  from the issuance by the Company of shares of its Common Stock as
a result of the following transactions:

     (a) The  exercise of options  heretofore  or  hereafter  granted  under the
Company's 1986 Incentive Stock Option Plan, as the same may be amended, extended
or substituted  from time to time provided,  that the number of shares available
thereunder   may  not  be  increased  by  any  such   amendment,   extension  or
substitution; and

     (b) The  exercise of options  heretofore  or  hereafter  granted  under the
Company's  1993 Stock  Option  Plan,  as the same may be  amended,  extended  or
substituted  from time to time  provided,  that the  number of shares  available
thereunder   may  not  be  increased  by  any  such   amendment,   extension  or
substitution.

     C. In case the  Company  shall  declare a dividend  upon the  Common  Stock
payable  otherwise  than out of  consolidated  earnings or  consolidated  earned
surplus, determined in accordance with generally accepted accounting principles,
including the making of appropriate deductions for minority interest, if any, in
subsidiary  corporations,  and  otherwise  than in Common  Stock or  Convertible
Securities,  the Company shall give the holders of each Warrant thirty (30) days
prior  written  notice of the date as of which the  holders  of Common  Stock of
record entitled to such special  dividend shall be determined.  For the purposes
of the foregoing a dividend  other than in cash shall be considered  payable out
of earnings or surplus (other than  revaluation or paid-in  surplus) only to the
extent that such  earnings  or surplus  are charged an amount  equal to the fair
value of such dividend as determined by the Board of Directors of the Company.

     D. (1) In case the  Company  shall at any time  subdivide  its  outstanding
shares of Common Stock into a greater  number of shares,  the Purchase  Price in
effect immediately prior to such subdivision shall be  proportionately  reduced,
and,  conversely  (2) in case the  outstanding  shares  of  Common  Stock of the
Company shall be combined into a smaller number of shares, the Purchase Price in
effect immediately prior to such combination shall be proportionately increased.

     E. In case of any capital  reorganization  or any  reclassification  of the
Common Stock of the Company,  the consolidation of Company with or the merger of
Company with or into any other  corporation,  or the sale of the  properties and
assets of Company as, or substantially as, an entirety to any other corporation,
then each  holder of a Warrant  then  outstanding  shall be entitled to purchase
such number of shares of stock or other securities or property of Company or any
other  corporation   resulting  from  such   reorganization,   reclassification,
consolidation,  merger,  or sale,  as was  exchanged for the number of shares of
Common Stock of Company  which the holder  would have been  entitled to purchase
except for such action. The subdivision or combination of shares of Common Stock
at any time  outstanding  into a greater  or  lesser  number of shares of Common
Stock  shall not be  deemed  to be a  reclassification  of the  Common  Stock of
Company for the purposes of this Subsection"E."

     F. (1) Except as provided in Subsection G, to follow,  upon each adjustment
of the  Purchase  Price as a result of (a) an issuance  or sale of Common  Stock
below the Purchase  Price as provided in  Subsections  A and B above,  including
(without  limitation) a dividend or  distribution in shares of capital stock, or
(b) a  subdivision  of  outstanding  shares  of  Common  Stock  as  provided  in
Subsection "D.(1)" hereof, the number of shares of Common Stock purchasable upon
exercise of any Warrant  Certificate  shall be increased to the number of shares
of Common Stock  (calculated to the nearest  hundredth)  obtained by multiplying
(i) the number of shares of Common Stock  purchasable  immediately prior to such
adjustment upon exercise of Warrants  (evidenced by the Warrant Certificate held
by such holder) by (ii) the Purchase Price in effect  immediately  prior to such
adjustment, and dividing the product so obtained by the Purchase Price in effect
after such adjustment.

     (2) Except as provided in Subsection "G" to follow, upon each adjustment of
the Purchase  Price as a result of a combination of the Common Stock as provided
in Subsection  "D.(2)" hereof,  the number of shares of Common Stock purchasable
upon  exercise of any Warrant  Certificate  shall be  decreased to the number of
shares of  Common  Stock  (calculated  to the  nearest  hundredth)  obtained  by
multiplying  (a) the number of shares of Common  Stock  purchasable  immediately
prior to such  adjustment  upon  exercise of Warrants  evidenced  by the Warrant
Certificate held by such holder, by (b) the Purchase Price in effect immediately
prior to such  adjustment,  and then  dividing  the  product so  obtained by the
Purchase Price in effect after such adjustment.

     G. In lieu of an adjustment  in the number of shares  covered by a Warrant,
Company may elect, on or after the date of any adjustment of the Purchase Price,
to adjust the number of Warrants.

     H.  Irrespective  of any adjustments or change in the Purchase Price or the
number of shares of the Common Stock issuable upon the exercise of the Warrants,
the Warrant  Certificates  theretofore  and  thereafter  issued may  continue to
express  the  Purchase  Price  per share and the  number  of shares  which  were
expressed upon the Warrant Certificates when initially issued.

     I. Before  taking any action which would cause an  adjustment  reducing the
Purchase  Price below the then par value,  if any, of the shares of Common Stock
issuable upon exercise of the Warrants,  Company shall take any corporate action
which may, in the opinion of its counsel, be necessary in order that Company may
validly and legally  issue  fully paid and  nonassessable  shares of such Common
Stock at such adjusted Purchase Price.

     J.  Whenever  the  Purchase  Price,  the  number of shares of Common  Stock
issuable  upon the  exercise  of each  Warrant,  or the number of  Warrants  are
adjusted as provided in this  Section  II.,  Company  shall  promptly  prepare a
certificate  setting  forth the  Purchase  Price as so  adjusted,  the number of
shares  of  Common  Stock  issuable  upon the  exercise  of each  Warrant  as so
adjusted, and a brief statement of the facts accounting for such adjustment.

     K. If any event occurs as to which in the opinion of the Board of Directors
of the  Company  the other  provisions  of this  Section  II.  are not  strictly
applicable or if strictly  applicable  would not fairly  protect the  conversion
rights of the holders of the Warrants in accordance  with the  essential  intent
and  principles of such  provisions,  then the Board of Directors  shall make an
adjustment  in the  application  of such  provisions,  in  accordance  with such
essential  intent and  principles,  so as to  protect  such  exercise  rights as
aforesaid. III. A. This Certificate, with or without other Warrant Certificates,
upon  surrender at the  principal  office of the Company,  may be exchanged  for
another Warrant  Certificate or Warrant  Certificates  of like tenor  evidencing
Warrants  entitling the holder to purchase a like aggregate  number of Shares as
the  Warrants  evidenced  by the  Warrant  Certificate  or Warrant  Certificates
surrendered.  If only a part of the Warrants  evidenced by this  Certificate are
exercised,  the holder  hereof  shall be  entitled to  receive,  upon  surrender
hereof,  another Warrant  Certificate or Warrant  Certificates for the number of
whole Warrants not exercised.

     B. Upon receipt by Company of evidence reasonably satisfactory to it of the
loss, theft, destruction,  or mutilation of a Warrant Certificate,  and, in case
of loss, theft, destruction,  or mutilation, of indemnity or security reasonably
satisfactory  to it, and  reimbursement  to Company of all  reasonable  expenses
incidental  thereto,  and upon surrender to the Company and  cancellation of the
Warrant Certificate,  if mutilated,  the Company shall deliver to the registered
owner a new Warrant Certificate in lieu of, and evidencing the right to purchase
the same  number  of  shares  as,  the  Warrant  Certificate  so  lost,  stolen,
destroyed, or mutilated.

     C. No  holder  of the  Warrants  evidenced  by this  Certificate  shall  be
entitled to vote or receive  dividends  or be deemed the holder of Shares or any
other securities of Company which may at any time be issuable on the exercise of
these  Warrants for any  purpose,  nor shall  anything  contained in the Warrant
Agreement or herein be construed to confer upon the holder of these Warrants, as
such, any of the rights of a shareholder of Company or any right to vote for the
election  of  directors  or upon any matter  submitted  to  shareholders  at any
meeting thereof, or to give or withhold consent to any corporate action (whether
upon any recapitalization,  issue of stock, reclassification of stock, change of
par value, consolidation, merger, conveyance, or otherwise) or to receive notice
of meetings, or to receive dividends or subscription rights or otherwise,  until
the Warrants  evidenced by this Warrant  Certificate have been exercised and the
Common Stock purchasable upon the exercise thereof has become deliverable.

     D. To the extent that any Warrant  Certificates  remain outstanding at 5:01
P.M.  central  standard time on the Expiration  Date, such  outstanding  Warrant
Certificates  shall be  automatically  deemed exercised on behalf of each record
holder of Warrant  Certificates into shares of the Company's Common Stock at the
rate ("Conversion Rate") of one-tenth (1/10) of a share of Common Stock for each
Warrant  Certificate  or  Certificates  representing,   immediately  before  the
Expiration Date, the right to purchase one share of Common Stock.

     E.  Upon  the  exercise  of the  Warrant,  in lieu of the  issuance  of any
fractional  Shares,  the Company shall pay cash to the registered  holder of the
Warrant based on the  difference  between the market price of the Shares,  which
price  shall be  computed  as the per Share  closing  price (if such  Shares are
listed on an exchange) or the average between the per Share bid and asked prices
as of the close of business  on the  exercise  date as reported by the  National
Association of Securities  Dealers  Automated  Quotation System and the Purchase
Price on the exercise date times the  fractional  Share which is  represented by
the Warrants on the exercise date.  However, if no market price exists, then the
amount of cash to be paid to the registered holder of the Warrant in lieu of any
fractional  Shares shall be the product of the difference  between the per share
Tangible  Net Book Value  (defined  hereafter)  of the  shares of the  Company's
Common Stock outstanding on the last business day prior to the exercise date and
the Purchase  Price on the exercise  date times the  fractional  security  which
otherwise  would  have been  issuable  in the  absence  of this  provision.  For
purposes of payment of cash in lieu of the  issuance of  fractional  securities,
the  term"Tangible  Net Book Value" means the consolidated  total  shareholders'
equity,  determined in accordance with generally accepted accounting  principles
("GAAP"), less the aggregate net amount of the following items to the extent, if
any,  that  they  were  included  in   consolidated   assets  or  deducted  from
consolidated liabilities in computing shareholders' equity:

     (i) all franchises,  licenses,  patents,  patent applications,  copyrights,
trademarks,  trade names,  goodwill,  experimental  or  organizational  expense,
unamortized debt discount and expense, and all other assets which under GAAP are
deemed intangible; and,

               (ii) any write-up of assets after December 31, 1998.

          F. The holder  hereof,  by  accepting  same,  consents and agrees with
Company and with every other holder of a Warrant Certificate that:

     (1) The Warrants evidenced by this Certificate are transferable only on the
registry  books  of the  Company  upon  surrender  of  this  Certificate  at the
principal office of the Company and only as provided below;

     (2)  Company  and may  deem  and  treat  the  person  in  whose  name  this
Certificate  is  registered  as the absolute  owner  thereof and of the Warrants
evidenced thereby  (notwithstanding any notations of ownership or writing on the
Certificate made by anyone other than Company) for all purposes whatsoever,  and
the Company shall not be affected by any notice to the contrary; and

               (3)  Company  may  modify the terms of the  Warrant  from time to
time.

     G. The  registered  holder of any Warrant  Certificate  may  exercise it in
whole or in part at any time,  but only in such  multiples  as are  required  to
permit the  issuance  by  Company of one or more  shares,  by  surrender  of the
Warrant  Certificate  with the form of election to purchase on the reverse  side
thereof duly executed,  to the Company at the principal office of the Company at
or prior to 5:00 P.M. central standard time on July 31, 2009, or such later date
or dates as Company may determine  together with payment of the Purchase  Price,
payable to Company, for each share into which the Warrants are exercised.

     H. Upon  receipt of a Warrant  Certificate,  with the form of  election  to
purchase duly  executed,  accompanied  by payment of the Purchase  Price for its
shares to be  purchased  and an amount equal to any  applicable  transfer tax in
cash,  or by  certified  check,  bank  draft,  or postal or express  money order
payable  to the  order  of  Company,  the  Company  shall  thereupon  cause  the
certificates  for the number of whole  shares to be purchased to be delivered to
or  upon  the  order  of the  registered  holder  of  such  Warrant  Certificate
registered in such name or names as may be designated by such holder.

     I. In case the registered holder of any Warrant Certificate  exercises less
than all the Warrants evidenced thereby,  a new Warrant  Certificate  evidencing
Warrants  equivalent to the Warrants  remaining  unexercised  shall be issued by
Warrant Agent to the  registered  holder of such Warrant  Certificate or to such
holder's duly authorized assigns.

          J. Each  person in whose  name any  certificate  for  shares of Common
Stock of the  Company is issued  upon the  exercise  of  Warrants  shall for all
purposes  be deemed to have  become the holder of record of the shares of Common
Stock represented thereby on, and such certificate shall be dated, the date upon
which the Warrant Certificate  evidencing such Warrants was duly surrendered and
payment of the  Purchase  Price (and any  applicable  transfer  taxes) was made;
provided, however, that if the date of such surrender and payment is a date upon
which the transfer  books of Company are closed,  such person shall be deemed to
have become the record holder of such shares on, and such  certificate  shall be
dated,  the next succeeding  business day on which the transfer books of Company
are open. Prior to the exercise of the Warrants evidenced thereby, the holder of
a Warrant  Certificate  shall not be entitled to any rights of a shareholder  of
Company  with  respect  to  shares  for  which  the  Warrants  are  exercisable,
including,  without limitation, the right to vote, to receive dividends or other
distributions,  or to exercise any preemptive  rights, and shall not be entitled
to receive any notice of any proceedings of Company, except as provided herein.

          WITNESS the facsimile signatures of the proper officers of Company and
its corporate seal. Dated as of July 30, 1999.

                              TGC INDUSTRIES, INC.


                              By:  /s/ Wayne A. Whitener

                                   ____________________________
                                   Wayne A. Whitener, President
ATTEST:


By:    /s/ Kenneth W. Uselton
       ________________________
         Kenneth W. Uselton,
         Assistant Secretary
 <PAGE>




                                 ASSIGNMENT

                (To be executed by the registered holder if such
               holder desires to transfer the Warrant Certificate)

     FOR  VALUE  RECEIVED  _____________________________________  hereby  sells,
assigns, and transfers unto ______________________

     (Please print name and address of transferee)

- ------------------------------------------------------------------
this Warrant Certificate,  together with all right, title, and interest therein,
and does hereby irrevocably  constitute and appoint  ___________________________
Attorney,  to  transfer  the  within  Warrant  Certificate  on the  books of the
within-named Company, with full power of substitution.

Dated: ________________________ , 19____.

                                        -------------------------
                                                       Signature

                                        -------------------------
                                              Signature Guaranteed

     NOTICE:  The  signature(s)  to this  assignment  must  correspond  with the
name(s) as written upon the face of the Certificate in every particular  without
alteration  or  enlargement  or  any  change  whatever.   Signature(s)  must  be
guaranteed  by a  commercial  bank or trust  company or a member firm of a major
stock exchange.





<PAGE>




     ELECTION TO PURCHASE

     (To be executed if holder desires
     to exercise the Warrant Certificate)
     To: TGC INDUSTRIES, INC.

          The undersigned hereby irrevocably elects to exercise ________________
Warrants  represented  by this  Warrant  Certificate  to purchase  the shares of
Common  Stock  issuable  upon the exercise of such  Warrants  and requests  that
certificates for such shares be issued in the name of:

- ------------------------------------------------------------------
     (Please insert social security or other identifying number)

- ------------------------------------------------------------------
     (Please print name and address)

          If such number of Warrants  does not  constitute  all of the  Warrants
evidenced by this Warrant Certificate, a new Warrant Certificate for the balance
remaining of such Warrants shall be registered in the name of and delivered to:

- ------------------------------------------------------------------
     (Please insert social security or other identifying number)

- ------------------------------------------------------------------

Dated: ____________________, 19_________

                                        -------------------------
                                                       Signature

                                        -------------------------
                                             Signature Guaranteed

     NOTICE:  The signature on this Form of Election to Purchase must correspond
with the name(s) as written upon the face of the Certificate  without alteration
or  enlargement  or any change  whatever.  Signature(s)  must be guaranteed by a
commercial bank or trust company or a member firm of a major stock exchange.





<PAGE>




No. WT 5                                                     50,000 Warrants


                            VOID AFTER JULY 31,  2009
                    (unless extended by TGC Industries, Inc.)

                              TGC INDUSTRIES, INC.

                              Warrant Agreement and
                               Warrant Certificate

     I. A.  THIS  CERTIFIES  THAT  for  value  received  Wayne A.  Whitener,  or
registered assigns,  is the owner of the number of Warrants  ("Warrants") of TGC
Industries,  Inc.  (the"Company")  set forth above,  each of which  entitles the
owner hereof to purchase,  subject to the restrictions  referenced herein, prior
to the  close of  business  on July 31,  2009,  or such  later  date or dates as
Company may determine  (the"Expiration  Date"),  at the principal  office of the
Company, one (1) share of Common Stock of TGC Industries, Inc. (the"Shares"), at
the  purchase  price  of  $.30  per  whole  share  (the"Purchase  Price"),  upon
presentation and surrender of this Warrant Certificate with the Form of Election
to Purchase  duly  executed.  The number of Warrants  evidenced  by this Warrant
Certificate  (and the  number of Shares  which may be  purchased  upon  exercise
thereof) set forth above is the number as of the date of this Certificate, based
on the shares of Common Stock of the Company as constituted at such date.

     B. No Warrant is exercisable by a holder unless, at the time of an exercise
by such  holder,  there is either (1) a  registration  statement  or  prospectus
covering  the Shares that is  effective  under the  Securities  Act of 1933,  as
amended,  and the securities  laws of the state of the address of record of such
holder;  or (2) an exemption  from  registration  is  available  for the Warrant
exercise  and the  issuance  of the Shares in the  opinion of counsel to Company
(and the holder  represents  in writing  that the Shares are being  acquired for
investment  and will not be  distributed  in violation of applicable  securities
laws).

          C. Except as hereafter  provided,] Company shall have no obligation to
register  either  the  Warrants  or the  Shares  into  which  the  Warrants  are
exercisable.

     (1) The Company  agrees  that,  upon  written  request  from the holders of
fifty-one percent (51%) of the then outstanding Warrants (including this Warrant
to the extent then outstanding),  it will take the following action with respect
to a public offering of the Shares,  considering the proposed  effective date of
such  offering,  subject to its ability to use currently  available  audited and
interim  financial   statements  without  having  to  have  any  such  financial
statements specially prepared for such offering:

     (a) promptly  cause to be prepared  and filed under the Act a  registration
statement and related  prospectus  relating to the public offering of the Shares
as may be required  for the lawful  public  offering  thereof in the manner then
contemplated;

     (b) use its best efforts, through its officers and directors, auditors, and
counsel in all matters  necessary or advisable to cause such to become effective
at the earliest possible date after the filing thereof;

     (c) deliver to the holder of this Warrant (to the extent then  outstanding)
such number of copies of such  prospectuses in preliminary and definitive  form,
and amendments thereto,  as it, he, or she may reasonably  require,  and Company
hereby  consents to the use of such  prospectuses  and amendments for the public
offering and sale of the Shares;

     (d) qualify the Shares for sale under applicable Blue Sky laws and continue
such qualification in effect so long as required for the purposes of the sale of
the Shares; and

     (e) pay all fees,  taxes,  and expenses  incident to the performance of its
obligations hereunder (except that each owner of such Shares will be responsible
for  payment of such  owner's own  attorneys'  fees,  Share  sales  commissions,
transfer taxes, and other expenses personal to such owner).

     (2) Following the (one time)  registration  of Shares upon written  request
from the holders of 51% of the then outstanding  Warrants as provided above, any
of the holders of the  remaining  Warrants may request the  registration  of the
remaining  Shares  issuable  upon the  exercise  thereof  (subject to  Company's
ability to use  currently  available  audited and interim  financial  statements
without having to have any such financial statements specially prepared for such
offering),  and Company  shall (at  Company's  own expense)  take the  necessary
action to register such Shares.

     (3) Whenever  Company,  at any time prior to the expiration of this Warrant
as herein  provided,  proposes to file with the Commission for the  registration
under the Act of any of its securities for Company's own benefit, Company shall,
at least thirty days prior to such filing, given written notice of such proposed
filing to the holder of this  Warrant at the last known  address of such holder,
and  shall  offer to  include  in such  filing  for  registration  any  proposed
disposition  of Shares  deliverable  upon the  exercise of the then  outstanding
Warrants,  upon  receipt  by  Company,  not less than  twenty  days prior to the
proposed  filing date, of a written request setting forth the facts with respect
to such proposed disposition.  If such request is made, Company will take action
(at  Company's  own expense) to register  such Shares by including  them in such
filing,  and will take such other  action as may be  requested by such holder to
qualify the Shares for sale under applicable Blue Sky laws.

     ----------------------

     THE  SECURITIES  REPRESENTED  BY THIS  CERTIFICATE  HAVE BEEN  ACQUIRED FOR
INVESTMENT ONLY AND HAVE NOT BEEN  REGISTERED  UNDER THE SECURITIES ACT OF 1933,
AS AMENDED, OR THE SECURITIES LAWS OF ANY STATE. WITHOUT SUCH REGISTRATION, SUCH
SECURITIES  MAY NOT BE SOLD OR  OTHERWISE  TRANSFERRED  AT ANY TIME  WHATSOEVER,
EXCEPT UPON DELIVERY TO THE CORPORATION OF AN OPINION OF COUNSEL SATISFACTORY TO
THE CORPORATION THAT REGISTRATION IS NOT REQUIRED FOR SUCH TRANSFER.

     II. The Purchase  Price,  the number of Shares which may be purchased  upon
the exercise of the Warrants  evidenced by this  Certificate,  and the number of
Warrants  outstanding  are subject to  modification  and adjustment from time to
time upon the occurrence of the events enumerated below:

     A. If and whenever the Company shall issue or sell any shares of its Common
Stock for a  consideration  per share  less  than the  Purchase  Price in effect
immediately  prior to the time of such issue or sale, then,  forthwith upon such
issue or sale, the Purchase Price shall be reduced to a price (calculated to the
nearest one  hundredth of a cent)  determined by dividing (1) an amount equal to
the sum of (a) the  number of shares of  Common  Stock  outstanding  immediately
prior to such issue or sale multiplied by the then existing  Purchase Price, and
(b) the consideration,  if any, received by the Company upon such issue or sale,
by (2) the total number of shares of Common Stock outstanding  immediately after
such issue or sale.

     B. For purposes of Subsection A. above,  the following  clauses (1) to (9),
inclusive, shall also be applicable:

               (1) In case at any time the Company shall grant (whether directly
or by  assumption  in a merger or  otherwise)  any rights to subscribe for or to
purchase,  or any  options for the  purchase  of,  Common  Stock or any stock or
securities  convertible into or exchangeable for Common Stock (such  convertible
or exchangeable stock or securities being herein called Convertible  Securities)
whether or not such  rights or options or the right to convert or  exchange  any
such Convertible Securities are immediately exercisable, and the price per share
for which Common  Stock is issuable  upon the exercise of such rights or options
or upon  conversion or exchange of such  Convertible  Securities  (determined by
dividing (a) the total amount,  if any, received or receivable by the Company as
consideration  for the  granting  of such  rights or  options,  plus the minimum
aggregate  amount of  additional  consideration  payable to the Company upon the
exercise of such rights or options,  plus, in the case of such rights or options
which  relate  to  Convertible  Securities,  the  minimum  aggregate  amount  of
additional  consideration,  if  any,  payable  upon  the  issue  or sale of such
Convertible  Securities and upon the conversion or exchange thereof,  by (b) the
total  maximum  number of shares of Common Stock  issuable  upon the exercise of
such  rights  or  options  or  upon  the  conversion  or  exchange  of all  such
Convertible  Securities  issuable  upon the  exercise of such rights or options)
shall be less than the Purchase Price in effect immediately prior to the time of
the granting of such rights or options,  then the total maximum number of shares
of Common  Stock  issuable  upon the  exercise of such rights or options or upon
conversion  or  exchange  of  the  total  maximum  amount  of  such  Convertible
Securities issuable upon the exercise of such rights or options shall (as of the
date of granting of such rights or options) be deemed to be  outstanding  and to
have been  issued  for such price per share.  Except as  provided  in clause (3)
below,  no further  adjustments  of the  Purchase  Price  shall be made upon the
actual  issue  of such  Common  Stock  or of such  Convertible  Securities  upon
exercise of such rights or options or upon the actual issue of such Common Stock
or of such  Convertible  Securities  upon  exercise of such rights or options or
upon the  issue  of such  Common  Stock  upon  conversion  or  exchange  of such
Convertible Securities.

               (2) In case the  Company  shall  issue  (whether  directly  or by
assumption in a merger or otherwise) or sell any Convertible Securities, whether
or not the rights to exchange or convert thereunder are immediately exercisable,
and the price per share for which Common Stock is issuable upon such  conversion
or exchange  (determined by dividing (a) the total amount received or receivable
by the corporation as  consideration  for the issue or sale of such  Convertible
Securities,  plus the minimum aggregate amount of additional  consideration,  if
any, payable to the corporation upon the conversion or exchange thereof,  by (b)
the total maximum  number of shares of Common Stock issuable upon the conversion
or exchange of all such Convertible  Securities) shall be less than the Purchase
Price in effect  immediately  prior to the time of such issue or sale,  then the
total  maximum  number of shares of Common Stock  issuable  upon  conversion  or
exchange of all such  Convertible  Securities shall (as of the date of the issue
or sale of such Convertible  Securities) be deemed to be outstanding and to have
been  issued for such price per share,  provided  that (i) except as provided in
clause (3) below,  no further  adjustments  of the Purchase  Price shall be made
upon the actual issue of such Common Stock upon  conversion  or exchange of such
Convertible  Securities,  and (ii) if any such issue or sale of such Convertible
Securities  is made upon  exercise of any rights to subscribe for or to purchase
or any option to purchase any such Convertible  Securities for which adjustments
of the Purchase  Price have been or are to be made pursuant to other  provisions
of this Subsection B., no further adjustment of the Purchase Price shall be made
by reason of such issue or sale.

               (3) Upon the happening of any of the following events, namely, if
the purchase price  provided in any rights or options  referred to in clause (1)
of this Subsection B., the additional  consideration,  if any,  payable upon the
conversion or exchange of  Convertible  Securities  referred to in clause (1) or
clause  (2) of  this  Subsection  B.,  or the  rate  at  which  any  Convertible
Securities  referred to in clause (1) or clause (2) of this  Subsection  (B) are
convertible into or exchangeable for Common Stock shall change (other than under
or by reason of provisions  designed to protect against dilution),  the Purchase
Price in effect at the time of such event shall  forthwith be  readjusted to the
Purchase  Price  which  would have been in effect at such time had such  rights,
options or Convertible  Securities still  outstanding  provided for such changed
purchase price, additional consideration or conversion rate, as the case may be,
at the time initially granted, issued or sold; and on the expiration of any such
option or right or the termination of any such right to convert or exchange such
Convertible  Securities,  the  Purchase  Price  then in effect  hereunder  shall
forthwith be increased to the Purchase  Price which would have been in effect at
the time of such expiration or termination had such right, option or Convertible
Security,  to the extent  outstanding  immediately  prior to such  expiration or
termination,  never been issued, and the Common Stock issuable  thereunder shall
no longer be deemed to be outstanding. If the purchase price provided for in any
such right or option referred to in clause (1) of this Subsection B. or the rate
at which any Convertible  Securities  referred to in clause (1) or clause (2) of
this Subsection B. are convertible into or exchangeable into or exchangeable for
Common Stock,  shall decrease at any time under or by reason of provisions  with
respect  thereto  designed  to  protect  against  dilution,  then in case of the
delivery of Common  Stock upon the  exercise of any such right or option or upon
conversion or exchange of any such Convertible Security, the Purchase Price then
in effect  hereunder shall  forthwith be adjusted to such  respective  amount as
would have obtained had such rights,  option or Convertible  Security never been
issued as to such Common Stock and had  adjustments  been made upon the issuance
of the shares of Common Stock delivered as aforesaid, but only if as a result of
such  adjustment  the  Purchase  Price  then  in  effect  hereunder  is  thereby
decreased.

     (4) In case  the  Company  shall  declare  a  dividend  or make  any  other
distributions  upon  any  stock  of the  Company  payable  in  Common  Stock  or
Convertible Securities,  any Common Stock or Convertible Securities, as the case
may be, issuable in payment of such dividend or distribution  shall be deemed to
have been issued or sold without consideration.

               (5) In case any shares of Common Stock or Convertible  Securities
or any  rights or options  to  purchase  any such  Common  Stock or  Convertible
Securities shall be issued or sold for cash, the consideration received therefor
shall be deemed to be the  amount  received  by the  Company  therefor,  without
deduction therefrom of any expenses incurred or any underwriting  commissions or
concessions paid or allowed by the Company in connection therewith.  In case any
shares of Common  Stock or  Convertible  Securities  or any rights or options to
purchase any such Common Stock or Convertible Securities shall be issued or sold
for a consideration  other than cash, the amount of the consideration other than
cash  received  by the  Company  shall be  deemed  to be the fair  value of such
consideration  as  determined  in good  faith by the Board of  Directors  of the
Company,  without  deduction  of  any  expenses  incurred  or  any  underwriting
commissions  or  concessions  paid  or  allowed  by the  Company  in  connection
therewith.  In case any shares of Common Stock or Convertible  Securities or any
rights or options to purchase such Common Stock or Convertible  Securities shall
be issued in connection with any merger or consolidation in which the Company is
the surviving corporation,  the amount of consideration therefor shall be deemed
to be the fair value as  determined  by the Board of Directors of the Company of
such  portion of the assets and  business of the  non-surviving  corporation  or
corporations  as such Board shall  determine to be  attributable  to such Common
Stock or Convertible Securities, rights or options, as the case may be.

     (6) In case the  Company  shall take a record of the  holders of its Common
Stock for the  purpose of  entitling  them (a) to  receive a  dividend  or other
distribution  payable in Common Stock or in  Convertible  Securities,  or (b) to
subscribe  for or purchase  Common Stock or  Convertible  Securities,  then such
record date shall be deemed to be the date of the issue or sale of the shares of
Common Stock deemed to have been issued upon the declaration of such dividend or
the making of such other  distribution or the date of the granting of such right
of subscription or purchase, as the case may be.

     (7) The  number of shares of Common  Stock  outstanding  at any given  time
shall not include  shares owned or held or for the account of the  Company,  and
the  disposition  of any such  shares  shall be  considered  an issue or sale of
Common Stock for the purposes of Subsection B.

               (8) Anything in clause (5) of this  Subsection B. to the contrary
notwithstanding, in the case of an acquisition where all or part of the purchase
price is payable in Common Stock or  Convertible  Securities  but is stated as a
dollar amount, where the Company upon making the acquisition pays only part of a
maximum  dollar  purchase  price which is payable in Common Stock or Convertible
Securities  and where the  balance  of such  purchase  price is  deferred  or is
contingently  payable under a formula related to earnings over a period of time,
(a) the  consideration  received for any Common Stock or Convertible  Securities
delivered at the time of the acquisition  shall be deemed to be such part of the
total  consideration  as the portion of the dollar  purchase  price then paid in
Common  Stock or  Convertible  Securities  bears  to the  total  maximum  dollar
purchase price then paid in Common Stock or Convertible  Securities,  and (b) in
connection  with  each  issuance  of  additional  Common  Stock  or  Convertible
Securities  pursuant to the terms of the agreement relating to such acquisition,
the  consideration  received  shall  be  deemed  to be such  part  of the  total
consideration  as the portion of the dollar  purchase price then and theretofore
paid in Common Stock or Convertible Securities bears to the total maximum dollar
purchase price payable in Common Stock or Convertible Securities multiplied by a
fraction,  the  numerator of which shall be the number of shares (or in the case
of Convertible Securities other than stock, the aggregate principal amount) then
issued and the  denominator  of which shall be the total number of shares (or in
the case of Convertible  Securities  other than stock,  the aggregate  principal
amount) then and theretofore issued under such acquisition  agreement.  If it is
determined that any part of the deferred or contingent  portion of such purchase
price shall not be payable,  the Purchase Price then in effect  hereunder  shall
forthwith be readjusted to such Purchase Price as would have obtained (i) ha the
adjustment made in connection with such  acquisition been made upon the basis of
the  issuance  of only the  number  of shares  of  Common  Stock or  Convertible
Securities  actually  issued in connection with such  acquisition,  and (ii) had
adjustments  been made on the basis of the Purchase  Price as adjusted in clause
(1) for all issued or sale (as prices which would have  affected  such  adjusted
Purchase  Price) of Common Stock or rights,  options or  Convertible  Securities
made after such acquisition. In the event that only a part of the purchase price
for an  acquisition  is paid in Common Stock or  Convertible  Securities  in the
manner referred to in this clause (8), the term"total  consideration" as used in
this clause (8) shall mean that part of the aggregate consideration as is fairly
allocable to the purchase price paid in Common Stock or  Convertible  Securities
in the manner  referred to in this clause  (8),  as  determined  by the Board of
Directors of the Company.

     (9)  Notwithstanding  anything  to the  contrary  in this  Section  II., no
adjustment in the Purchase  Price shall result,  pursuant to Subsection A. above
or otherwise,  from the issuance by the Company of shares of its Common Stock as
a result of the following transactions:

     (a) The  exercise of options  heretofore  or  hereafter  granted  under the
Company's 1986 Incentive Stock Option Plan, as the same may be amended, extended
or substituted  from time to time provided,  that the number of shares available
thereunder   may  not  be  increased  by  any  such   amendment,   extension  or
substitution; and

     (b) The  exercise of options  heretofore  or  hereafter  granted  under the
Company's  1993 Stock  Option  Plan,  as the same may be  amended,  extended  or
substituted  from time to time  provided,  that the  number of shares  available
thereunder   may  not  be  increased  by  any  such   amendment,   extension  or
substitution.

     C. In case the  Company  shall  declare a dividend  upon the  Common  Stock
payable  otherwise  than out of  consolidated  earnings or  consolidated  earned
surplus, determined in accordance with generally accepted accounting principles,
including the making of appropriate deductions for minority interest, if any, in
subsidiary  corporations,  and  otherwise  than in Common  Stock or  Convertible
Securities,  the Company shall give the holders of each Warrant thirty (30) days
prior  written  notice of the date as of which the  holders  of Common  Stock of
record entitled to such special  dividend shall be determined.  For the purposes
of the foregoing a dividend  other than in cash shall be considered  payable out
of earnings or surplus (other than  revaluation or paid-in  surplus) only to the
extent that such  earnings  or surplus  are charged an amount  equal to the fair
value of such dividend as determined by the Board of Directors of the Company.

     D. (1) In case the  Company  shall at any time  subdivide  its  outstanding
shares of Common Stock into a greater  number of shares,  the Purchase  Price in
effect immediately prior to such subdivision shall be  proportionately  reduced,
and,  conversely  (2) in case the  outstanding  shares  of  Common  Stock of the
Company shall be combined into a smaller number of shares, the Purchase Price in
effect immediately prior to such combination shall be proportionately increased.

     E. In case of any capital  reorganization  or any  reclassification  of the
Common Stock of the Company,  the consolidation of Company with or the merger of
Company with or into any other  corporation,  or the sale of the  properties and
assets of Company as, or substantially as, an entirety to any other corporation,
then each  holder of a Warrant  then  outstanding  shall be entitled to purchase
such number of shares of stock or other securities or property of Company or any
other  corporation   resulting  from  such   reorganization,   reclassification,
consolidation,  merger,  or sale,  as was  exchanged for the number of shares of
Common Stock of Company  which the holder  would have been  entitled to purchase
except for such action. The subdivision or combination of shares of Common Stock
at any time  outstanding  into a greater  or  lesser  number of shares of Common
Stock  shall not be  deemed  to be a  reclassification  of the  Common  Stock of
Company for the purposes of this Subsection"E."

     F. (1) Except as provided in Subsection G, to follow,  upon each adjustment
of the  Purchase  Price as a result of (a) an issuance  or sale of Common  Stock
below the Purchase  Price as provided in  Subsections  A and B above,  including
(without  limitation) a dividend or  distribution in shares of capital stock, or
(b) a  subdivision  of  outstanding  shares  of  Common  Stock  as  provided  in
Subsection "D.(1)" hereof, the number of shares of Common Stock purchasable upon
exercise of any Warrant  Certificate  shall be increased to the number of shares
of Common Stock  (calculated to the nearest  hundredth)  obtained by multiplying
(i) the number of shares of Common Stock  purchasable  immediately prior to such
adjustment upon exercise of Warrants  (evidenced by the Warrant Certificate held
by such holder) by (ii) the Purchase Price in effect  immediately  prior to such
adjustment, and dividing the product so obtained by the Purchase Price in effect
after such adjustment.

     (2) Except as provided in Subsection "G" to follow, upon each adjustment of
the Purchase  Price as a result of a combination of the Common Stock as provided
in Subsection  "D.(2)" hereof,  the number of shares of Common Stock purchasable
upon  exercise of any Warrant  Certificate  shall be  decreased to the number of
shares of  Common  Stock  (calculated  to the  nearest  hundredth)  obtained  by
multiplying  (a) the number of shares of Common  Stock  purchasable  immediately
prior to such  adjustment  upon  exercise of Warrants  evidenced  by the Warrant
Certificate held by such holder, by (b) the Purchase Price in effect immediately
prior to such  adjustment,  and then  dividing  the  product so  obtained by the
Purchase Price in effect after such adjustment.

     G. In lieu of an adjustment  in the number of shares  covered by a Warrant,
Company may elect, on or after the date of any adjustment of the Purchase Price,
to adjust the number of Warrants.

     H.  Irrespective  of any adjustments or change in the Purchase Price or the
number of shares of the Common Stock issuable upon the exercise of the Warrants,
the Warrant  Certificates  theretofore  and  thereafter  issued may  continue to
express  the  Purchase  Price  per share and the  number  of shares  which  were
expressed upon the Warrant Certificates when initially issued.

     I. Before  taking any action which would cause an  adjustment  reducing the
Purchase  Price below the then par value,  if any, of the shares of Common Stock
issuable upon exercise of the Warrants,  Company shall take any corporate action
which may, in the opinion of its counsel, be necessary in order that Company may
validly and legally  issue  fully paid and  nonassessable  shares of such Common
Stock at such adjusted Purchase Price.

     J.  Whenever  the  Purchase  Price,  the  number of shares of Common  Stock
issuable  upon the  exercise  of each  Warrant,  or the number of  Warrants  are
adjusted as provided in this  Section  II.,  Company  shall  promptly  prepare a
certificate  setting  forth the  Purchase  Price as so  adjusted,  the number of
shares  of  Common  Stock  issuable  upon the  exercise  of each  Warrant  as so
adjusted, and a brief statement of the facts accounting for such adjustment.

     K. If any event occurs as to which in the opinion of the Board of Directors
of the  Company  the other  provisions  of this  Section  II.  are not  strictly
applicable or if strictly  applicable  would not fairly  protect the  conversion
rights of the holders of the Warrants in accordance  with the  essential  intent
and  principles of such  provisions,  then the Board of Directors  shall make an
adjustment  in the  application  of such  provisions,  in  accordance  with such
essential  intent and  principles,  so as to  protect  such  exercise  rights as
aforesaid. III. A. This Certificate, with or without other Warrant Certificates,
upon  surrender at the  principal  office of the Company,  may be exchanged  for
another Warrant  Certificate or Warrant  Certificates  of like tenor  evidencing
Warrants  entitling the holder to purchase a like aggregate  number of Shares as
the  Warrants  evidenced  by the  Warrant  Certificate  or Warrant  Certificates
surrendered.  If only a part of the Warrants  evidenced by this  Certificate are
exercised,  the holder  hereof  shall be  entitled to  receive,  upon  surrender
hereof,  another Warrant  Certificate or Warrant  Certificates for the number of
whole Warrants not exercised.

     B. Upon receipt by Company of evidence reasonably satisfactory to it of the
loss, theft, destruction,  or mutilation of a Warrant Certificate,  and, in case
of loss, theft, destruction,  or mutilation, of indemnity or security reasonably
satisfactory  to it, and  reimbursement  to Company of all  reasonable  expenses
incidental  thereto,  and upon surrender to the Company and  cancellation of the
Warrant Certificate,  if mutilated,  the Company shall deliver to the registered
owner a new Warrant Certificate in lieu of, and evidencing the right to purchase
the same  number  of  shares  as,  the  Warrant  Certificate  so  lost,  stolen,
destroyed, or mutilated.

     C. No  holder  of the  Warrants  evidenced  by this  Certificate  shall  be
entitled to vote or receive  dividends  or be deemed the holder of Shares or any
other securities of Company which may at any time be issuable on the exercise of
these  Warrants for any  purpose,  nor shall  anything  contained in the Warrant
Agreement or herein be construed to confer upon the holder of these Warrants, as
such, any of the rights of a shareholder of Company or any right to vote for the
election  of  directors  or upon any matter  submitted  to  shareholders  at any
meeting thereof, or to give or withhold consent to any corporate action (whether
upon any recapitalization,  issue of stock, reclassification of stock, change of
par value, consolidation, merger, conveyance, or otherwise) or to receive notice
of meetings, or to receive dividends or subscription rights or otherwise,  until
the Warrants  evidenced by this Warrant  Certificate have been exercised and the
Common Stock purchasable upon the exercise thereof has become deliverable.

     D. To the extent that any Warrant  Certificates  remain outstanding at 5:01
P.M.  central  standard time on the Expiration  Date, such  outstanding  Warrant
Certificates  shall be  automatically  deemed exercised on behalf of each record
holder of Warrant  Certificates into shares of the Company's Common Stock at the
rate ("Conversion Rate") of one-tenth (1/10) of a share of Common Stock for each
Warrant  Certificate  or  Certificates  representing,   immediately  before  the
Expiration Date, the right to purchase one share of Common Stock.

     E.  Upon  the  exercise  of the  Warrant,  in lieu of the  issuance  of any
fractional  Shares,  the Company shall pay cash to the registered  holder of the
Warrant based on the  difference  between the market price of the Shares,  which
price  shall be  computed  as the per Share  closing  price (if such  Shares are
listed on an exchange) or the average between the per Share bid and asked prices
as of the close of business  on the  exercise  date as reported by the  National
Association of Securities  Dealers  Automated  Quotation System and the Purchase
Price on the exercise date times the  fractional  Share which is  represented by
the Warrants on the exercise date.  However, if no market price exists, then the
amount of cash to be paid to the registered holder of the Warrant in lieu of any
fractional  Shares shall be the product of the difference  between the per share
Tangible  Net Book Value  (defined  hereafter)  of the  shares of the  Company's
Common Stock outstanding on the last business day prior to the exercise date and
the Purchase  Price on the exercise  date times the  fractional  security  which
otherwise  would  have been  issuable  in the  absence  of this  provision.  For
purposes of payment of cash in lieu of the  issuance of  fractional  securities,
the  term"Tangible  Net Book Value" means the consolidated  total  shareholders'
equity,  determined in accordance with generally accepted accounting  principles
("GAAP"), less the aggregate net amount of the following items to the extent, if
any,  that  they  were  included  in   consolidated   assets  or  deducted  from
consolidated liabilities in computing shareholders' equity:

     (i) all franchises,  licenses,  patents,  patent applications,  copyrights,
trademarks,  trade names,  goodwill,  experimental  or  organizational  expense,
unamortized debt discount and expense, and all other assets which under GAAP are
deemed intangible; and,

               (ii) any write-up of assets after December 31, 1998.

          F. The holder  hereof,  by  accepting  same,  consents and agrees with
Company and with every other holder of a Warrant Certificate that:

     (1) The Warrants evidenced by this Certificate are transferable only on the
registry  books  of the  Company  upon  surrender  of  this  Certificate  at the
principal office of the Company and only as provided below;

     (2)  Company  and may  deem  and  treat  the  person  in  whose  name  this
Certificate  is  registered  as the absolute  owner  thereof and of the Warrants
evidenced thereby  (notwithstanding any notations of ownership or writing on the
Certificate made by anyone other than Company) for all purposes whatsoever,  and
the Company shall not be affected by any notice to the contrary; and

     (3) Company may modify the terms of the Warrant from time to time.

     G. The  registered  holder of any Warrant  Certificate  may  exercise it in
whole or in part at any time,  but only in such  multiples  as are  required  to
permit the  issuance  by  Company of one or more  shares,  by  surrender  of the
Warrant  Certificate  with the form of election to purchase on the reverse  side
thereof duly executed,  to the Company at the principal office of the Company at
or prior to 5:00 P.M. central standard time on July 31, 2009, or such later date
or dates as Company may determine  together with payment of the Purchase  Price,
payable to Company, for each share into which the Warrants are exercised.

     H. Upon  receipt of a Warrant  Certificate,  with the form of  election  to
purchase duly  executed,  accompanied  by payment of the Purchase  Price for its
shares to be  purchased  and an amount equal to any  applicable  transfer tax in
cash,  or by  certified  check,  bank  draft,  or postal or express  money order
payable  to the  order  of  Company,  the  Company  shall  thereupon  cause  the
certificates  for the number of whole  shares to be purchased to be delivered to
or  upon  the  order  of the  registered  holder  of  such  Warrant  Certificate
registered in such name or names as may be designated by such holder.

     I. In case the registered holder of any Warrant Certificate  exercises less
than all the Warrants evidenced thereby,  a new Warrant  Certificate  evidencing
Warrants  equivalent to the Warrants  remaining  unexercised  shall be issued by
Warrant Agent to the  registered  holder of such Warrant  Certificate or to such
holder's duly authorized assigns.

          J. Each  person in whose  name any  certificate  for  shares of Common
Stock of the  Company is issued  upon the  exercise  of  Warrants  shall for all
purposes  be deemed to have  become the holder of record of the shares of Common
Stock represented thereby on, and such certificate shall be dated, the date upon
which the Warrant Certificate  evidencing such Warrants was duly surrendered and
payment of the  Purchase  Price (and any  applicable  transfer  taxes) was made;
provided, however, that if the date of such surrender and payment is a date upon
which the transfer  books of Company are closed,  such person shall be deemed to
have become the record holder of such shares on, and such  certificate  shall be
dated,  the next succeeding  business day on which the transfer books of Company
are open. Prior to the exercise of the Warrants evidenced thereby, the holder of
a Warrant  Certificate  shall not be entitled to any rights of a shareholder  of
Company  with  respect  to  shares  for  which  the  Warrants  are  exercisable,
including,  without limitation, the right to vote, to receive dividends or other
distributions,  or to exercise any preemptive  rights, and shall not be entitled
to receive any notice of any proceedings of Company, except as provided herein.

          WITNESS the facsimile signatures of the proper officers of Company and
its corporate seal. Dated as of July 30, 1999.

                              TGC INDUSTRIES, INC.


                              By:  /s/ Allen T. McInnes
                                   _____________________________
                                       Allen T. McInnes,
                                     Chairman of the Board
ATTEST:


By:    /s/ Kenneth W. Uselton
       _______________________________
          Kenneth W. Uselton,
         Assistant Secretary



<PAGE>




                                  ASSIGNMENT

                 (To be executed by the registered holder if such
                holder desires to transfer the Warrant Certificate)

     FOR  VALUE  RECEIVED  _____________________________________  hereby  sells,
assigns, and transfers unto ______________________

     (Please print name and address of transferee)

- ------------------------------------------------------------------
this Warrant Certificate,  together with all right, title, and interest therein,
and does hereby irrevocably  constitute and appoint  ___________________________
Attorney,  to  transfer  the  within  Warrant  Certificate  on the  books of the
within-named Company, with full power of substitution.

Dated: ________________________ , 19____.

                                        -------------------------
                                                       Signature

                                        -------------------------
                                              Signature Guaranteed

     NOTICE:  The  signature(s)  to this  assignment  must  correspond  with the
name(s) as written upon the face of the Certificate in every particular  without
alteration  or  enlargement  or  any  change  whatever.   Signature(s)  must  be
guaranteed  by a  commercial  bank or trust  company or a member firm of a major
stock exchange.






<PAGE>




     ELECTION TO PURCHASE

     (To be executed if holder desires
     to exercise the Warrant Certificate)
     To: TGC INDUSTRIES, INC.

          The undersigned hereby irrevocably elects to exercise ________________
Warrants  represented  by this  Warrant  Certificate  to purchase  the shares of
Common  Stock  issuable  upon the exercise of such  Warrants  and requests  that
certificates for such shares be issued in the name of:

- ------------------------------------------------------------------
     (Please insert social security or other identifying number)

- ------------------------------------------------------------------
     (Please print name and address)

          If such number of Warrants  does not  constitute  all of the  Warrants
evidenced by this Warrant Certificate, a new Warrant Certificate for the balance
remaining of such Warrants shall be registered in the name of and delivered to:

- ------------------------------------------------------------------
     (Please insert social security or other identifying number)

- ------------------------------------------------------------------

Dated: ____________________, 19_________

                                        -------------------------
                                                       Signature

                                        -------------------------
                                              Signature Guaranteed

     NOTICE:  The signature on this Form of Election to Purchase must correspond
with the name(s) as written upon the face of the Certificate  without alteration
or  enlargement  or any change  whatever.  Signature(s)  must be guaranteed by a
commercial bank or trust company or a member firm of a major stock exchange.





<PAGE>
















                               EXHIBIT 10.11

                         DEBENTURE PURCHASE AGREEMENT

                                   BETWEEN

                             TGC INDUSTRIES, INC.

                                     AND

                          WEDGE ENERGY SERVICES, L.L.C.


<PAGE>


                              TABLE OF CONTENTS

                                                                        Page

ARTICLE I

     PURCHASE OF CONVERTIBLE DEBENTURE

     1.1     Purchase by WEDGE
     1.2     Note Payment

ARTICLE II
     ADDITIONAL FINANCING

     2.1     Grant of Right of Participation
     2.2     Procedure.

ARTICLE III

     CONVERSION OPTIONS OF WEDGE

     3.1     Conversion into Senior Convertible Preferred Stock
     3.2     Conversion into Series D Convertible Preferred Stock
     3.3     Conversion into Common Stock
     3.4     Manner of Conversion
     3.5     Redemption of Preferred Stock

ARTICLE IV
     PREPAYMENT OF DEBENTURE

     4.1     Optional Prepayment of Debenture and Notice of Prepayments
     4.2     Allocation of Prepayments
     4.3     Merger or Sale

ARTICLE V
     REGISTRATION RIGHTS

     5.1     Registration on Request
     5.2     Incidental Registration
     5.3     Registration Procedures
     5.4     Registration Expenses
     5.5     Indemnification

ARTICLE VI
     AFFIRMATIVE COVENANTS

     6.1     Preferred Shareholders' Consent.
     6.2     Board Seats
     6.3     Inspection of Property, Books and Records

ARTICLE VII
     NEGATIVE COVENANTS

     7.1     No Cash Dividends.

     7.2     Prohibition Against Capital Expenditures

     7.3     Reorganization, Stock Dividends, Reclassification, Subdivision or
               Stock Issuances

ARTICLE VIII

     REPRESENTATIONS AND WARRANTIES BY THE COMPANY
     8.1     Organization and Existence, Etc.
     8.2     Financial Statements, Etc.
     8.3     Business
     8.4     Litigation
     8.5     No Material Adverse Contracts, Etc.
     8.6     Compliance with Instruments, Etc
     8.7     Tax Returns and Liabilities
     8.8     Permits, Governmental and Other Approvals
     8.9     Patents, Trademarks and Other Rights

    8.10     Consents

    8.11     Shares to be Fully Paid; Reservation of Shares
    8.12     Key Employees
    8.13     Survival
    8.14     Opinion of Counsel

ARTICLE IX

    DEFAULT
    9.1     Event of Default.
    9.2     Default Remedies.

ARTICLE X

    MISCELLANEOUS
    10.1     Conflict of Agreement
    10.2     Counterparts
    10.3     Amendments
    10.4     Governing Law
    10.5     Severability
    10.6     Injunctive Relief
    10.7     Term
    10.8     Notices

    10.9     Headings.
    10.10    Costs

                         DEBENTURE PURCHASE AGREEMENT

     THIS DEBENTURE PURCHASE  AGREEMENT (the "Agreement"),  is entered into this
10th day of December,  1999,  among TGC  INDUSTRIES,  INC.  (the  "Company"),  a
corporation  incorporated  under the laws of the State of Texas, whose principal
place of  business  is at 1304 Summit  Avenue,  Suite 2, Plano,  Texas 75704 and
WEDGE ENERGY SERVICES,  L.L.C., a limited  liability company organized under the
laws of the State of  Delaware,  whose  principal  place of  business is at 1415
Louisiana, Suite 3000, Houston, Texas 77002 ("WEDGE").

                                R E C I T A L S

     WHEREAS, on the date hereof, the Company will simultaneously issue to WEDGE
a 8-1/2%  Convertible  Subordinated  Debenture,  Series  B, and  enter  into the
Debenture Agreement of even date herewith in the form attached hereto as Exhibit
A (collectively,  hereinafter  referred to as the  "Debenture")  pursuant to the
payment of $2,500,000 cash by WEDGE to the Company;

     WHEREAS,  WEDGE has  previously  loaned to the Company the amount  $300,000
evidenced  by the certain  Advance  Note  executed by the Company and payable to
WEDGE dated November 1, 1999 (the "Note"); and

     WHEREAS, in connection with the issuance of the Debenture and the repayment
of the Note, the parties have agreed,  among other things,  that WEDGE will have
the right to convert the  Debenture  as provided  therein and the right of first
refusal to participate in all future debt or equity offerings in the Company;

     NOW, THEREFORE, the parties agree as follows:

                                   ARTICLE I
                        PURCHASE OF CONVERTIBLE DEBENTURE

     1.1 Purchase by WEDGE.  The Company hereby agrees to sell, and WEDGE agrees
to  purchase,  the  8-1/2%  Convertible  Subordinated  Debenture,  Series B, due
December 1, 2009,  for the  aggregate  amount of  $2,500,000  payable upon WEDGE
tendering to the Company, by wire transfer, the cash sum of $2,500,000. Attached
hereto as  Exhibit A is the form of  Debenture  which  sets  forth all rights of
WEDGE,  as a holder of such  Debenture,  and all duties and  obligations  of the
Company, as the issuer of same.

     1.2 Note Payment.  Upon receipt of the  Debenture  and the cashier's  check
described  herein in payment of the Note,  WEDGE shall return the fully executed
Note,  marked  cancelled,  and  cause  all  collateral  securing  the Note to be
released,  including,  without  limitation,  the  release  of and  return to the
Company of all title documents to vehicles held by WEDGE as collateral.

                                ARTICLE II
                           ADDITIONAL FINANCING

     2.1 Grant of Right of  Participation.  The Company  hereby  grants  WEDGE a
right of participation  to participate in any additional  equity offerings which
the Company may offer,  up to the WEDGE  Percentage (as defined  below),  on the
following  terms and  conditions.  In the event that the Company has  received a
bona fide offer  (which the  Company  desires  to  accept)  with  respect to the
issuance of any equity securities (including,  without limitation, any common or
preferred stock, any options  (excluding the Company's 1993 Stock Option Plan or
any future  employee stock option plan approved by the Company's  shareholders),
warrants,  rights,  unsecured convertible notes, convertible debentures or other
convertible  securities),  the Company  shall  immediately  give written  notice
thereof (the  "Notice")  to WEDGE.  The Notice shall state the name of the party
proposing to provide the offering and all the pertinent  terms and conditions of
such offering. This right shall expire upon the later to occur of the following:
(a) the maturity of the  Debenture,  (b) the  conversion of the  Debenture  into
Common Stock, (c) the conversion of the Debenture into Senior Preferred Stock or
Series D Preferred Stock (as defined below) and the conversion of such Preferred
Stock into Common Stock, or (d) the tenth anniversary of the date hereof.

     2.2 Procedure. WEDGE shall have fourteen (14) days from the date the Notice
was given to  indicate to the  Company,  in writing,  that WEDGE  undertakes  to
participate  in the  offering  under the terms and  conditions  set forth in the
Notice.  If WEDGE  undertakes to participate in such offering,  then the Company
shall be obligated to accept such  participation up to the WEDGE Percentage upon
the terms and conditions set forth in the Notice and the parties shall use their
best efforts to enter into a definitive agreement relating to such offering.  In
the event that WEDGE declines to participate in such offering, the Company shall
have  the  right  to  accept  such   offering   from  the  third  party  without
participation  by WEDGE  provided that it does so upon the terms and  conditions
set forth in the  Notice.  In the event that such  offering  is not  consummated
within  sixty (60) days after the date the Notice was given,  the Company  shall
not consummate such offering without again complying with this Section 2.2.

     2.3 WEDGE  Percentage.  For  purposes  of this  Agreement,  the term "WEDGE
Percentage" shall mean that percentage calculated,  on a fully diluted basis, as
if WEDGE had (a) converted the Debenture  into Common Stock,  which number shall
constitute the  numerator,  and (b) divided by the  denominator,  which shall be
equal to the total number of shares of Common Stock issued and outstanding as of
such date,  plus (i) that  number of shares of Common  Stock  issuable  upon the
conversion  of all  convertible  securities of the Company,  including,  without
limitation,  the  Debenture,  and (ii) that  number  of  shares of Common  Stock
issuable  upon the exercise of all options and warrants  utilizing the "treasury
method" as of such date.  Under the treasury  method,  only shares issuable upon
the  exercise  of "in the money"  options and  warrants  are  considered  in the
calculation  and the net  dilution is that number of shares  issuable  upon such
exercise  net of such shares which could have been  purchased  with the proceeds
from the  exercise  of the options and  warrants at the then market  price.  For
example, assuming 100,000 options are outstanding at a strike price of $1.00 per
share and that the market  price of the Common  Stock is $2.50 per share,  under
the treasury  method,  the proceeds from the exercise of the options would equal
$100,000 and such proceeds would  purchase  40,000 shares of Common Stock at the
market price of $2.50 per share. The net dilution is 60,000 shares, which number
of shares is utilized in the calculation of the WEDGE Percentage under the above
formula.

                                 ARTICLE III
                          CONVERSION OPTIONS OF WEDGE

     3.1 Conversion into Senior  Convertible  Preferred Stock ("Senior Preferred
Stock").  The Debenture shall provide that WEDGE shall have the right to convert
its Debenture  into Senior  Preferred  Stock at an initial  conversion  price of
$1.15 per share, in the event the Company is able to obtain consent from holders
of the Company's 8% Series C Convertible Exchangeable Preferred Stock ("Series C
Preferred  Stock")  required in accordance  with the  designations  filed in the
Office of the Secretary of State of Texas ("Texas  Secretary of State").  If the
Company is able to obtain  consent of 66-2/3% of the  ownership  interest of the
holders of the Series C Preferred  Stock,  the  Company  shall cause to be filed
with the Texas Secretary of State those designations,  rights and preferences in
the form  substantially  similar to Exhibit "B" attached hereto, and WEDGE shall
automatically convert its Debenture into Senior Preferred Stock.

     3.2 Conversion into Series D Convertible  Preferred Stock. In the event the
Company is  unsuccessful  in obtaining the waiver  required in Section 3.1 above
within  ninety (90) days from the date hereof,  WEDGE shall have the right,  but
not the  obligation,  to elect to  convert  the  Debenture  into a new series of
preferred stock ("Series D Preferred  Stock") at an initial  conversion price of
$1.15 per  share,  which  shall  rank pari  passu  with the  Company's  Series C
Preferred  Stock,  or any series of  preferred  stock of the Company with rights
superior thereto,  and as long as the initial  conversion price is $1.15. In the
event WEDGE shall  thereafter  elect to convert its preferred  stock into Common
Stock,  then the  preferred  stock may be  converted  into  Common  Stock at the
initial  conversion  ratio  of one  share of  Common  Stock  for  each  share of
preferred  stock.  If WEDGE  elects to convert its  Debenture  into the Series D
Preferred Stock, the Company will immediately prior to such election cause to be
filed  with  the  Texas  Secretary  of  State  those  designations,  rights  and
preferences consistent with this Section 3.2 which shall encompass the terms and
conditions set forth in Exhibit "C" attached hereto.

     3.3 Conversion into Common Stock. At any time the Debenture is outstanding,
or at any time after the Debenture has been converted  into  preferred  stock as
provided in Sections 3.1 or 3.2 above,  WEDGE may elect to convert its Debenture
or preferred stock into Common Stock at an initial conversion price of $1.15 per
share, or WEDGE may elect to convert its preferred stock into Common Stock at an
initial  conversion  ratio  of one  share of  Common  Stock  for  each  share of
preferred stock.

     3.4 Manner of  Conversion.  Any  Debenture  which is to be converted in any
manner described in this Article 3 shall be converted in accordance with Section
8.02 of the Debenture.  The conversion  price is subject to adjustment from time
to time in accordance with Section 8.05 of the Debenture.

     3.5  Redemption  of  Preferred  Stock.  The Company  may, at any time after
December 1, 2001, redeem any or all shares of Senior Preferred Stock or Series D
Preferred Stock  outstanding at an initial  redemption price of $1.75 per share,
subject to  adjustment  from time to time in  accordance  with the terms of such
Preferred  Stock.  The Company  shall give  written  notice of its  intention to
redeem no less than thirty (30) days before the date fixed for redemption.  Such
notice shall state (i) the date of redemption,  and (ii) the number of shares of
Preferred Stock which are being elected to be redeemed.

                               ARTICLE IV
                         PREPAYMENT OF DEBENTURE

     4.1 Optional Prepayment of Debenture and Notice of Prepayments. The Company
may, at any time after  December 1, 2001,  prepay the  Debenture  in whole or in
part (in  amounts  of not less than  $50,000)  by  payment  of  152.174%  of the
principal amount of the Debenture, or portion thereof to be prepaid, and payment
of the accrued interest  thereon to the date of prepayment.  Except as set forth
herein or in the  Debenture,  the Company may not prepay the Debenture  prior to
maturity.  The  Company  shall  give  written  notice of any  prepayment  of the
Debenture pursuant to Section 3.01 of the Debenture,  to each holder thereof not
less than  thirty  (30) days nor more than sixty (60) days before the date fixed
for such optional prepayment.  Such notice shall specify (i) such date, and (ii)
the principal  amount of the holder's  Debenture to be prepaid and the aggregate
principal  amount of the Debenture to be prepaid.  Notice of  prepayment  having
been so given,  152.174%  of the  aggregate  principal  amount of the  Debenture
specified in such notice,  and the accrued interest thereon shall become due and
payable on the prepayment date.

     4.2  Allocation of  Prepayments.  All partial  prepayments of the Debenture
shall be applied to the unpaid principal amounts of the Debenture.

     4.3 Merger or Sale. In the event of the consolidation with or merger of the
Company with or into another corporation or entity, or in the event of the sale,
lease or  conveyance  to  another  corporation  or entity  of the  assets of the
Company as an entirety or substantially  as an entirety,  then, upon the written
request of WEDGE,  the Company shall prepay the Debenture in whole by payment of
100% of the  principal  amount  of the  Debenture  and  payment  of the  accrued
interest  thereon  to the date of  prepayment,  within  thirty  (30) days of the
Company's receipt of such written request.

                                   ARTICLE V
                              REGISTRATION RIGHTS

     5.1 Registration on Request.  Upon the written request of WEDGE of at least
51% in the aggregate  principal amount of the Debenture and/or 51% of the shares
of Common Stock,  Senior  Preferred  Stock and/or Series D Preferred  Stock (the
"Shares") issued upon conversion of the Debenture, which request shall state the
intended  method of  disposition  by WEDGE and shall  request  that the  Company
effect the  registration  of all or part of such Shares,  or the Shares issuable
upon the conversion of the Debenture, or both, under the Securities Act of 1933,
as amended (the "Act"),  the Company will promptly  give written  notice of such
requested  registration  to WEDGE,  and  thereupon  will use its best efforts to
effect the registration under the Act of:

     (a) the Shares which the Company has been so  requested  to  register,  for
disposition in accordance with the intended method of disposition stated in such
request, and

     (b) all other outstanding Shares, or Shares issuable upon the conversion of
the Debenture, the holders of which shall have made written request (stating the
intended  method of  disposition  of such  securities  by such  holders)  to the
Company for  registration  thereof  within thirty (30) days after the receipt of
such written notice from the Company,  all to the extent requisite to permit the
disposition  (in accordance  with the intended  methods thereof as aforesaid) by
the holders of the Shares so  registered  and to maintain such  registration  in
effect for a period of twenty-four (24) months; provided, that the Company shall
not be required to register or use its best  efforts to effect any  registration
of Shares under the Act  pursuant to Section  11.01 of the  Debenture  more than
once.

     The Company shall have no obligation to register or use its best efforts to
effect any registration of Shares under the Act pursuant to this Article V which
would be in conflict with the obligations of any holder or holders of Debentures
and/or Shares under any confidentiality agreement between such holder or holders
and the Company  entered into in connection  with the offering of the Debentures
to such holder or holders.  In the event that, as a result of such registration,
another  person  with  incidental  registration  rights  granted by the  Company
requests   that  the  Company   include   securities  of  such  person  in  such
registration,  such  request  will not  result in a  reduction  in the number of
securities of WEDGE to be included in such registration.

     5.2  Incidental  Registration.  If the  Company  at any  time  proposes  to
register any of its securities under the Act (otherwise than pursuant to Section
11.01 and other than a  registration  on Form S-8,  or the form,  if any,  which
supplants such Form), it will each such time give written notice to WEDGE of its
intention to do so and,  upon the written  request of WEDGE  within  thirty (30)
days after the  receipt of any such  notice  (which  request  shall  specify the
Shares  intended to be disposed of by such holder and state the intended  method
of disposition thereof), the Company will use its best efforts to cause all such
outstanding Shares, or Shares issuable upon the conversion of the Debenture, the
holders  of which  shall  have so  requested  the  registration  thereof,  to be
registered  under the Act to the extent  requisite to permit the disposition (in
accordance  with the intended  methods  thereof as  aforesaid)  of the Shares so
registered;  provided  that,  if in the  good  faith  judgment  of the  managing
underwriter or  underwriters of a then proposed public offering of the Company's
securities,  such  registration  of such Shares would  materially  and adversely
affect such public  offering,  then in such event the number of Shares and other
securities  to be  registered  by the Company,  including,  without  limitation,
securities to be registered pursuant to any other registration rights which have
been granted by the Company, shall each be proportionally reduced to such number
as shall be acceptable to the managing underwriter.

     5.3 Registration Procedures. If and whenever the Company is required to use
its best efforts to effect or cause the registration of any Shares under the Act
as provided in Article XI of the Debenture,  the Company will, as  expeditiously
as possible:

     (a)  prepare  and  file  with  the  Securities   and  Exchange   Commission
(the"Commission")  a registration  statement with respect to such Shares and use
its best efforts to cause such registration statement to become effective;

     (b) prepare and file with the Commission such amendments and supplements to
such registration  statement and the prospectus used in connection  therewith as
may be necessary to keep such registration  statement  effective for such period
not  exceeding  twenty-four  (24) months as may be  necessary to comply with the
provisions of the Act with respect to the  disposition  of all Shares covered by
such  registration  statement during such period in accordance with the intended
methods  of  disposition  by the  seller or  sellers  thereof  set forth in such
registration statement;

     (c)  furnish to each  seller of such  Shares  such number of copies of such
registration  statement and of each such  amendment and  supplement  thereto (in
each case  including  all  exhibits),  such  number of copies of the  prospectus
included in such registration  statement (including each preliminary  prospectus
and, if any seller shall so request, a summary  prospectus),  in conformity with
the  requirements  of the Act,  and such  other  documents,  as such  seller may
reasonably request in order to facilitate the disposition of the Shares owned by
such seller;


     (d) use its best efforts to register or qualify such Shares covered by such
registration  statement  under  such other  securities  or blue sky laws of such
jurisdictions as each seller shall reasonably request,  and do any and all other
acts and things  which may be  reasonably  necessary or advisable to enable such
seller to consummate the disposition in such  jurisdictions  of the Shares owned
by such seller; and

     (e) notify  each  seller of any such  Shares  covered by such  registration
statement,  at any time when a  prospectus  relating  thereto is  required to be
delivered  under the Act within the period  mentioned in subdivision (b) of this
Section  11.03 of the  Debenture,  of the  happening of any event as a result of
which the prospectus included in such registration statement, as then in effect,
includes an untrue  statement of a material  fact or omits to state any material
fact required to be stated therein or necessary to make the  statements  therein
not  misleading  in the light of the  circumstances  then  existing,  and at the
request of any such  seller  prepare  and  furnish to such  seller a  reasonable
number of copies of a supplement to or an amendment of such prospectus as may be
necessary so that,  as  thereafter  delivered to the  purchasers of such Shares,
such prospectus shall not include an untrue statement of a material fact or omit
to state a material fact required to be stated  therein or necessary to make the
statements  therein  not  misleading  in the  light  of the  circumstances  then
existing.

     5.4  Registration   Expenses.   All  expenses  incident  to  the  Company's
performance of or compliance with this Article V, including, without limitation,
all registration and filing fees, fees and expenses of complying with securities
or blue sky laws,  printing  expenses and fees and  disbursements of counsel for
the Company and of independent public  accountants,  but excluding  underwriting
commissions  and discounts,  the fees of any counsel  engaged by WEDGE,  and any
filing fees associated with shares of either Senior Convertible  Preferred Stock
or Series D Convertible Preferred Stock, but not Common Stock, being listed with
a national securities exchange or quoted on the NASDAQ National Market System or
Small Cap System, shall be borne by the Company.

     5.5     Indemnification.

     (a) In the event of any  registration  of any Shares under the Act pursuant
to Article XI of the  Debenture,  the Company will,  to the extent  permitted by
law,  indemnify and hold harmless the seller of such Shares and each underwriter
of such  securities  and each other person,  if any, who controls such seller or
underwriter within the meaning of the Act, against any losses, claims,  damages,
or  liabilities,  joint or  several,  to which  such  seller or  underwriter  or
controlling  person may become subject,  under the Act or otherwise,  insofar as
such losses,  claims,  damages,  or liabilities (or actions in respect  thereof)
arise  out of or are based  upon (i) any  untrue  statement  or  alleged  untrue
statement of any material fact contained,  on the effective date thereof, in any
registration  statement under which such  securities  were registered  under the
Act, any preliminary  prospectus or final prospectus  contained therein,  or any
amendment or  supplement  thereto,  or (ii) any omission or alleged  omission to
state therein a material fact required to be stated therein or necessary to make
the  statements  therein not  misleading;  and the Company will  reimburse  such
seller and each such underwriter and each such controlling  person for any legal
or  any  other  expenses   reasonably   incurred  by  them  in  connection  with
investigating or defending any such loss, claim, damage,  liability,  or action,
provided  that the  Company  shall not be liable in any such case to the  extent
that any such loss,  claim,  damage, or liability arises out of or is based upon
an untrue  statement or alleged untrue statement or omission or alleged omission
made in such  registration  statement,  any such preliminary  prospectus,  final
prospectus,  amendment or supplement  in reliance  upon and in  conformity  with
written information furnished to the Company through an instrument duly executed
by such seller or underwriter specifically for use in the preparation thereof.

     (b) The Company may require,  as a condition to including any Shares in any
registration  statement  filed pursuant to Section 11.03 of the Debenture,  that
the Company  shall have  received  an  undertaking  satisfactory  to it from the
prospective  seller of such Shares and from each underwriter of such Shares,  to
indemnify  and hold  harmless  (in the same manner and to the same extent as set
forth in subdivision  (a) of Section 11.05 of the  Debenture) the Company,  each
director  of the  Company,  each  officer  of the  Company  who shall  sign such
registration  statement  and any  person who  controls  the  Company  within the
meaning  of the Act,  with  respect  to any  statement  or  omission  from  such
registration statement, any preliminary prospectus or final prospectus contained
therein,  or any amendment or supplement  thereto, if such statement or omission
was made in reliance upon and in conformity with written  information  furnished
to the Company through an instrument duly executed by such seller or underwriter
specifically  for  use  in  the  preparation  of  such  registration  statement,
preliminary prospectus, final prospectus, amendment, or supplement.

     (c)  Promptly  after  receipt  by an  indemnified  party of  notice  of the
commencement  of any  action  involving  a claim  referred  to in the  preceding
subdivisions of Section 11.05 of the Debenture,  such indemnified party will, if
a claim in respect  thereof is to be made against an  indemnifying  party,  give
written notice to the latter of the  commencement of such action,  provided that
the failure of any  indemnified  party to give notice as provided  therein shall
not relieve the indemnifying  party of its obligations under the subdivisions of
Section 11.05 of the  Debenture.  In case any such action is brought  against an
indemnified party, the indemnifying party will be entitled to participate in and
to  assume  the  defense  thereof,  jointly  with any other  indemnifying  party
similarly  notified  to the extent  that it may wish,  with  counsel  reasonably
satisfactory to such  indemnified  party, and after notice from the indemnifying
party to such indemnified party of its election so to assume the defense thereof
the  indemnifying  party  will not be liable to such  indemnified  party for any
legal or other expenses  subsequently  incurred by the latter in connection with
the defense thereof.  No indemnifying party, in the defense of any such claim or
litigation, shall, except with the consent of each indemnified party, consent to
entry of any judgment or enter into any settlement  which does not include as an
unconditional  term  thereof  the giving by the  claimant or  plaintiff  to such
indemnified  party of a release  from all  liability in respect to such claim or
litigation.

                               ARTICLE VI
                          AFFIRMATIVE COVENANTS

     6.1 Preferred Shareholders' Consent. The Company shall use its best efforts
to procure  and  deliver to WEDGE by March 31,  1999 the  written  agreement  of
66-2/3%  of the  ownership  interest  of the  Series C  Preferred  Shareholders,
granting  the Company the right to create the Senior  Preferred  Stock.  In this
regard,  the  Company's  Board  of  Directors  shall  solicit  such  consent  by
acknowledging  its  affirmative  support  for  the  creation  of such  class  of
securities  and its approval of WEDGE to convert into such class of  securities.
Notwithstanding  the  obligations  of the Company  required in this Section 6.1,
failure to obtain such consent shall not be deemed an event of default under the
Debenture.

     6.2 Board Seats. So long as (i) the Debenture is outstanding, or (ii) WEDGE
shall own shares of capital stock  representing  10% of the capital stock of the
Company on a fully diluted basis utilizing the "treasury method" as described in
Section  2.3 above,  the Board of  Directors  agrees to support  and cause to be
placed on the ballot at each  election  of  Directors  two names  which shall be
nominees to the Board of Directors ("WEDGE Board Nominees").  Additionally,  the
Company agrees that the Board of Directors shall not contain more than seven (7)
members. The Company shall call a special directors' meeting to create two board
positions to be filled by the WEDGE Board  Nominees prior to the next meeting of
shareholders  for the election of  Directors.  In  furtherance  of the Company's
obligations  under this Section 6.2, certain  shareholders  have agreed to enter
into a limited voting agreement,  the purpose of which is to contractually  bind
those  individuals to vote their shares at each directors'  election in favor of
the WEDGE Board Nominees.  A copy of the Voting Agreement is attached as Exhibit
"D" hereto.

     6.3 Inspection of Property,  Books and Records.  The Company shall (a) keep
proper  books of record and account in which full,  true and correct  entries in
conformity with generally  accepted  accounting  principles shall be made of all
dealings  and  transactions  in relation to its  business  activity,  (b) permit
representatives  of WEDGE to visit  and  inspect  any of its  properties  and to
examine and make abstracts from any of its books and records at their  customary
location  during  normal  business  hours or at such  other  times as WEDGE  may
reasonably request,  and as often as may be reasonably desired for use by WEDGE,
and to discuss the  business,  operations,  properties  and  financial and other
condition  of  the  Company   with  the   Company's   officers  and   employees.
Additionally, the Company will adhere to the requirements of Section 4.01 of the
Debenture by providing  all financial and business  information  and  statements
required therein within the time frames provided.

                                ARTICLE VII
                             NEGATIVE COVENANTS

     7.1 No Cash Dividends.  The Company agrees that it shall not so long as (i)
the Debenture  remains  outstanding or (ii) WEDGE owns shares of preferred stock
representing  at least 10% of the  shares of capital  stock of the  Company on a
fully diluted basis utilizing the "treasury  method" as described in Section 2.3
above, pay any cash dividends or any interest accruals on any equity security or
any debt  security,  excluding  any  Superior  Indebtedness  as  defined  in the
Debenture,  in existence as of the date hereof or created  hereafter  unless and
until the Company's earnings before deduction of interest,  taxes,  depreciation
and  amortization  ("EBITDA")  for the six (6) months ended with the quarter for
the last  quarterly  report  which the  Company is  required to furnish to WEDGE
under  Section  4.01 of the  Debenture  are  more  than  125%  of the  Company's
obligations  for all dividends  and interest due and payable on all  outstanding
securities  of the  Company as of such time.  The Company  agrees that  interest
payments on the  Debenture  shall take  priority in payment  over any  preferred
stock dividends payable to current holders of Series C Preferred Stock.

     7.2 Prohibition  Against Capital  Expenditures.  The Company agrees that so
long as (i) the  Debenture  remains  outstanding  or (ii) WEDGE  owns  shares of
preferred stock representing at least 10% of the capital stock of the Company on
a fully  diluted basis  utilizing the "treasury  method" as described in Section
2.3  above,  the  Company  will not  incur,  or  commit to  incur,  any  capital
expenditures  of any kind or nature in excess of $50,000 without the approval of
the Board of Directors of the Company, and, in addition, the Company agrees that
until the Company has expended the  $2,500,000  in proceeds from the issuance of
the Debenture from the date hereof,  there shall not be any capital expenditures
in excess of $50,000  without the  affirmative  written  consent of WEDGE or its
affiliate  who is then the holder of the  Debenture or any security  convertible
thereto.

     7.3 Reorganization, Stock Dividends, Reclassification, Subdivision or Stock
Issuances. The Company will not (i) enter into a reorganization,  consolidation,
merger,  lease or sale with another entity in connection with the sale, transfer
or conveyance of its Common Stock or assets,  (ii)  subdivide or reclassify  the
outstanding  Common  Stock into a greater or lesser  number of shares,  or (iii)
issue any  additional  shares of its capital  stock,  unless it shall have given
WEDGE at least fifteen (15) days' advance written notice.





<PAGE>



                                  ARTICLE VIII
                  REPRESENTATIONS AND WARRANTIES BY THE COMPANY

     The Company represents and warrants that:

     8.1  Organization  and  Existence,  Etc. The Company is a corporation  duly
organized and validly  existing and in good standing under the laws of the state
of Texas and has all  requisite  corporate  power and  authority to carry on its
business as now  conducted  and  proposed to be  conducted;  the Company has all
requisite  corporate power and authority to enter into this Agreement,  to issue
the Debenture and the shares  issuable upon the conversion  thereof and to carry
out the provisions  and  conditions of this Agreement and of the Debenture.  The
Company is duly  qualified and authorized to do business and is in good standing
as a foreign  corporation  in all states where the  ownership of property or the
nature of the  business  transacted  by the  Company  makes  such  qualification
necessary.  The Company has 25,000,000 authorized shares of its Common Stock and
4,000,000  authorized shares of its preferred stock. As of December 1, 1999, the
Company had 2,253,184 issued and outstanding  shares of Common Stock,  1,115,750
issued and outstanding  shares of preferred stock and 31,944 treasury shares. As
of December 1, 1999,  the Company had granted stock options  which,  if all were
exercised,  would equal 179,831 shares of Common Stock.  As of December 1, 1999,
the Company had issued one or more warrants which, if all are exercised, will in
the  aggregate  equal  1,136,574  shares of Common  Stock.  Additionally,  as of
December 1, 1999,  excluding  the shares of Common Stock to be received by WEDGE
upon its  election to convert to Common  Stock,  there are  2,789,375  shares of
Common Stock to be issued if all existing  preferred stock holders were to elect
to convert their shares to Common Stock.

     8.2  Financial  Statements,  Etc.  The Company has  furnished  to WEDGE the
financial  statements  of the  Company,  including a summary of  operations  and
analysis of retained  earnings and  statements of changes in financial  position
covering the year ended  December 31, 1998,  together with balance  sheets as of
such date,  all of which  statements  have been audited by Grant  Thornton  LLP,
independent  certified public accountants,  along with unaudited  statements for
the quarters  ended March 31, June 30, and  September 30, 1999.  Such  financial
statements  fairly  present the  condition of the Company as at the date thereof
and the results of the  operations  of the Company for such  periods.  There has
been no  material  adverse  change  in the  business,  properties  or  condition
(financial or otherwise) of the Company since September 30, 1999.

     Nothing has come to the  attention  of the  Company  that would cause it to
believe that the  above-referenced  financial  statements contained or contain a
false or  misleading  statement of a material fact or omit to state any material
fact  necessary in order to make the  statement  made in such  material,  in the
light of the circumstances under which they were made, not misleading.  There is
no fact known to the Company  which the Company  has not  disclosed  to WEDGE in
writing prior to the date of this Agreement which materially  adversely  affects
the business, properties or condition (financial or otherwise) of the Company.

     8.3 Business.  The Company is primarily engaged in the domestic geophysical
services  business  principally  through  conducting three  dimensional  ("3-D")
seismic  surveys for companies  engaged in the  exploration for oil and gas. The
Company does not presently intend to engage in any other business.

     8.4 Litigation. Except as disclosed in the financial statements referred to
in  Section  8.2,  there is no action,  suit or  proceeding  pending  or, to the
knowledge  of the  Company,  threatened  against the  Company  before any court,
administrative  agency or arbitrator  which might  reasonably be  anticipated to
result in any material  adverse change in the business,  properties or condition
(financial or  otherwise) of the Company or which  questions the validity of any
action taken or to be taken pursuant to or in connection  with this Agreement or
the Debenture.

     8.5 No Material Adverse Contracts,  Etc. The Company is not obligated under
any  contract  or  agreement  or  subject  to any  charter  or  other  corporate
restrictions  which  adversely  affects its  business,  properties  or condition
(financial or  otherwise).  Neither the execution and delivery of this Agreement
or the Debenture,  nor the consummation or the transaction contemplated thereby,
nor  compliance  with the terms and provisions  thereof,  will conflict with, or
result in a breach of, the terms,  conditions or provisions  of, or constitute a
default under,  the charter or bylaws of the Company,  or of any applicable law,
or of any  order,  writ,  injunction  or decree of any court,  administrator  or
arbitrator, or of any agreement or instrument which is applicable to the Company
or under  which the  Company is  obligated  or by which any of its  property  is
bound.

     8.6 Compliance with  Instruments,  Etc. The Company will not, upon the sale
of the  Debenture to WEDGE,  be (i) in default  under any  indenture or material
contract or agreement to which it is a party, (ii) in violation of is charter or
bylaws or of any  applicable  law,  (iii) in default  with respect to any order,
writ, injunction or decree of any court or arbitrator,  or (iv) in default under
any order, license, regulation or demand of any government agency, which default
or violation might  reasonably be anticipated to result in any material  adverse
change in the business,  properties or condition (financial or otherwise) of the
Company.

     8.7 Tax  Returns  and  Liabilities.  The  Company has filed all federal and
state tax  returns  required to be filed and has paid all taxes as shown on such
returns and on all assessments received by it to the extent that such taxes have
become due. In the opinion of the  officers of the  Company,  adequate  accruals
have been set up to cover all  unpaid  taxes.  The  Company  is not aware of any
material liabilities,  contingent or otherwise,  that have not been disclosed in
the financial statements referred to in Section 8.2

     8.8 Permits,  Governmental and Other Approvals. The Company and each of its
employees  possesses such franchises,  licenses,  permits and other authority as
are necessary for the conduct of the Company's  business as now being  conducted
and as  proposed  to be  conducted,  and it is not in  default  under  any  such
franchises,   permits,  licenses  or  other  authority.  No  approval,  consent,
authorization  or other  order of,  and no  designation,  filing,  registration,
qualification  or  recording  with,  any  governmental  authority is required in
connection with the execution, delivery and performance of this Agreement or the
offer, issue and sale of the Debenture to WEDGE.

     8.9  Patents,  Trademarks  and Other  Rights.  The  Company  possesses  all
patents,  patent rights,  trademarks,  trademark rights, trade names, trade name
rights, and copyrights  necessary to conduct its business as now being conducted
and as  proposed  to be  conducted  without  conflict  with any valid  rights of
others.

     8.10 Consents. The Company is not required to obtain any consent,  approval
or waiver by any security holder (debt or equity), creditor, vendor or any other
third  party to enter into the  transactions  contemplated  hereby,  except that
consent described in Section 6.1 herein.

     8.11 Shares to be Fully Paid;  Reservation of Shares. The Company covenants
and  agrees  that all  shares  which may be issued  upon the  conversion  of the
Debenture will, upon issuance,  be fully paid and free from all taxes, liens and
charges with respect to the issue  thereof.  The Company  further  covenants and
agrees that during the period within which the conversion rights  represented by
the Debenture may be exercised,  the Company will at all times have  authorized,
and  reserved  for the  purpose of issue upon  conversion  of the  Debenture,  a
sufficient  number of shares of its Common Stock and preferred  stock into which
the  Debenture  will be  convertible  (all of which shall be newly issued at the
time of such  exercise  and shall not be  treasury  stock)  to  provide  for the
exercise of conversion rights pursuant to this Agreement and the Debenture.

     8.12 Key  Employees.  The Company has no knowledge as to any  intentions of
any key employee or group of key employees to leave the employ of the Company.

     8.13 Survival.  All agreements,  representations  and warranties  contained
herein  shall  survive  the  execution  and  delivery  of  this  Agreement,  any
investigation  at any  time  made by WEDGE or on  WEDGE's  behalf,  the sale and
purchase of the  Debenture,  any  disposition  thereof,  and  conversion  of the
Debenture for shares and any disposition thereof. All statements contained in or
any  certificate  or other  instrument  delivered by or on behalf of the Company
pursuant hereto shall constitute  representations  and warranties by the Company
hereunder.

     8.14 Opinion of Counsel.  The Company  shall deliver an opinion of counsel,
on the date  hereof,  as to the  legal  matters  set  forth in the form of legal
opinion attached hereto as Exhibit "E".

                               ARTICLE IX

                                 DEFAULT

     9.1  Event  of  Default.  As used in this  Agreement,  the term  "Event  of
Default" shall mean any of the following:

     (a) any default of any kind or nature under Section 9.01 of the Debenture;

     (b) any breach of any  representation or warranty contained in Article VIII
herein in any material respect as of the date of issuance or making thereof; or

     (c) any default in the observance of any affirmative  covenant set forth in
Article VI herein or in any  negative  covenant  set forth in Article VII herein
which is not remedied within 30 days after written notice thereof to the Company
by WEDGE.

     9.2 Default  Remedies.  Upon the  occurrence of an Event of Default,  WEDGE
shall be entitled to enforce all rights and remedies provided in Section 9.02 of
the  Debenture,  in addition to all other rights and remedies it may be entitled
to at equity or under law.

                                   ARTICLE X

                                 MISCELLANEOUS

     10.1 Conflict of  Agreement.  The parties agree that in the event the terms
of this Agreement shall conflict with the terms of the Debenture,  the Debenture
shall govern.

     10.2 Counterparts.  This Agreement may be executed in several counterparts,
each of which shall be an original and all of which  together  shall  constitute
one agreement.

     10.3 Amendments. This Agreement may be amended, modified or terminated only
by a written instrument signed by the parties hereto.

     10.4 Governing Law. This Agreement shall in all respects be governed by and
shall be construed in accordance with the laws of the State of Texas.

     10.5  Severability.  If any provision or part thereof of this  Agreement is
found  to be  prohibited,  unenforceable  or  invalid  under  the  laws  of  any
jurisdiction,  the  provision or part thereof shall be  ineffective  only to the
extent of such prohibition,  unenforceability or invalidity under the applicable
law without  effecting the  enforceability  or validity of such provision in any
other  jurisdiction and without  invalidating the remainder of such provision or
other provisions in this Agreement.

     10.6 Injunctive  Relief.  The Company  acknowledges that a breach of any of
the provisions  hereof would cause  irreparable harm to WEDGE and agrees that in
the event of any such  threatened  breach WEDGE shall be entitled to  injunctive
relief and that it shall not be required to post any bond in excess of $1,000.

     10.7 Term. Defined terms not defined herein shall have the meaning ascribed
thereto in the Debenture.

     10.8  Notices.  All notices,  requests,  consents and other  communications
hereunder  shall be in  writing  and  shall be  deemed  to have  been  made when
delivered or mailed,  first-class  postage  prepaid,  by certified mail,  return
receipt requested.

          If to WEDGE:

               WEDGE Energy Services, L.L.C.
               1415 Louisiana

               Suite 3000
               Houston, Texas 77002
               Attention: President

               with a copy to:

               WEDGE Group Incorporated
               1415 Louisiana

               Suite 3000
               Houston, Texas 77002
               Attention: General Counsel

               with a copy to:

               Darryl M. Burman, Esq.
               DiCecco, Fant & Burman, L.L.P.
               1900 West Loop South

               Suite 1100
               Houston, Texas 77027

          If to the Company:

               TGC Industries, Inc.
               1304 Summit Avenue

               Suite 2
               Plano, Texas 75074


<PAGE>



               with a copy to:

               Vernon R. Rew, Jr.
               Law, Snakard & Gambill, P.C.
               3200 Bank One Tower
               500 Throckmorton
               Fort Worth, Texas 76102

     10.9  Headings.  The headings of the sections of this  Agreement  have been
inserted  for  convenience  or  reference  only and shall in no way  restrict or
otherwise modify any of the terms or provisions hereof.

     10.10  Costs.  The  Company  has agreed to pay all legal  costs of WEDGE in
connection  with the negotiation and preparation of the Note and this Agreement,
which costs shall not exceed $20,000.

     IN WITNESS  WHEREOF,  the parties have executed this  Agreement on the date
first set forth above.

TGC INDUSTRIES, INC.                    WEDGE ENERGY SERVICES, L.L.C.

By:  /s/ Wayne Whitener                 By:  /s/ Gregory J. Armstrong

     -------------------------               -------------------------------
Name: Wayne Whitener                    Name:  Gregory J. Armstong
Title: President                        Title:  Vice President


<PAGE>















                                   EXHIBIT "A"

                                    DEBENTURE


<PAGE>


                                                                      12/10/99

                            DEBENTURE AGREEMENT

     8 1/2 % Convertible Subordinated Debenture, Series B Due December 1, 2009
                  Original Principal Amount $2,500,000

     THIS DEBENTURE AGREEMENT  (the"Agreement") is made and entered into on this
10th day of December,  1999, by and between  WEDGE Energy  Services,  L.L.C.,  a
Delaware limited liability company ("Holder") and TGC Industries,  Inc., a Texas
corporation (the"Company").

                                   R E C I T A L S

     WHEREAS  the  Company  is  issuing  this  8 1/2%  Convertible  Subordinated
Debenture,  Series B due  December 1, 2009 in the original  principal  amount of
$2,500,000  (the"Debenture" or the"Note")  pursuant to the payment of $2,500,000
cash by Holder to the Company and the Company is paying to Holder all  principal
and accrued  interest on that certain  Advance Note in the  principal  amount of
$300,000,  payable by Company to Holder dated November 1, 1999, and as set forth
in that  certain  Debenture  Purchase  Agreement  of  even  date  herewith  (the
"Purchase Agreement").

     WHEREAS  the  Company  is now  issuing  to the  Holder  and the  Holder  is
receiving such Debenture from the Company; and

     WHEREAS the parties  hereto wish to set forth the terms and  conditions  of
such Debenture;

     NOW,  THEREFORE,  in  consideration  of the  premises  and  of  the  mutual
agreements hereinafter set forth, the parties hereto agree as follows:

                               ARTICLE I

                              DEFINITIONS

     In addition to the terms defined elsewhere in this Agreement, the following
terms shall have the meanings set forth below:

     Section 1.01. Capitalized Lease. The term"Capitalized Lease" shall mean any
lease of real or personal  property  under which the rentals are  required to be
capitalized  for  financial  reporting  purposes in  accordance  with  generally
accepted accounting principles.

     Section 1.02.  Common Stock.  The term"Common  Stock" shall mean the Common
Stock, par value $.30 per share, of the Company.

     Section 1.03.  Conversion  Price.  The conversion price per share of Common
Stock,  Senior  Convertible  Preferred  Stock or Series D Convertible  Preferred
Stock into which the Debenture is  convertible,  which price is $1.15 per share,
as such  conversion  price may be adjusted and  readjusted  from time to time in
accordance with the terms of Section 8.05 hereof.

     Section 1.04.  Event of Default.  The term "Event of Default" shall mean an
Event of Default as defined in Section 9.01 hereof.

     Section  1.05   Indebtedness.   The   term"Indebtedness"   shall  mean  (a)
indebtedness  for money borrowed and deferred payment  obligations  representing
the unpaid purchase price of property or stock, other than normal trade credits,
which would be included in determining  total liabilities shown on the liability
side of a consolidated  balance sheet of the Company and its  Subsidiaries;  (b)
guarantees and  endorsements  of obligations of others,  directly or indirectly,
including  obligations under industrial revenue and pollution control bonds, and
all other repurchase agreements and indebtedness in effect guaranteed through an
agreement,  contingent  or  otherwise,  to  purchase  such  indebtedness,  or to
purchase or sell property,  or to purchase or sell  services,  primarily for the
purpose of enabling the debtor to make payment of the  indebtedness or to assure
the owner of the  indebtedness  against  loss,  or to supply  funds to or in any
manner  invest  in the  debtor,  or  otherwise  (but  excluding  guarantees  and
endorsements  of  notes,  bills  and  checks  made  in the  ordinary  course  of
business); (c) indebtedness secured by any mortgage,  lien, pledge,  conditional
sale  agreement,  title  retention  agreement,  or other  security  interest  or
encumbrance upon property owned by the Company, or its Subsidiaries, even though
such  indebtedness has not been assumed;  and (d) amounts due under  Capitalized
Leases as reflected on the balance sheet.

     Section 1.06. Interest Rate. The term"Interest Rate" shall mean an interest
rate payable on the  Debentures of 8 1/2% per annum and as set forth on the face
of the Debenture.

     Section 1.07. Issuance Date. The term"Issuance Date" shall mean the date of
issuance of the  Debenture of December 10, 1999, as set forth on the face of the
Debenture.

     Section 1.08. Maturity Date. The term"Maturity Date" shall mean December 1,
2009.

     Section  1.09.  Debenture.  The  term"Debenture"  shall mean the  Debenture
issued by the Company and concurrently herewith being acquired by the Holder, in
the form set forth on Exhibit"A"  attached hereto, as originally  executed or as
may from time to time be supplemented  or amended  pursuant to its provisions or
the provisions hereof. If the Holder purchases or otherwise becomes the owner of
more  than  one  Debenture,  the  term"Debentures"  shall  include  all  of  the
Debentures owned by the Holder taken as a whole. The term"Debentures" shall mean
all of the  Debentures  issued by the Company and governed by this Agreement and
other Debenture Agreements of like tenor.

     Section  1.10.   Person.   The  term"Person"   shall  mean  an  individual,
partnership, corporation, trust or unincorporated organization, and a government
or agency or political subdivision thereof.

     Section  1.11.  Senior   Convertible   Preferred  Stock  The  term  "Senior
Convertible  Preferred  Stock" shall mean that  certain  series of 8 1/2% Senior
Convertible  Preferred  Stock  as  described  in  Section  3.1 of  the  Purchase
Agreement.

     Section  1.12.  Series D  Convertible  Preferred  Stock The term  "Series D
Convertible  Preferred  Stock"  shall  mean that  certain  series of 8% Series D
Convertible  Preferred  Stock  as  described  in  Section  3.2 of  the  Purchase
Agreement.

     Section 1.13. Superior Indebtedness.  The term"Superior Indebtedness" shall
mean (a) Funded Debt,  being all  Indebtedness  having a final  maturity of more
than one year, and all guarantees of Indebtedness  extending more than one year,
from  its"date of origin" or which is renewable or  extendable  at the option of
the  obligor  for a period  or  periods  of more  than one year from its date of
origin,  and all amounts due under  Capitalized  Leases reflected on the balance
sheets;  and (b)  Current  Debt,  being  all  unsecured  Indebtedness  for money
borrowed,  payable on demand or having a maturity of not more than one year from
the date of determination (other than current maturities of Funded Debt) and not
extendable or renewable at the option of obligor.

     Section 1.14.  Subsidiary.  The term"Subsidiary" shall mean any corporation
of which more than 80% (by number of votes) of the voting  stock is owned by the
Company or another Subsidiary.

                                 ARTICLE II

                                THE DEBENTURE

     Section  2.01.  Debenture.  This  Debenture is in the  principal  amount of
$2,500,000  and is being  issued by the  Company to the Holder  pursuant  to the
payment of Two Million Five Hundred Thousand Dollars ($2,500,000) cash by Holder
to the Company.  In  connection  therewith,  the Company shall pay to Holder all
principal  and accrued  interest on that certain  Advance Note in the  principal
amount of $300,000, payable by Company to Holder dated November 1, 1999, and the
security  interest in certain vehicles and additions  thereto and  substitutions
therefor  created by that  certain  Security  Agreement  between  the Company as
debtor  and the  Holder as  secured  party  dated  November  1,  1999,  shall be
terminated  and the  collateral  with respect  thereto shall be released and all
title  documents  with  respect to such  vehicles  held by the  Holder  shall be
returned to the Company. The Holder hereby agrees to receive such Debenture from
the Company  pursuant  to the terms of this  Agreement,  and the Company  hereby
agrees to issue, convey,  transfer, and assign to the Holder, the Debenture free
and  clear  of all  liens,  options,  claims,  and  encumbrances  of any kind or
character  whatsoever,  except for applicable transfer  restrictions required by
federal and state  securities  laws.  The Debenture  may have such  notations or
legends as are required by applicable  law. The  Debenture  shall be executed on
behalf of the Company by its president or any vice  president and attested to by
its secretary of any assistant  secretary.  The Debenture  shall recite upon its
face the principal amount of indebtedness  evidenced by the Debenture,  the rate
at which interest is payable on the Debenture, and the terms of repayment.

     Section 2.02.  Acquisition  Price.  If the Debenture is being received from
the Company upon issuance,  the acquisition price for the Debenture shall be the
aggregate  principal amount thereof.  No original issue discount is contemplated
by the issuance of these Debentures.

     Section 2.03. [Intentionally Omitted]

     Section  2.04.  Registration.  The  Debentures  shall be  registered in the
Debenture  records of the  Company as  follows:  The  Company  shall  maintain a
register of the issuance of the  Debentures by recording the issuance  date, the
face amount,  and the name and address of the initial  holder and, upon transfer
in accordance with Article X of this  Agreement,  each transferee of each of the
Debentures  upon the books of the  Company.  The  Company  shall be  entitled to
recognize  the person  registered  in the register as the  exclusive  owner of a
Debenture for the purposes of payment of principal and interest thereon, and the
Company  shall not be bound to  recognize  any  equitable  or other  claim to or
interest in such  Debenture on the part of any other person,  whether or not the
Company has express notice thereof,  except as otherwise  provided by applicable
law.

     Section  2.05.  Interest  on  Debenture.  Interest  shall be payable on the
outstanding  principal amount of the Debenture at the Interest Rate. Interest on
the  Debenture  shall be  calculated  on the basis of a  360-day  year of twelve
30-day months.  Interest shall be calculated  semi-annually as of December 1 and
June 1 of each year from the  Issuance  Date through the last such date prior to
the Maturity Date and on the Maturity Date, and accrued interest as of each such
date  shall be due and  payable  fifteen  calendar  days  after  each such date,
provided that the first such date on which interest shall be calculated and paid
shall be the first such semi-annual date following the original  issuance of the
Debenture.  If the  Company  fails  to pay to the  Holder  any  portion  of cash
interest that has accrued on the principal  amount of the Debenture when payment
is due, such unpaid  portion of accrued  interest  shall continue to be due from
and payable by the Company to the Holder until paid.  Interest  shall be payable
in cash, provided that for each interest payment due and payable through January
1, 2001, the interest payment shall be by payment in kind securities by issuance
of additional Debentures of like tenor as this Debenture with a principal amount
equal to the  amount of the cash  interest  payment  which  would have been paid
("PIK  Interest").  For each  interest  payment due and payable after January 1,
2001,  payment  shall be by cash or by PIK Interest at the election of Holder by
written  notice to the  Company,  provided  that the Company  shall only pay PIK
Interest  and not cash  interest  in the event  the  Company's  earnings  before
deduction of interest, taxes, depreciation and amortization (EBITDA) for the six
(6) months ended with the previous quarter (for the December 1 payment:  the six
(6) months ended  September  30; and for the June 1 payment:  the six (6) months
ended  March 31) are less than one  hundred  twenty-five  percent  (125%) of the
Company's  obligation for such interest  payment and for all other dividends and
interest due and payable on all other  outstanding  securities of the Company as
of such time. The Company hereby agrees that interest  payments on the Debenture
shall  take  priority  over any  preferred  stock  dividends  payable to current
holders of the Company's 8% Series C Convertible Exchangeable Preferred Stock.

     Section 2.06.  Lost or Stolen  Certificates.  In the event the  certificate
representing the Debenture is destroyed,  misplaced, or stolen, the Holder shall
promptly notify the Company of such loss. In its discretion, the Company may, as
a condition  precedent to  reissuing a new  Debenture  certificate,  require the
Holder to do one or more of the following things:

     (a) Deliver a notice to the Company in the form  prescribed  by the Company
requesting the Company to stop transfer of such lost Debenture certificate;

     (b) Execute and deliver to the Company an affidavit  of the facts  covering
the loss of the Debenture certificate; and

     (c) Execute and file any form  required by any state or federal  regulatory
authority in connection with the loss of the Debenture certificate.

After the  Holder has  complied  with such  requirements  as the  Company  deems
necessary and appropriate,  the Company shall cancel the lost certificate in its
register and shall issue a new  Debenture  certificate  to the Holder with terms
and provisions identical to those contained in the lost certificate.

     Section  2.07.  Governmental  Charges.  For any  transfer of a Debenture or
exchange of a Debenture for Debentures of another denomination,  the Company may
require from the Holder the payment of a sum  sufficient to reimburse it for any
stamp tax or other governmental charge incidental thereto.



                                ARTICLE III

                         PREPAYMENT OF DEBENTURES

     Section 3.01.  Optional  Prepayment of Debentures.  The Company may, at any
time after  December  1, 2001,  prepay  the  Debentures  in whole or in part (in
amounts  of not less than  $50,000)  by  payment of one  hundred  fifty-two  and
174/1000  percent  (152.174%)  of  the  outstanding   principal  amount  of  the
Debentures,  or  portion  thereof to be  prepaid,  and  payment  of the  accrued
interest thereon to the date of prepayment.  Except as set forth in this Article
III, the Company may not prepay the Debentures prior to maturity.

     Section 3.02. Notice of Prepayments.  The Company shall give written notice
of any  prepayment  of the  Debentures  pursuant to Section 3.01, to each holder
thereof  not less than thirty (30) days nor more than sixty (60) days before the
date fixed for such  optional  prepayment.  Such notice  shall  specify (i) such
date, and (ii) the principal amount of the holder's Debentures to be prepaid and
the  aggregate  principal  amount of all  Debentures  to be  prepaid.  Notice of
prepayment  having been so given,  one hundred  fifty-two  and 174/1000  percent
(152.174%) of the aggregate principal amount of the Debentures specified in such
notice,  and the accrued  interest  thereon  shall become due and payable on the
prepayment date.

     Section 3.03.  Allocation of  Prepayments.  All partial  prepayments of the
Debentures  shall be applied on all  outstanding  Debentures  then being prepaid
ratably in accordance with the unpaid principal amounts of the Debentures.

     Section  3.04.  Merger or Sale. In the event of the  consolidation  with or
merger of the Company  with or into  another  corporation  or entity,  or in the
event of the sale,  lease or conveyance to another  corporation or entity of the
assets of the Company as an entirety or substantially as an entirety, then, upon
the written  request of any Holder of the  Debentures,  the Company shall prepay
such Holder's  Debentures in whole by payment of one hundred  percent  (100%) of
the  principal  amount of the  Debentures  and payment of the  accrued  interest
thereon to the date of  prepayment,  within  thirty  (30) days of the  Company's
receipt of such written request.

                               ARTICLE IV

                FINANCIAL STATEMENTS AND OTHER INFORMATION.

     Section 4.01.  Financial and Business  Information.  The Company  agrees to
furnish to you so long as you or your  nominee  are the holder of any  Debenture
and to each other holder of the then outstanding Debentures:

     (a) Quarterly  Statements.  Within 45 days after the end of each  quarterly
fiscal  period  (except the last) in each fiscal year of the Company,  duplicate
copies of:

     (1)  consolidated  balance  sheets of the  Company  as of the close of such
period,

     (2) consolidated  statements of income and retained earnings and changes in
financial  position of the Company for such quarterly  fiscal period and for the
portion of the fiscal year ending with such period, and

          (3)  consolidated  statements  of cash  flows of the  Company  for the
portion of the fiscal year ending with such period.

in each case (except (a)(1) above) setting forth in comparative form the figures
for the  corresponding  period of the preceding  fiscal year,  all in reasonable
detail and  certified  as having been  prepared  in  accordance  with  generally
accepted accounting  principles,  but subject to changes resulting from year-end
adjustments, by an authorized financial officer of the Company.

     (b) Annual Statements. As soon as available and in any event within 90 days
after the close of each fiscal year of the Company, duplicate copies of:

          (1) audited consolidated balance sheets of the Company as of the close
of such fiscal year, and

     (2) audited  consolidated  statements  of income and retained  earnings and
changes in financial position of the Company for such fiscal year.

In each case setting  forth in  comparative  form the figures for the  preceding
fiscal year, all in reasonable  detail and  accompanied,  in the case of audited
statements, by an opinion thereon of a firm of independent public accountants of
recognized  national  standing  selected  by the  Company to the effect that the
audited  financial  statements  have been prepared in accordance  with generally
accepted accounting principals consistently applied (except for changes in which
such  accountants  concur) and that the audit by such  accountants in connection
with financial  statements has been made in accordance  with generally  accepted
auditing standards.

     The financial statements delivered pursuant to paragraphs (a) and (b) above
shall  set  forth  the  amounts  charged  in each of the  periods  involved  for
depreciation and amortization, and for interest expense.

     (c) Audit Reports.  Promptly upon receipt thereof, one copy of each interim
or special audit made by independent accountants of the books of the Company.

     (d) SEC and Other Reports. Promptly upon their becoming available, one copy
of each  financial  statement,  report,  notice or proxy  statement  sent by the
Company to stockholders  generally, of each Form 8-K, 10-KSB, and 10-QSB, or any
successor  forms,  and any  registration  statement or  prospectus  filed by the
Company with any securities exchange or with the Securities Exchange Commission,
and of all press releases and other  statements made available  generally by the
Company to the public  concerning  material  developments in the business of the
Company.

     (e) Together with each set of quarterly  statements  and annual  statements
pursuant to paragraphs (a) and (b) above, a certificate of an executive  officer
of the Company that such financial  statements are true and correct and that the
Company is not then in default under the terms of this Debenture.

                               ARTICLE V

              REPRESENTATIONS AND WARRANTIES OF THE COMPANY

     The Company hereby represents and warrants to Holder as follows:

     Section 5.01.  Corporate  Organization.  The Company is a corporation  duly
organized and validly  existing and in good standing under the laws of the State
of Texas and has all  requisite  corporate  power and  authority to carry on its
business as now  conducted  and  proposed to be  conducted;  the Company has all
requisite  corporate power and authority to enter into this Agreement,  to issue
the Debenture and the shares  issuable upon the conversion  thereof and to carry
out the provisions  and  conditions of this Agreement and of the Debenture.  The
Company is duly  qualified and authorized to do business and is in good standing
as a foreign  corporation  in all states where the  ownership of property or the
nature of the  business  transacted  by the  Company  makes  such  qualification
necessary.  The Company has 25,000,000 authorized shares of its Common Stock and
4,000,000  authorized shares of its preferred stock. As of December 1, 1999, the
Company had 2,253,184 issued and outstanding  shares of Common Stock,  1,115,750
issued and outstanding  shares of preferred stock and 31,944 treasury shares. As
of December 1, 1999,  the Company had granted stock options  which,  if all were
exercised,  would equal 179,831 shares of Common Stock.  As of December 1, 1999,
the Company had issued one or more warrants which, if all are exercised, will in
the  aggregate  equal  1,136,574  shares of Common  Stock.  Additionally,  as of
December 1, 1999,  excluding  the shares of Common Stock to be received by WEDGE
upon its  election to convert to Common  Stock,  there are  2,789,375  shares of
Common Stock to be issued if all existing  preferred stock holders were to elect
to convert their shares to Common Stock.

     Section 5.02.  Corporate  Power.  The Company has all  requisite  power and
authority to enter into this Agreement,  to issue,  sell,  convey,  assign,  and
transfer the Debenture to the Holder, to own, operate,  and lease its properties
and other  assets and to carry on its  business  as now being  conducted  in the
place or places  where such  properties  or other assets are now owned or leased
and  such  business  is  now   conducted.   No  provision  of  the  Articles  of
Incorporation  or Bylaws of the Company would  preclude any of the  transactions
contemplated by this Agreement.

     Section 5.03. Corporate Authorization.  The execution of this Agreement and
the  consummation  of the  transactions  contemplated  hereunder  have been duly
approved by all necessary corporate action of the Company.

     Section 5.04.  Debenture.  The Debenture  deliverable by the Company to the
Holder  hereunder  will be duly  authorized  and  issued,  free and clear of all
liens,  options,  claims, and encumbrances of any kind or character  whatsoever,
except for  applicable  transfer  restrictions  required  by  federal  and state
securities laws.

     Section 5.05. Compliance with Material Agreements.  The Company is not, and
upon the issuance of the  Debenture to the Holder,  will not be in default under
any material  contract or agreement to which it is a party,  which default might
reasonably  be  anticipated  to result  in any  material  adverse  change in the
business,  properties or condition  (financial or otherwise) of the Company.  So
long as no Event of Default  (as defined  herein)  shall have  occurred,  and be
continuing  with respect to the  Debenture,  the Company may pay dividends  with
respect to its equity securities in accordance with the terms and rights of such
securities.

                               ARTICLE VI

               REPRESENTATIONS AND WARRANTIES OF HOLDER

     The Holder hereby represents and warrants to Company:

     Section 6.01.  Power and Authority.  The Holder has all requisite power and
authority  to enter  into  this  Agreement  and to  acquire  the  Debenture.  No
provision  of  the  Articles  of  Incorporation,   Bylaws,  or  other  governing
instruments of the Holder would preclude any of the transactions contemplated by
this Agreement.

     Section  6.02.  Authorization.  The  execution  of this  Agreement  and the
consummation of the transactions  contemplated herein have been duly approved by
all necessary action, corporate and otherwise, of the Holder.

     Section  6.03.  Investment  Intent.  The Holder is acquiring  the Debenture
solely for its own account  and not with a view to, or for resale in  connection
with, any  distribution  or public offering  thereof,  within the meaning of any
applicable securities laws and regulations.

                              ARTICLE VII

                             SUBORDINATION

     Section 7.01.  Debentures Subordinated to Superior Indebtedness.

Anything in this  Agreement or the  Debentures to the contrary  notwithstanding,
the  indebtedness   evidenced  by  the  Debentures  (such   indebtedness   being
hereinafter  referred to as Subordinated  Indebtedness) shall be subordinate and
junior in right of  payment,  to the extent and in the  manner  hereinafter  set
forth,  to (but only to) all Superior  Indebtedness  (as defined  herein) of the
Company.

     Section 7.02.  Payments on Subordinated Indebtedness.

     (a) So long as no default or event of default  shall have  occurred  and be
continuing  with respect to any Superior  Indebtedness  under the terms thereof,
the Company will pay the principal and interest on all Subordinated Indebtedness
according to the terms thereof.

     (b) During the  continuance  of any default  with  respect to any  Superior
Indebtedness under the terms thereof, including, without limitation, any default
in the payment of either principal or interest on any Superior Indebtedness,  no
payment of  principal,  premium or  interest  shall be made on the  Subordinated
Indebtedness,  if either (i) notice of such  default in writing or by  facsimile
has been  given  to the  Company  by the  holder  or  holders  of such  Superior
Indebtedness;  or (ii) judicial  proceedings shall be pending in respect of such
default.

     Section  7.03.  Insolvency,  etc.  In  the  event  of (a)  any  insolvency,
bankruptcy,    receivership,    liquidation,    reorganization,    readjustment,
composition,  or  other  similar  proceeding  relating  to  the  Company  or its
property,  (b)  any  proceeding  for  the  liquidation,  dissolution,  or  other
winding-up  of  the  Company,  voluntary  or  involuntary,  and  whether  or not
involving  insolvency  or  bankruptcy  proceedings,  (c) any  assignment  by the
Company  for  the  benefit  of  creditors,  or (d) any  distribution,  division,
marshaling,  or application of any of the properties or assets of the Company or
the proceeds thereof to creditors,  voluntary or involuntary, and whether or not
involving legal proceedings, then and in such event:

     (i) all Superior  Indebtedness  shall first be paid in full  (including all
principal,  premium, if any, and interest, including interest accruing after the
commencement of any such  proceeding)  before any payment or distribution of any
character, whether in cash, securities, or other property (other than securities
of the Company or any other corporation provided for by a plan of reorganization
or readjustment or similar plan, the payment of which is subordinated,  at least
to the  extent  provided  in this  Article  VII  with  respect  to  Subordinated
Indebtedness,   to  the  payment  of  all  Superior  Indebtedness  at  the  time
outstanding and to any securities issued in respect thereof under any such plan)
is made in respect of any Subordinated Indebtedness;

               (ii) all  principal  and  premium,  if any,  and  interest on the
Subordinated  Indebtedness  shall  forthwith  become  due and  payable,  and any
payment or distribution of any character,  whether in cash, securities, or other
property (other than securities of the Company or any other corporation provided
for by a plan of  reorganization or readjustment or similar plan, the payment of
which is subordinated,  at least to the extent provided in this Article VII with
respect  to   Subordinated   Indebtedness,   to  the  payment  of  all  Superior
Indebtedness  at the time  outstanding  and to any securities  issued in respect
thereof under any such plan) which would otherwise (but for the terms hereof) be
payable or deliverable  in respect of any  Subordinated  Indebtedness,  shall be
paid or delivered  directly to the holders of the Superior  Indebtedness,  until
all  Superior  Indebtedness  shall  have been paid in full,  the  holders of the
Subordinated   Indebtedness  at  the  time  outstanding  irrevocably  authorize,
empower, and direct all receivers, trustees, liquidators,  conservators,  fiscal
agents,  and others having authority in the premises to effect all such payments
and deliveries;

               (iii) each holder of the  Subordinated  Indebtedness  at the time
outstanding  irrevocably  authorizes  and  empowers  each holder of the Superior
Indebtedness or such holder's  representative to demand,  sue for, collect,  and
receive such holder's ratable share of all such payments and  distributions  and
to receipt therefor, and to file and prove all claims therefor and take all such
other  action,  in the name of such holder or  otherwise,  as such holder of the
Superior  Indebtedness  or such  holder's  representative  may  determine  to be
necessary or appropriate for the enforcement of this Section 7.03; and

               (iv) the holders of the Subordinated  Indebtedness  shall execute
and  deliver  to each  holder  of the  Superior  Indebtedness  or such  holder's
representative all such further instruments  confirming the above authorization,
and all such powers of  attorney,  proofs of claim,  assignments  of claim,  and
other  instruments,  and shall take all such other action as may be requested by
such holder of the Superior  Indebtedness  or such  holder's  representative  to
enforce all claims upon or in respect of the Subordinated Indebtedness.

For all purposes of this Agreement, Superior Indebtedness shall not be deemed to
have been paid in full unless the holders thereof shall have received cash equal
to the amount of  principal,  premium,  if any,  and  interest in respect of all
Superior Indebtedness at the time outstanding, and in case there are two or more
holders of the Superior  Indebtedness any payment or distribution required to be
paid or delivered to the holders of the Superior  Indebtedness  shall be paid or
delivered to such holders ratably according to the respective  aggregate amounts
remaining unpaid on the Superior Indebtedness of such holders.

     Section  7.04.  Payments  and  Distributions  Received.  If any  payment or
distribution of any character (whether in cash,  securities,  or other property)
or any  security  shall be  received  by any  holder of any of the  Subordinated
Indebtedness  in  contravention  of any of the terms of this  Article  VII,  and
except  as  permitted  by  Section  7.03  or  Section  7.06,   such  payment  or
distribution or security shall be held in trust for the benefit of, and shall be
paid  over  or  delivered  and  transferred  to,  the  holders  of the  Superior
Indebtedness  for  application  to  the  payment  of all  Superior  Indebtedness
remaining unpaid, to the extent necessary to pay all such Superior  Indebtedness
in full.  In the event of the  failure of any holder of any of the  Subordinated
Indebtedness  to endorse or assign any such payment,  distribution  or security,
any holder of the  Superior  Indebtedness  or such  holder's  representative  is
hereby irrevocably authorized to endorse or assign the same.

     Section 7.05.  Subrogation.  In the event that cash,  securities,  or other
property  otherwise  payable and deliverable to the holders of the  Subordinated
Indebtedness shall have been applied pursuant to Section 7.03 or Section 7.04 to
the payment of Superior  Indebtedness  in full,  then and in each such case, the
holders of the  Subordinated  Indebtedness  shall be subrogated to any rights of
any  holders  of  Superior   Indebtedness   to  receive   further   payments  or
distributions in respect of or applicable to the Superior Indebtedness.

     Section  7.06.  Acceleration  of  Subordinated  Indebtedness.  In case  any
Subordinated  Indebtedness is declared due and payable because of the occurrence
of an Event of Default  with  respect  to the  Subordinated  Indebtedness  under
circumstances when the terms of Section 7.03 are not applicable,  the holders of
such  Subordinated  Indebtedness  shall not be  entitled  to receive  payment or
distribution  in respect  thereof  until all Superior  Indebtedness  at the time
outstanding shall have been paid in full;  provided,  however,  that, so long as
such Event of Default  does not  constitute  a default or event of default  with
respect  to  any  Superior   Indebtedness,   the  holders  of  the  Subordinated
Indebtedness  shall  continue to be  entitled  to receive  (i) current  interest
payments,  (ii) regularly  scheduled  prepayments  pursuant to Section 3.01, and
(iii) payments due at the stated maturity, notwithstanding such declaration.

     Section 7.07. Notice. In the event that any Subordinated Indebtedness shall
become due and  payable  before its  expressed  maturity on demand of the holder
thereof as the result of the  occurrence  of a default or event of default,  the
Company will give prompt  notice in writing of such  happening to each holder of
Superior Indebtedness.

     Section 7.08.  Subordination  Not Affected,  etc. The terms of this Article
VII, the  subordination  effected  hereby,  and the rights of the holders of the
Superior  Indebtedness shall not be affected by (a) any amendment of or addition
or  supplement  to any  Superior  Indebtedness  or any  instrument  or agreement
relating  thereto,  (b) any exercise or  non-exercise  of any right,  power,  or
remedy under or in respect of any Superior  Indebtedness  or any  instrument  or
agreement relating thereto,  or (c) any waiver,  consent,  release,  indulgence,
extension, renewal, modification,  delay, or other action, inaction or omission,
in respect of any Superior  Indebtedness or any instrument or agreement relating
thereto or any security therefor or guaranty thereof,  whether or not any holder
of any  Subordinated  Indebtedness  shall have had notice or knowledge of any of
the foregoing.  In addition,  in the event that any holder or prospective holder
of Superior Indebtedness  reasonably requires a modification or amendment of the
terms of this Article VII with respect to the  subordination of the Subordinated
Indebtedness, the Holder agrees to execute any such modification or amendment to
this Article VII with respect thereto.

     Section  7.09.  Obligations  Unimpaired.  No  present  or future  holder of
Superior  Indebtedness shall be prejudiced in the right to enforce subordination
of the Subordinated Indebtedness by any act or failure to act on the part of the
Company.  The  provisions  of this  Article  VII are solely  for the  purpose of
defining the relative rights of the holders of Superior  Indebtedness on the one
hand and the holders of Subordinated Indebtedness on the other hand, and nothing
in this  Article  VII shall (a) impair as between  the Company and the holder of
any  Subordinated   Indebtedness  the  obligation  of  the  Company,   which  is
unconditional and absolute, to pay to the holder thereof the principal, premium,
if any,  and  interest  thereon in  accordance  with the terms  thereof,  or (b)
prevent the holder of any Subordinated Indebtedness from exercising all remedies
otherwise  permitted  by  applicable  law under this  Agreement,  subject to the
rights, if any, under this Article VII of the holders of Superior  Indebtedness.

     Section 7.10. Securities Subordinate to Debenture. All equity securities of
the Company shall be subordinate and junior in right of payment as to dividends,
and on  liquidation,  to the rights of the Debenture to payment of principal and
interest and on liquidation.


                            ARTICLE VIII

                      CONVERSION OF DEBENTURES

     Section 8.01.  Conversion  Privilege.  The unpaid  principal  amount of any
Debenture or any portion thereof may, at the election of the holder thereof,  at
any time after the date of such Debenture be converted into (a) shares of Common
Stock at the  conversion  price  per  share of Common  Stock of One  Dollar  and
Fifteen Cents ($1.15) or (b) shares of Senior  Convertible  Preferred  Stock, at
the conversion price per share of such Senior Convertible Preferred Stock of One
Dollar and Fifteen Cents ($1.15),  provided that if the holders of the Company's
8% Series C  Convertible  Exchangeable  Preferred  Stock  ("Series  C  Preferred
Stock") do not  provide  the  necessary  waivers  under the terms  thereof  with
respect to the  issuance of the Senior  Convertible  Preferred  Stock,  then the
Debenture  at the  Holders'  option  may be  converted  into  shares of Series D
Convertible  Preferred  Stock with terms which are pari passu with the Company's
Series C Preferred  Stock, or any  outstanding  series of preferred stock of the
Company with rights and terms  superior  thereto,  at the  conversion  price per
share of Series D  Convertible  Preferred  Stock of One Dollar and Fifteen Cents
($1.15),  further provided that, in any event, such Senior Convertible Preferred
Stock or Series D  Convertible  Preferred  Stock  issued  to the  Holder on such
conversion shall itself have conversion rights into shares of Common Stock which
provide that each share of preferred stock shall be initially  convertible  into
one (1) share of Common  Stock,  as such  conversion  price may be adjusted  and
readjusted  from time to time in  accordance  with  Section  8.05  hereof  (such
conversion price, as so adjusted and readjusted and in effect at any time, being
herein  called  the  "Conversion  Price"),  into the  number  of fully  paid and
non-assessable  shares of Common Stock  determined by dividing (x) the aggregate
principal  amount of the  Debentures  to be so converted  by (y) the  Conversion
Price in effect at the time of such conversion.

     Section 8.02.  Manner of Conversion; Partial Conversion, etc.

     (a) Any  Debenture  may be  converted  in  whole  or in part by the  holder
thereof by  surrender  of such  Debenture,  accompanied  by a written  statement
designating  the principal  amount of such Debenture to be converted and stating
the name and  address  of the person in whose  name  certificates  for shares of
Common Stock are to be registered,  at the office of the Company specified in or
pursuant to Section 15.01. Upon any such partial conversion of a Debenture,  the
Company at its expense will forthwith  issue and deliver to or upon the order of
the holder  thereof a new Debenture or  Debentures in principal  amount equal to
the unpaid and unconverted principal amount of such surrendered Debenture,  such
new  Debenture or  Debentures  to be dated and to bear interest from the date to
which  interest has been paid on such  surrendered  Debenture.  Each  conversion
shall be deemed to have been effected as of the close of business on the date on
which such Debenture shall have been so surrendered to such office,  and at such
time the rights of the holder of such Debenture as such shall,  to the extent of
the principal  amount  thereof  converted,  cease,  and the person or persons in
whose name or names any certificate or  certificates  for shares of Common Stock
shall be issuable upon such conversion shall be deemed to have become the holder
or holders of record thereof.

     (b) The Company  shall pay all cash interest on any Debenture or portion of
any Debenture surrendered for conversion to the date of such conversion.

     Section 8.03.  Delivery of Stock  Certificates.  As promptly as practicable
after  the  conversion  of any  Debenture  in full or in part,  and in any event
within 20 days thereafter,  the Company at its expense (including the payment by
it of any  applicable  issue taxes) will issue and deliver to the holder of such
Debenture,  or as such holder  (upon  payment by such  holder of any  applicable
transfer taxes) may direct, a certificate or certificates for the number of full
and fractional shares of Common Stock issuable upon such conversion.

     Section 8.04. Shares to be Fully Paid; Reservation of Shares.

The Company  covenants  and agrees that all shares of Common  Stock which may be
issued upon conversion of the Debentures will, upon issuance,  be fully paid and
non-assessable  and free from all taxes,  liens, and charges with respect to the
issue thereof; and without limiting the generality of the foregoing, the Company
covenants  and agrees that it will from time to time take all such action as may
be requisite to assure that the par value (if any) per share of the Common Stock
is at all times  equal to or less  than the then  effective  purchase  price per
share of the Common  Stock  issuable  upon  conversion  of the  Debentures.  The
Company  further  covenants  and agrees that the Company  will at all times have
authorized,  and  reserved  for the  purpose  of  issue  or  transfer  upon  the
conversion of the Debentures,  a sufficient number of shares of its Common Stock
to provide for the conversion of the Debentures.

     Section 8.05.  Conversion Price Adjustments.  The Conversion Price shall be
subject to adjustment from time to time as follows:

     (a) Stock Dividends,  Subdivisions,  Reclassifications or Combinations.  If
the  Corporation  shall (i)  declare a dividend  or make a  distribution  on its
Common Stock in shares of its Common Stock,  (ii)  subdivide or  reclassify  the
outstanding  shares of Common  Stock into a greater  number of shares,  or (iii)
combine or  reclassify  the  outstanding  Common Stock into a smaller  number of
shares,  the Conversion  Price in effect at the time of the record date for such
dividend or distribution or the effective date of such subdivision,  combination
or reclassification shall be proportionately  adjusted so that the holder of any
Debentures  surrendered  for  conversion  after such date shall be  entitled  to
receive  the number of shares of Common  Stock which he would have owned or been
entitled to receive had such Debentures been converted immediately prior to such
date. Successive  adjustments in the Conversion Ratio shall be made whenever any
event specified above shall occur.

     (b) Other  Distributions.  In case the Corporation  shall fix a record date
for the making of a  distribution  to all holders of shares of its Common  Stock
(i) of shares of any class other than its Common  Stock or (ii) of  evidences of
indebtedness of the Corporation or any Subsidiary or (iii) of assets  (excluding
cash dividends or distributions,  and dividends or distributions  referred to in
subparagraph 8.05(a) above), or (iv) of rights or warrants, in each such case of
(i) through (iv) the Conversion Price in effect  immediately prior thereto shall
be immediately thereafter proportionately adjusted for such distribution so that
the holder of Debentures  would be entitled to receive the fair market value (as
determined by the Board of Directors, whose determination in good faith shall be
conclusive)  of what a Holder  would  have been  entitled  to  receive  had such
Debentures been converted prior to such  distribution.  Such adjustment shall be
made  successively  whenever such a record date is fixed. In the event that such
distribution  is not so made,  the  Conversion  Price  then in  effect  shall be
readjusted,  effective as of the date when the Board of Directors determines not
to  distribute  such  shares,  evidences  of  indebtedness,  assets,  rights  or
warrants,  as the case may be, to the  Conversion  Price  which would then be in
effect if such record date had not been fixed.

          (c) Consolidation,  Merger, Sale, Lease or Conveyance.  In case of any
consolidation   with  or  merger  of  the  Corporation   with  or  into  another
corporation,  or in case of any sale, lease or conveyance to another corporation
of the assets of the Corporation as an entirety or substantially as an entirety,
the Debentures shall after the date of such consolidation,  merger,  sale, lease
or  conveyance  be  convertible  into the  number  of  shares  of stock or other
securities  or  property  (including  cash) to which the shares of Common  Stock
issuable (at the time of such consolidation,  merger, sale, lease or conveyance)
upon  conversion  of such  Debenture  would  have  been  entitled  to upon  such
consolidation,  merger,  sale,  lease or  conveyance;  and in any such case,  if
necessary,  the  provisions  set forth  herein  with  respect  to the rights and
interests  thereafter of the holders of the  Debentures  shall be  appropriately
adjusted so as to be  applicable,  as nearly as may reasonably be, to any shares
of  stock  or  other  securities  or  property  thereafter  deliverable  on  the
conversion of the Debentures.

     Section 8.06.  Statement  Regarding  Adjustments.  Whenever the  Conversion
Price  shall be adjusted as provided  in Section  8.05,  the  Corporation  shall
forthwith file, at the principal office of the Corporation,  a statement showing
in detail the facts  requiring such  adjustment  and the  Conversion  Price that
shall be in effect after such adjustment, and the Corporation shall also cause a
copy of such statement to be sent by mail, first class postage prepaid,  to each
holder of Debentures,  at its address  appearing on the  Corporation's  records.
Where appropriate, such copy may be given in advance and may be included as part
of a notice required to be mailed under the provisions of Section 8.07.

     Section 8.07. Notice to Holders. In the event the Corporation shall propose
to take any action of the type described in Section 8.05, the Corporation  shall
give  written  notice to each holder of  Debentures,  in the manner set forth in
Section  8.06,  which notice shall specify the record date, if any, with respect
to any such  action and the  approximate  date on which  such  action is to take
place. Such notice shall also set forth such facts with respect thereto as shall
be  reasonably  necessary  to indicate  the effect of such action (to the extent
such effect may be known at the date of such notice) on the Conversion Price and
the number,  kind or class of shares which shall be deliverable  upon conversion
of  Debentures.  In the case of any action  which would  require the fixing of a
record date,  such  written  notice shall be given at least 15 days prior to the
taking of such  action.  Failure  to give such  written  notice,  or any  defect
therein, shall not affect the legality or validity of any such action.

     Section 8.08.  Costs.  The Corporation  shall pay all  documentary,  stamp,
transfer or other  transactional  taxes attributable to the issuance or delivery
of shares of Common Stock upon conversion of any  Debentures;  provided that the
Corporation  shall not be  required  to pay any taxes  which may be  payable  in
respect of any transfer  involved in the issuance or delivery of any certificate
for such  shares in a name other than that of the holder of the  Debentures,  in
respect of which shares are being issued.

                                 ARTICLE IX

                            DEFAULT AND REMEDIES

     Section  9.01.  Event  of  Default.  As  used  in  this  Agreement  and the
accompanying  Debenture,  the  term"Event of Default"  shall mean any one of the
following:

     (a) a default in the payment of interest on any Debenture when due and such
default shall continue for more than fifteen (15) days from such due date;

     (b) a default in the payment of the  principal of Debentures at maturity or
at any date fixed in any notice for prepayment;

     (c) the Company sells or otherwise  disposes of all or substantially all of
its assets to any Person;

     (d) a default in the observance or performance of any covenant or provision
of this  Agreement or of the  Purchase  Agreement  which is not remedied  within
thirty (30) days after  written  notice  thereof to the Company by the holder of
any Debenture;

     (e) any  representation  or warranty  made by the Company  herein or in the
Purchase  Agreement,  or  made  by the  Company  in  any  written  statement  or
certificate  furnished by the Company in connection with the consummation of the
issuance and  delivery of the  Debentures  or furnished by the Company  pursuant
hereto,  is untrue in any  material  respect as of the date of the  issuance  or
making thereof;

     (f) final  judgment or Judgments  for the payment of money  aggregating  in
excess of $250,000 is or are  outstanding  against the Company or any Subsidiary
or against any of the  property or assets of the Company or any  Subsidiary  and
any one of such judgments has remained unpaid,  unvacated,  unbonded or unstayed
by appeal  or  otherwise  for a period of thirty  (30) days from the date of its
entry;

     (g) the  Company  or any  Subsidiary  becomes  insolvent  or  bankrupt,  is
generally not paying its debts as they become due or makes an assignment for the
benefit of  creditors,  or the  Company or any  Subsidiary  causes or suffers an
order for  relief to be entered  with  respect  to it under  applicable  Federal
bankruptcy  law or applies for or consents to the  appointment  of a  custodian,
trustee or receiver for the Company or any  Subsidiary  or for the major part of
the property of the Company or any Subsidiary;

     (h) a custodian,  trustee or receiver is  appointed  for the Company or any
Subsidiary  or for  the  major  part  of the  property  of  the  Company  or any
Subsidiary and is not discharged  within sixty (60) days after such appointment;
or

     (i) bankruptcy,  reorganization,  arrangement or insolvency proceedings, or
other proceedings for relief under any bankruptcy or similar law or laws for the
relief of debtors,  are  instituted by or against the Company or any  Subsidiary
and, if instituted  against the Company or any  Subsidiary,  are consented to or
are not dismissed within sixty (60) days after such institution.

     Section 9.02.  Default Remedies.

     (a) Upon the  occurrence  of an Event of Default,  the Holder may, upon ten
(10) days prior written notice to the Company,  declare the Debenture to be, and
the outstanding principal amount of the Debenture shall thereupon be and become,
forthwith due and payable in cash, together with interest accrued thereon; and

     (b) If an Event of Default  occurs,  the Holder may  proceed to protect and
enforce  its rights by a suit in  equity,  action at law,  or other  appropriate
proceeding,  whether for the specific  performance  of any  agreement  contained
herein  or for an  injunction  against  a  violation  of  any  of the  terms  or
provisions  hereof,  or in aid of the exercise of any power granted herein or by
law.

     Section 9.03. Waiver of Events of Default.  The holders of 51 percent (51%)
of the aggregate principal amount of the Debentures  outstanding may at any time
waive an existing Event of Default and its consequences.

                                   ARTICLE X

                            TRANSFER OF DEBENTURE

     Section  10.01.   Restriction  on  Transfer.   In  addition  to  any  other
restrictions on transfer of the Debenture  imposed by this Article X, the Holder
may  transfer  or assign  his,  her,  or its rights and  obligations  under this
Agreement only in conjunction with the transfer or assignment of the Debenture.

     Section 10.02. Requirements of Transfer. No transfer of the Debenture shall
be valid and effective  unless and until (a) the  transferor  executes a written
assignment of the Debenture or executes a separate power of attorney  indicating
his intent to  transfer  ownership,  (b) the  transferee  executes  a  Debenture
Agreement,  which shall be identical to this  Agreement  except for the Holder's
name and the date of execution, and (c) the transferor delivers written transfer
instructions  (i) signed by the transferor and the transferee,  (ii) stating the
name and mailing and residence address of the transferee,  and (iii) stating the
desired  effective date of such change of ownership.  If the transferee fails to
execute a Debenture Agreement, the transferee's signature on the instructions of
transfer will be deemed to constitute  the  transferee's  assent to the terms of
the Debenture and the Debenture Agreement.

     Section 10.03. Registration of Transfer. Transfer of the Debenture shall be
registered  upon the Company's  register of  Debentures  following the Company's
receipt of all documents necessary to effect transfer in accordance with Section
10.02.  Such documents may be either  personally  delivered by the transferor or
transferee or mailed to the Company in accordance with Section 15.01 hereof.

     Section  10.04.  Effective  Date of  Transfer.  The  effective  date of the
transfer  recorded on the  Company's  register of  Debentures  shall be the date
requested  in the  instructions  of  transfer;  the  effective  date  shall not,
however,  precede the date of the most  recent  payment  date of  interest  with
respect to such Debenture.  In the event such date precedes the date of the most
recent  payment of interest on the  Debenture  or if the desired date is omitted
from the  instructions of transfer,  the Company may in its discretion honor the
transfer,  and, in such case,  the effective date of transfer shall be the first
date at which the Company is in receipt of all of the items  required by Section
10.02 hereof.

     Section  10.05.  Transferee  as Holder.  Upon  completion  of a transfer in
accordance with the provisions provided in this Article X, such Transferee shall
be considered  the Holder as if the  transferee  had been the original  party to
execute this Agreement.

     Section 10.06. Issuance of New Certificates.  Upon a transfer in accordance
with this Article X, and upon  delivery by the  transferor  of his,  her, or its
Debenture certificate representing the Debenture being transferred,  the Company
shall cancel such Debenture certificate and shall issue a new certificate in the
transferee's  name.  Such new  certificate  shall be issued in  accordance  with
Article II hereof,  and its  provisions  will be  identical  to those of the old
Debenture  certificate except as to the Holder's name and the date of execution,
which date on the new  certificate  shall be the same as the effective  transfer
date in accordance with Section 10.04 hereof.

     Section 10.07. Legend on Debenture.  The Debenture shall bear the following
legend:

     "THIS DEBENTURE HAS NOT BEEN  REGISTERED  UNDER THE SECURITIES ACT OF 1933,
AS AMENDED  (THE"ACT") OR THE SECURITIES LAWS OF ANY STATE,  AND HAS BEEN ISSUED
PURSUANT TO EXEMPTIONS FROM SUCH  REGISTRATION AND  QUALIFICATION  REQUIREMENTS.
THIS DEBENTURE MAY NOT BE SOLD, TRANSFERRED,  OR ASSIGNED WITHOUT THE PERMISSION
OF THE ISSUER AND UNLESS THIS DEBENTURE  SHALL HAVE BEEN DULY  REGISTERED  UNDER
THE ACT AND REGISTERED OR QUALIFIED UNDER  APPLICABLE STATE SECURITIES LAWS, OR,
IN  THE  OPINION  OF  COUNSEL  SATISFACTORY  TO  THE  ISSUER,  REGISTRATION  AND
QUALIFICATION OF THE DEBENTURE SHALL NOT BE REQUIRED.  THIS DEBENTURE IS SUBJECT
TO AND ITS TRANSFER IS  RESTRICTED  BY THE TERMS AND  PROVISIONS OF THAT CERTAIN
DEBENTURE AGREEMENT, DATED DECEMBER 1, 1999, EXECUTED BY AND BETWEEN THE COMPANY
AND THE HOLDER OF THIS  DEBENTURE,  A COPY OF WHICH IS ON FILE IN THE OFFICES OF
THE COMPANY."

                                 ARTICLE XI

                             REGISTRATION RIGHTS

     Section 11.01.  Registration  on Request.  Upon the written  request of any
holder or holders of at least fifty-one percent (51%) in the aggregate principal
amount of the Debentures  and/or fifty-one percent (51%) of the shares of Common
Stock, Senior Convertible  Preferred Stock and/or Series D Convertible Preferred
Stock ("Shares") issued upon conversion of such Debentures,  which request shall
state the  intended  method of  disposition  by such holder or holders and shall
request that the Company effect the  registration of all or part of such Shares,
or the Shares issuable upon the conversion of such  Debentures,  or both,  under
the  Securities  Act of 1933, as amended  (the"Act"),  the Company will promptly
give written notice of such requested registration to all holders of outstanding
Debentures  and Shares,  and  thereupon  will use its best efforts to effect the
registration under the Act of:

     (a) the Shares which the Company has been so  requested  to  register,  for
disposition in accordance with the intended method of disposition stated in such
request, and

     (b) all other outstanding Shares, or Shares issuable upon the conversion of
Debentures,  the holders of which shall have made written  request  (stating the
intended  method of  disposition  of such  securities  by such  holders)  to the
Company for  registration  thereof  within thirty (30) days after the receipt of
such written notice from the Company,

all to the extent  requisite to permit the  disposition  (in accordance with the
intended  methods  thereof  as  aforesaid)  by  the  holders  of the  Shares  so
registered  and  to  maintain  such  registration  in  effect  for a  period  of
twenty-four  (24) months;  provided,  that the Company  shall not be required to
register or use its best efforts to effect any  registration of Shares under the
Act  pursuant to this  Section  11.01 more than once.  In the event  that,  as a
result of such registration,  another person with incidental registration rights
granted by the Company  requests  that the Company  include  securities  of such
person in such registration,  such request will not result in a reduction in the
number of securities of the holder or holders of the Debentures and/or Shares to
be included in such registration.

     The Company shall have no obligation to register or use its best efforts to
effect any  registration  of Shares  under the Act  pursuant to this  Article XI
which  would be in  conflict  with the  obligations  of any holder or holders of
Debentures and/or Shares under any confidentiality agreement between such holder
or holders and the Company  entered into in connection  with the offering of the
Debentures to such holder or holders.

     Section 11.02. Incidental Registration. If the Company at any time proposes
to register any of its  securities  under the Act  (otherwise  than  pursuant to
Section  11.01 and other than a  registration  on Form S-8, or the form, if any,
which  supplants  such Form),  it will each such time give written notice to all
holders of outstanding Debentures and Shares of its intention to do so and, upon
the written  request of any such  holder made within  thirty (30) days after the
receipt of any such notice (which  request shall specify the Shares  intended to
be  disposed  of by such  holder and state the  intended  method of  disposition
thereof),  the Company will use its best  efforts to cause all such  outstanding
Shares,  or Shares  issuable upon the conversion of  Debentures,  the holders of
which shall have so requested the registration  thereof,  to be registered under
the Act to the extent  requisite to permit the  disposition  (in accordance with
the intended methods thereof as aforesaid) of the Shares so registered; provided
that, if in the good faith judgment of the managing  underwriter or underwriters
of  a  then  proposed  public  offering  of  the  Company's   securities,   such
registration  of such Shares would  materially and adversely  affect such public
offering,  then in such event the number of Shares  and other  securities  to be
registered  by the Company,  including,  without  limitation,  securities  to be
registered  pursuant to any other registration rights which have been granted by
the  Company,  shall each be  proportionally  reduced to such number as shall be
acceptable to the managing underwriter, subject to Section 11.01.

     Section  11.03.  Registration  Procedures.  If and  whenever the Company is
required  to use its best  efforts  to effect or cause the  registration  of any
Shares  under the Act as provided  in this  Article  XI, the  Company  will,  as
expeditiously as possible:

     (a)  prepare  and  file  with  the  Securities   and  Exchange   Commission
(the"Commission")  a registration  statement with respect to such Shares and use
its best efforts to cause such registration statement to become effective;

     (b) prepare and file with the Commission such amendments and supplements to
such registration  statement and the prospectus used in connection  therewith as
may be necessary to keep such registration  statement  effective for such period
not exceeding a period of twenty-four  (24) months as may be necessary to comply
with the  provisions  of the Act with respect to the  disposition  of all Shares
covered by such registration statement during such period in accordance with the
intended  methods of disposition  by the seller or sellers  thereof set forth in
such registration statement;

     (c)  furnish to each  seller of such  Shares  such number of copies of such
registration  statement and of each such  amendment and  supplement  thereto (in
each case  including  all  exhibits),  such  number of copies of the  prospectus
included in such registration  statement (including each preliminary  prospectus
and, if any seller shall so request, a summary  prospectus),  in conformity with
the  requirements  of the Act,  and such  other  documents,  as such  seller may
reasonably request in order to facilitate the disposition of the Shares owned by
such seller;

     (d) use its best efforts to register or qualify such Shares covered by such
registration  statement  under  such other  securities  or blue sky laws of such
jurisdictions as each seller shall reasonably request,  and do any and all other
acts and things  which may be  reasonably  necessary or advisable to enable such
seller to consummate the disposition in such  jurisdictions  of the Shares owned
by such seller; and

     (e) notify  each  seller of any such  Shares  covered by such  registration
statement,  at any time when a  prospectus  relating  thereto is  required to be
delivered  under the Act within the period  mentioned in subdivision (b) of this
Section 11.03, of the happening of any event as a result of which the prospectus
included in such registration  statement,  as then in effect, includes an untrue
statement of a material  fact or omits to state any material fact required to be
stated therein or necessary to make the statements therein not misleading in the
light of the circumstances then existing,  and at the request of any such seller
prepare and furnish to such seller a reasonable number of copies of a supplement
to or an amendment of such prospectus as may be necessary so that, as thereafter
delivered to the purchasers of such Shares, such prospectus shall not include an
untrue statement of a material fact or omit to state a material fact required to
be stated therein or necessary to make the statements  therein not misleading in
the light of the circumstances then existing.

     Section  11.04.   Registration  Expenses.  All  expenses  incident  to  the
Company's performance of or compliance with this Article XI, including,  without
limitation,  all  registration  and filing fees,  fees and expenses of complying
with securities or blue sky laws,  printing  expenses and fees and disbursements
of counsel for the Company and of independent pubic  accountants,  but excluding
underwriting  commissions and discounts,  the fees of any counsel engaged by the
Holder,  and any  filing  fees  associated  with  shares of  Senior  Convertible
Preferred Stock or Series D Convertible  Preferred  Stock, but not Common Stock,
being  listed  with a  national  securities  exchange  or quoted  on the  NASDAQ
National Market System or Small Cap Market, shall be borne by the Company.

     Section 11.05. Indemnification.

     (a) In the event of any  registration  of any Shares under the Act pursuant
to this Article XI, the Company will, to the extent permitted by law,  indemnify
and hold  harmless  the  seller  of such  Shares  and each  underwriter  of such
securities  and  each  other  person,  if  any,  who  controls  such  seller  or
underwriter within the meaning of the Act, against any losses, claims,  damages,
or  liabilities,  joint or  several,  to which  such  seller or  underwriter  or
controlling  person may become subject,  under the Act or otherwise,  insofar as
such losses,  claims,  damages,  or liabilities (or actions in respect  thereof)
arise  out of or are based  upon (i) any  untrue  statement  or  alleged  untrue
statement of any material fact contained,  on the effective date thereof, in any
registration  statement under which such  securities  were registered  under the
Act, any preliminary  prospectus or final prospectus  contained therein,  or any
amendment or  supplement  thereto,  or (ii) any omission or alleged  omission to
state therein a material fact required to be stated therein or necessary to make
the  statements  therein not  misleading;  and the Company will  reimburse  such
seller and each such underwriter and each such controlling  person for any legal
or  any  other  expenses   reasonably   incurred  by  them  in  connection  with
investigating or defending any such loss, claim, damage,  liability,  or action,
provided  that the  Company  shall not be liable in any such case to the  extent
that any such loss,  claim,  damage, or liability arises out of or is based upon
an untrue  statement or alleged untrue statement or omission or alleged omission
made in such  registration  statement,  any such preliminary  prospectus,  final
prospectus,  amendment or supplement  in reliance  upon and in  conformity  with
written information furnished to the Company through an instrument duly executed
by such seller or underwriter specifically for use in the preparation thereof.

     (b) The Company may require,  as a condition to including any Shares in any
registration  statement filed pursuant to Section 11.03,  that the Company shall
have received an undertaking  satisfactory to it from the prospective  seller of
such Shares and from each  underwriter  of such Shares,  to  indemnify  and hold
harmless (in the same manner and to the same extent as set forth in  subdivision
(a) of this Section  11.05) the  Company,  each  director of the  Company,  each
officer of the Company who shall sign such registration statement and any person
who  controls  the Company  within the meaning of the Act,  with  respect to any
statement  or  omission  from  such  registration  statement,   any  preliminary
prospectus or final prospectus contained therein, or any amendment or supplement
thereto,  if such  statement  or  omission  was  made in  reliance  upon  and in
conformity  with  written  information  furnished  to  the  Company  through  an
instrument duly executed by such seller or underwriter  specifically  for use in
the preparation of such registration statement,  preliminary  prospectus,  final
prospectus, amendment, or supplement.

     (c)  Promptly  after  receipt  by an  indemnified  party of  notice  of the
commencement  of any  action  involving  a claim  referred  to in the  preceding
subdivisions of this Section 11.05,  such indemnified  party will, if a claim in
respect thereof is to be made against an indemnifying party, give written notice
to the latter of the  commencement of such action,  provided that the failure of
any indemnified  party to give notice as provided  therein shall not relieve the
indemnifying  party of its obligations under the preceding  subdivisions of this
Section 11.05. In case any such action is brought against an indemnified  party,
the  indemnifying  party will be  entitled to  participate  in and to assume the
defense thereof, jointly with any other indemnifying party similarly notified to
the  extent  that it may wish,  with  counsel  reasonably  satisfactory  to such
indemnified  party,  and  after  notice  from  the  indemnifying  party  to such
indemnified  party  of  its  election  so to  assume  the  defense  thereof  the
indemnifying party will not be liable to such indemnified party for any legal or
other  expenses  subsequently  incurred  by the  latter in  connection  with the
defense  thereof.  No  indemnifying  party,  in the defense of any such claim or
litigation, shall, except with the consent of each indemnified party, consent to
entry of any judgment or enter into any settlement  which does not include as an
unconditional  term  thereof  the giving by the  claimant or  plaintiff  to such
indemnified  party of a release  from all  liability in respect to such claim or
litigation.

                               ARTICLE XII

                   CONSOLIDATION, MERGER, AND CONVEYANCE

     Section 12.01.  Continuation  of Terms of Agreement.  Nothing  contained in
this Agreement or in the accompanying  Debenture shall prevent any consolidation
or merger of the Company with or into any other  corporation or association,  or
any conveyance of the business, assets, and properties of the Company as a whole
or substantially as a whole, to any other corporation or other entity,  provided
that all  terms and  conditions  of this  Agreement,  including  payment,  to be
observed  and  performed  by the  Company  shall  be  expressly  assumed  by the
successor  entity  formed by or  resulting  from any such merger or to which any
such conveyance shall have been made.

     Section 12.02. Rights of Successor.  If the Company or any successor entity
is consolidated or merged with or into, or shall make a conveyance to, any other
corporation  or other entity,  as permitted and upon the terms  provided in this
Article XII, the entity formed by or resulting from such consolidation or merger
or to which  such  conveyance  shall  have been  made  shall  succeed  to and be
substituted  for the  Company,  with the same force and effect as if it had been
named in, and had executed,  this Agreement,  and shall have and possess and may
exercise,  subject to the terms and conditions of this Agreement, each and every
power, authority, and right herein reserved to or conferred upon the Company.

     Section 12.03. Construction. For every purpose of this Agreement, including
the execution and issuance of the Debenture, the term"Corporation"  includes and
means (unless the context otherwise  requires) not only the corporation that has
executed this Agreement,  but also any such successor  entity in accordance with
the provisions of this Article XII.

     Section  12.04.  Merger or Sale.  In the event of the merger or sale of the
Company as  described  in Section  3.04 of this  Agreement,  the  holders of the
Debentures  shall have the rights to cause the  Debentures  to be prepaid as set
forth in such Section 3.04.


                                 ARTICLE XIII

                              SPECIAL COVENANTS

     So long as,  but only so long as,  the  Debenture  is held by the  original
Holder, WEDGE Energy Services, L.L.C. ("WEDGE") or by an affiliate of WEDGE, the
Company shall be subject to the following special covenants:

     Section 13.01.  Right of Participation The Company grants to Holder a right
of  participation  to participate in any additional  equity  offerings which the
Company may offer,  as set forth in Sections  2.1,  2.2 and 2.3 of the  Purchase
Agreement.

     Section 13.02.  Restriction on Payment of Cash Dividends and Interest.  The
Company  agrees that so long as (i) the Debenture  remains  outstanding  or (ii)
Holder owns shares of preferred stock representing at least 10% of the shares of
capital stock of the Company on a fully  diluted  basis  utilizing the "treasury
method" as described in Section 2.3 of the Purchase Agreement,  it shall not pay
any cash dividends or any interest  accruals on any equity  security or any debt
security,  excluding any Superior  Indebtedness as defined in the Debenture,  in
existence  as of the date  hereof  or  created  hereafter  unless  and until the
Company's  earnings  before  deduction  of  interest,  taxes,  depreciation  and
amortization  ("EBITDA")  for the six (6) months  ended with the quarter for the
last  quarterly  report which the Company is required to furnish to Holder under
Section 4.01 of the Debenture  are more than 125% of the  Company's  obligations
for all dividends and interest due and payable on all outstanding  securities of
the Company as of such time.  The Company  agrees that interest  payments on the
Debenture  shall take  priority in payment over any  preferred  stock  dividends
payable to current holders of Series C Preferred Stock

     Section 13.03. Prohibition Against Capital Expenditures. The Company agrees
that so long as (i) the Debenture remains outstanding or (ii) Holder owns shares
of preferred  stock  representing at least 10% of the shares of capital stock of
the  Company  on a fully  diluted  basis  utilizing  the  "treasury  method"  as
described in Section 2.3 of the Purchase Agreement,  the Company will not incur,
or commit to incur, any capital  expenditures of any kind or nature in excess of
$50,000  without the approval of the Board of Directors of the Company,  and, in
addition, the Company agrees that, until the Company has expended the $2,500,000
in proceeds from the issuance of the Debenture, from the date hereof there shall
be no capital  expenditure in excess of $50,000 without the affirmative  written
consent of WEDGE or its affiliate who is then the Holder of the Debenture or any
security convertible thereto.





<PAGE>



                                 ARTICLE XIV

                                  AMENDMENTS

     Section  14.01.  Without  Consent of  Holder.  The  Company  may amend this
Agreement and the Debenture without the consent of the Holder:

     (a)     To cure any ambiguity, defect, or inconsistency;

     (b) To comply with any  consolidation or merger of the Company with or into
any other corporation, or to comply with any conveyance of the business, assets,
and  properties of the Company as a whole or  substantially  as a whole,  to any
other corporation or other entity,  provided that the corporation  complies with
the terms of Article XII hereof; and

     (c) To make any  change  that does not  adversely  affect the rights of the
Holder.

     Section  14.02.  With  Consent of  Holder.  Subject to the terms of Section
14.01,  the Company may amend this Agreement or the  Debentures  with respect to
any matter  with the  written  consent of the holders of at least 66 2/3 percent
(66  2/3%) of the  aggregate  principal  amount of the  outstanding  Debentures.
However,  without  consent of each  holder  affected,  an  amendment  under this
section may not:

     (a) Reduce the rate of or change the time for  payment of  interest  on any
Debenture;

     (b) Reduce the principal of or change the fixed maturity of any Debenture;

     (c) Make  any  Debenture  convertible  into any  securities  other  than as
described in Section 8.01; or

     (d) Make any change in this Section 14.02.

     Section  14.03.  Revocation  and Effect of Consents.  Until an amendment or
waiver becomes effective, a consent to such amendment or waiver by a holder of a
Debenture is a continuing  consent by such holder and every subsequent holder of
such  Debenture,  even if notation of the consent is not made on any  Debenture.
Any such holder or subsequent holder may, however,  revoke the consent as to his
Debenture if the Company  receives the notice of revocation  before the date the
amendment or waiver becomes effective.  An amendment or waiver becomes effective
in accordance with its terms and thereafter binds every holder of a Debenture.

     Section 14.04. Notation on or Exchange of Debentures. The Company may place
an  appropriate  notation  concerning  an amendment  or waiver on any  Debenture
thereafter issued. The Company in exchange for all outstanding  certificates may
issue new certificates that reflect the amendment or waiver.


                                ARTICLE XV

                         MISCELLANEOUS PROVISIONS

     Section 15.01.  Notices.  Any notice or other communication  required to be
given  pursuant  to this  Agreement  must be in  writing  and  may be  given  by
registered or certified  mail,  and if given by  registered  or certified  mail,
shall be deemed to have been given and received  when a registered  or certified
letter  containing  such notice,  properly  addressed with postage  prepaid,  is
deposited in the United States mail;  and if given  otherwise than by registered
or certified  mail, it shall be deemed to have been given when  delivered to and
received  by the party to whom  addressed.  Such  notices  shall be given to the
parties hereto at the following addresses:

          If to the Company:

               TGC Industries, Inc.
               1304 Summit Avenue

               Suite 2
               Plano, TX  75074

                    With a Copy to:

               Vernon E. Rew, Jr.
               Law, Snakard & Gambill, P.C.
               3200 Bank One Tower
               500 Throckmorton
               Fort Worth, Texas  76102

          If to the Holder:

               WEDGE Energy Services, L.L.C.
               1415 Louisiana

               Suite 3000
               Houston, Texas 77002
               Attention: President

               with a copy to:

               WEDGE Group Incorporated
               1415 Louisiana

               Suite 3000
               Houston, Texas 77002
               Attention: General Counsel

               With a Copy to:

               Darryl M. Burman
               DiCecco, Fant & Burman, L.L.P.
               3D/International Tower
               1900 West Loop South, Suite 1100
               Houston, Texas 77027

     or  addressed  to either  party at such other  address as such party  shall
hereafter  furnish to the other  party in  writing.  The address for any purpose
hereof may be changed at any time and shall be the most recent address furnished
in writing to the other party.

     Section 15.02. Binding Agreement.  This Agreement shall be binding upon and
inure  to  the  benefit  of the  parties  hereto  and  their  respective  heirs,
executors,  administrators,  legal  representatives,  successors,  and  assigns,
except as otherwise expressly provided herein.

     Section 15.03. Severability. If any one or more of the provisions contained
in this  Agreement  should for any  reason be held to be  invalid,  illegal,  or
unenforceable in any respect, such invalidity,  illegality,  or unenforceability
shall not  affect  any  other  provision  hereof,  and this  Agreement  shall be
construed as if such invalid, illegal, or unenforceable provision had never been
contained herein.

     Section 15.04.  No Third Parties.  Except as otherwise  expressly  provided
herein, nothing in this Agreement, expressed or implied, is intended or shall be
construed to confer upon or give to any person,  firm, or corporation other than
the  parties  hereto  and the  holders  from  time  to time of the  accompanying
Debenture any security,  rights, remedies, or claims, legal or equitable,  under
or by  reason  of  this  Agreement,  or  under  or by  reason  of any  covenant,
condition,  or  stipulation  herein  contained;  and this  Agreement and all the
covenants, conditions, and provisions herein contained are and shall be held for
the sole and exclusive  benefit of the parties  hereto and the holders from time
to time of the accompanying Debenture.

     Section  15.05.  Headings.  The  captions  used in  conjunction  with  this
Agreement  are for  convenience  only,  and  shall  not be deemed a part of this
Agreement or used to construe any provision hereof.

     Section 15.06. Survival of Representations,  Warranties, and Covenants. The
representations,  warranties,  and  covenants of the parties  shall  survive the
execution of this  Agreement  and the issuance of the Debenture and shall remain
in full force and effect thereafter.

     Section  15.07.  Entire  Agreement.  This  Agreement  and the  accompanying
Debenture  constitute  the sole and only  agreements  of the parties  hereto and
supersede any prior  understandings  or written or oral  agreements  between the
parties respecting the subject matter within.

     Section   15.08.   Inclusion  of  Debenture.   Reference  is  made  to  the
accompanying  Debenture.  The  provisions  of such  Debenture  shall  be  deemed
incorporated  into this  Agreement for all purposes as though fully set forth on
the face hereof.

     Section  15.09.  Immunities of  Stockholders,  Officers and  Directors.  No
recourse  shall be had for the  payment  of the  principal  of the  accompanying
Debenture  or of the  interest  thereon,  or for  any  claim  based  thereon  or
otherwise in respect thereof, or arising from this Agreement,  against any past,
present,  or future stockholder,  director,  or officer of the Company, as such,
whether  by  virtue  of any  constitution,  statute,  or rule of law,  or by the
enforcement  of any  assessment  or  penalty,  all such  liability  being by the
acceptance of the accompanying Debenture and as part of the consideration of the
issuance  thereof  expressly  waived  and  released  by  the  Holder  and by any
subsequent owners of the Debenture.

     Section 15.10.  Governing  Law. This  Agreement and the Debenture  shall be
governed by and construed in accordance with the laws of the State of Texas.

      IN WITNESS  WHEREOF,  the parties  hereto have caused this Agreement to be
duly executed as of the day and year first above written.

COMPANY:                                HOLDER:

TGC INDUSTRIES, INC.                    WEDGE ENERGY SERVICES, L.L.C.

By: ______________________________          By: ______________________________
   Name:__________________________             Name:__________________________
   Title:_________________________             Title:_________________________


<PAGE>




                                EXHIBIT"A"

                           TGC INDUSTRIES, INC.

            8 1/2% Convertible Subordinated Debenture, Series B
                          Due December 1, 2009

No. 01                                                     December 10, 1999

$2,500,000

     TGC  INDUSTRIES,  INC.,  a  Texas  corporation  (the"Company"),  for  value
received, hereby promises to pay to the order of:

                       WEDGE ENERGY SERVICE, L.L.C.
                         or registered assigns

                      on the 1st day of December, 2009
                        the principal amount of

TWO MILLION FIVE HUNDRED THOUSAND DOLLARS ($2,500,000)

and to pay interest  (computed  on the basis of a 360-day year of twelve  30-day
months) on the principal amount from time to time remaining unpaid hereon at the
rate of eight  and  one-half  (8 1/2%)  per  annum  from the date  hereof  until
maturity,  and in accordance with the terms of that certain Debenture  Agreement
dated December 10, 1999,  calculated and payable semi-annually on December 1 and
June 1 in each year  commencing  with the first such date following the issuance
of this  Debenture,  and at  maturity.  The  Company  agrees to pay  interest on
overdue  principal  (including  any overdue  required or optional  prepayment of
principal),  and (to the extent legally  enforceable) on any overdue installment
of interest, at the rate of ten percent (10%) per annum after maturity,  whether
by acceleration or otherwise, until paid. Both the principal hereof and interest
hereon are payable at the principal  office of the Company in Plano,  Texas,  in
coin or  currency of the United  States of America  which at the time of payment
shall be legal tender for the payment of public and private debts.

     This  Debenture is issued under and pursuant to the terms and provisions of
that certain  Debenture  Agreement dated December 10, 1999,  entered into by the
Company with the original holder therein referred to, and this Debenture and the
holder  hereof is entitled  equally  and  ratably  with the holders of all other
Debentures,  if  any,  outstanding  under  the  Debenture  Agreement  to all the
benefits  provided  for  thereby or  referred  to  therein,  to which  Debenture
Agreement reference is hereby made for the statement thereof.

     This  Debenture and the other  Debentures,  if any,  outstanding  under the
Debenture  Agreement may be declared due prior to their expressed maturity dates
and voluntary  prepayments may be made thereon by the Company all in the events,
on the terms specified in the Debenture Agreement, and in the manner and amounts
as provided in the Debenture Agreement.

     This  Debenture  and  the  indebtedness  evidenced  hereby,  including  the
principal and interest,  shall at all times remain junior and subordinate to any
and all Superior Indebtedness as defined in the Debenture Agreement,  all on the
terms and to the extent more fully set forth in the Debenture Agreement.

     This   Debenture  is  registered  on  the  books  of  the  Company  and  is
transferable  only by surrender  thereof at the principal  office of the Company
duly endorsed or accompanied  by a written  instrument of transfer duly executed
by the registered  holder of this  Debenture or its attorney duly  authorized in
writing. Payment of or on account of principal, premium, if any, and interest of
this  Debenture  shall be made  only to or upon  the  order  in  writing  of the
registered holder.

                                        TGC INDUSTRIES, INC.

                                        By:_____________________________
                                        Name: Wayne Whitener
                                        Title:    President

     THIS DEBENTURE HAS NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS
AMENDED  (THE"ACT")  OR THE  SECURITIES  LAWS OF ANY STATE,  AND HAS BEEN ISSUED
PURSUANT TO EXEMPTIONS FROM SUCH  REGISTRATION AND  QUALIFICATION  REQUIREMENTS.
THIS DEBENTURE MAY NOT BE SOLD, TRANSFERRED,  OR ASSIGNED WITHOUT THE PERMISSION
OF THE ISSUER AND UNLESS THIS DEBENTURE  SHALL HAVE BEEN DULY  REGISTERED  UNDER
THE ACT AND REGISTERED OR QUALIFIED UNDER  APPLICABLE STATE SECURITIES LAWS, OR,
IN  THE  OPINION  OF  COUNSEL  SATISFACTORY  TO  THE  ISSUER,  REGISTRATION  AND
QUALIFICATION OF THE DEBENTURE SHALL NOT BE REQUIRED.  THIS DEBENTURE IS SUBJECT
TO AND ITS TRANSFER IS  RESTRICTED  BY THE TERMS AND  PROVISIONS OF THAT CERTAIN
DEBENTURE AGREEMENT,  DATED AS OF DECEMBER 10, 1999, EXECUTED BY AND BETWEEN THE
COMPANY  AND THE  HOLDER  OF THIS  DEBENTURE,  A COPY OF WHICH IS ON FILE IN THE
OFFICES OF THE COMPANY.





<PAGE>














                                 EXHIBIT "B"

                       Terms of Senior Preferred Stock


<PAGE>



                                                                      12/10/99

                      STATEMENT OF RESOLUTION ESTABLISHING
                    8 1/2% SENIOR CONVERTIBLE PREFERRED STOCK OF

                               TGC INDUSTRIES, INC.

     Pursuant  to  the   provisions  of  Article  2.13  of  the  Texas  Business
Corporation Act, TGC, Industries, Inc., a Texas corporation (the"Corporation" or
the"Company"),  has adopted the following  resolution by all necessary action on
the part of the  Corporation  at a special  meeting of the Board of Directors on
November  30,  1999,  authorizing  the  creation  and  issuance  of a series  of
preferred stock designated as 8 1/2% Senior Convertible Preferred Stock:

     RESOLVED,  that pursuant to the authority  vested in the Board of Directors
of the Corporation by Article 4.b of the  Corporation's  Certificate of Restated
Articles  of  Incorporation,  as  amended,  a series of  preferred  stock of the
Corporation  be, and it is hereby,  created out of the  authorized  but unissued
shares of the capital stock of the  Corporation,  such series to be designated 8
1/2% Senior Convertible  Preferred Stock  (the"Preferred  Stock"), to consist of
2,750,000  shares,  of which the preferences and relative and other rights,  and
the qualifications,  limitations or restrictions thereof,  shall be (in addition
to those  set  forth  in the  Corporation's  Certificate  of  Incorporation,  as
amended) as follows:

     1. Certain  Definitions.  Unless the context otherwise requires,  the terms
defined in this paragraph 1 shall have, for all purposes of this resolution, the
meanings herein specified.

     Common Stock. The term"Common Stock" shall mean all shares now or hereafter
authorized of any class of Common Stock of the  Corporation  and any other stock
of the Corporation, howsoever designated, authorized after the Issue Date, which
has the  right  (subject  always  to prior  rights  of any  class or  series  of
preferred  stock) to participate in the  distribution of the assets and earnings
of the Corporation without limit as to per share amount.

     Conversion Date. The term"Conversion Date" shall have the meaning set forth
in subparagraph 3(e) below.

     Conversion Ratio. The  term"Conversion  Ratio" shall mean the ratio used to
determine the number of shares of Common Stock  deliverable  upon  conversion of
the Preferred Stock,  subject to adjustment in accordance with the provisions of
paragraph 3 below.

     Issue  Date.  The  term"Issue  Date"  shall  mean the date  that  shares of
Preferred Stock are first issued by the Corporation.

     Series C Preferred  Stock.  The term "Series C Preferred  Stock" shall mean
the Corporation's Series C 8% Convertible Exchangeable Preferred Stock.

     Subsidiary. The term"Subsidiary" shall mean any corporation of which shares
of stock  possessing at least a majority of the general voting power in electing
the board of directors are, at the times as of which any  determination is being
made,  owned by the Corporation,  whether directly or indirectly  through one or
more Subsidiaries.

     2. Dividends. The Preferred Stock shall be senior in rights to dividends to
all classes and series of stock of the Corporation, including without limitation
the  Corporation's  Series C Preferred  Stock. In addition,  the Preferred Stock
shall have the following dividend rights:

     (a)  Declaration  of  Dividends.  The holders of shares of Preferred  Stock
shall be entitled to receive cumulative cash dividends,  when and as declared by
the Board of Directors out of funds  legally  available  therefor,  at a rate of
eight and one-half  percent (8 1/2%) per annum and no more  ($0.09775  per share
per  annum  based on the per  share  liquidation  value of  $1.15),  before  any
dividend or distribution in cash or other property (other than dividends payable
in  stock  ranking  junior  to the  Preferred  Stock  as to  dividends  and upon
liquidation,  dissolution  or winding-up) on any class or series of stock of the
Corporation  ranking  junior  to  the  Preferred  Stock  as to  dividends  or on
liquidation,  dissolution  or winding-up  shall be declared or paid or set apart
for payment.

          (b) Payment of Dividends.  Dividends on the  Preferred  Stock shall be
payable, when and as declared by the Board of Directors on December 1 and June 1
of each  year,  commencing  June 1,  2000  (each  such  date  being  hereinafter
individually  a"Dividend  Payment Date" and  collectively  the"Dividend  Payment
Dates"),  except that if such date is a Saturday,  Sunday or legal  holiday then
such dividend shall be payable on the first immediately  preceding  calendar day
which is not a Saturday,  Sunday or legal holiday,  to holders of record as they
appear on the books of the Corporation on such respective  dates,  not exceeding
sixty days  preceding  such  Dividend  Payment Date, as may be determined by the
Board of  Directors  in advance  of the  payment  of each  particular  dividend.
Dividends in arrears may be declared and paid at any time,  without reference to
any regular  Dividend  Payment Date, to holders of record on such date as may be
fixed by the Board of Directors of the Corporation.  Dividends declared and paid
in arrears shall be applied first to the earliest dividend period or periods for
which any  dividends  remain  outstanding.  The amount of dividends  payable per
share of this Series for each dividend  period shall be computed by dividing the
annual rate of eight and one-half percent (8 1/2%) by two (2). Dividends payable
on this  Series  for the  initial  period  and for any  period  less than a full
semi-annual  period  shall be computed on the basis of a 360-day  year of twelve
30-day  months.  Dividends  shall be  payable  in cash,  provided  that for each
dividend  declared and payable  through  December 1, 2000, the dividend  payment
shall be by payment in kind  securities  by  issuance  of  additional  shares of
Preferred  Stock  with a  liquidation  value  equal  to the  amount  of the cash
dividend payment which would have been paid ("PIK Dividend").  For each dividend
payment due and payable after  December 1, 2000,  payment shall be by cash or by
PIK  Dividend  at  the  election  of  the  holders  by  written  notice  to  the
Corporation, provided that the Corporation shall only pay a PIK Dividend and not
a cash  dividend in the event the  Corporation's  earnings  before  deduction of
interest,  taxes,  depreciation and amortization (EBITDA) for the six (6) months
ended with the previous quarter (for the December 1 payment:  the six (6) months
ended  September 30; and for the June 1 payment:  the six (6) months ended March
31) are less than one hundred  twenty-five  percent (125%) of the  Corporation's
obligation  for such dividend  payment and for all other  dividends and interest
due and payable on all other  outstanding  securities of the  Corporation  as of
such time.

     (c) Dividends  Cumulative.  Preferred  Stock shall be cumulative and accrue
from and after the date of original issuance thereof, whether or not declared by
the Board of Directors. Accrued dividends shall not bear interest.

     (d)  Dividend  Restriction.  No cash  dividend may be declared on any other
class or series of stock  ranking  on a parity  with the  Preferred  Stock as to
dividends in respect of any dividend  period  unless there shall also be or have
been declared on the Preferred  Stock like dividends for all periods  coinciding
with or ending  before such  semi-annual  period,  ratably in  proportion to the
respective   annual  dividend  rates  fixed  therefor  and  the  total  dividend
obligation with respect thereto.

     3. Conversion  Rights. The Preferred Stock shall be convertible into Shares
of Common Stock as follows:

     (a)  Conversion  Right.  The holder of any shares of Preferred  Stock shall
have the right,  at such  holder's  option,  at any time to convert  any of such
shares of  Preferred  Stock into fully paid and  nonassessable  shares of Common
Stock  at the  Conversion  Ratio  provided  for in  subparagraph  3(d)  below by
surrendering  shares  of  Preferred  Stock for  conversion  in  accordance  with
subparagraph 3(e) below.

     (b) Continuance of Conversion  Right.  The Conversion Right set forth above
will continue so long as such Preferred Stock is outstanding with respect to any
stock not redeemed in accordance with the terms of paragraph 7.

     (c) Surrender of Shares on Exercise of Conversion  Right. In the event that
any holder of shares of Preferred  Stock  surrenders such shares for conversion,
such  holder  will be issued the number of shares of Common  Stock to which such
holder is entitled pursuant to the provisions of subparagraph 3(d) in the manner
provided for in subparagraph  3(e). The shares of Preferred Stock deemed to have
been surrendered will have the status described in paragraph 11 below.

     (d) Conversion  Ratio. Each share of Preferred Stock may, at the discretion
of the  holder  thereof,  be  converted  into  shares  of  Common  Stock  of the
Corporation  at the  conversion  ratio of one (1) share of Common Stock for each
share  of  Preferred  Stock,  as  such  conversion  ratio  may be  adjusted  and
readjusted from time to time in accordance with  subparagraph  3(g) hereof (such
conversion  ratio,  as adjusted and readjusted and in effect at any time,  being
herein called  the"Conversion  Ratio").  The Conversion  Ratio referred to above
will be subject to adjustment as set forth in subparagraph 3(g).

          (e)  Mechanics  of  Conversion.  The holder of any shares of Preferred
Stock may exercise  the  conversion  right  specified  in  subparagraph  3(a) by
surrendering  to the  Corporation or any transfer agent of the  Corporation  the
certificate  or  certificates  for the shares to be  converted,  accompanied  by
written notice specifying the number of shares to be converted. Conversion shall
be deemed to have been effected upon receipt of the  certificate or certificates
for the shares to be  converted  accompanied  by written  notice of  election to
convert  specifying  the  number  of shares  to be  converted.  The date of such
receipt  is  referred  to  herein  as  the"Conversion   Date."  As  promptly  as
practicable  thereafter  (and after surrender of the certificate or certificates
representing  shares of Preferred Stock to the Corporation or any transfer agent
of the  Corporation)  the  Corporation  shall  issue and  deliver to or upon the
written order of such holder a  certificate  or  certificates  for the number of
full shares of Common Stock to which such holder is entitled and a check or cash
with respect to any  fractional  interest in a share of Common Stock as provided
in  subparagraph  3(f). The person in whose name the certificate or certificates
for  Common  Stock are to be issued  shall be deemed to have  become a holder of
record of such Common Stock on the applicable  Conversion  Date. Upon conversion
of only a portion of the number of shares covered by a certificate  representing
shares of Preferred  Stock  surrendered for  conversion,  the Corporation  shall
issue and deliver to or upon the written order of the holder of the  certificate
so  surrendered  for  conversion,  at  the  expense  of the  Corporation,  a new
certificate  covering the number of shares of Preferred Stock  representing  the
unconverted portion of the certificate so surrendered.

     (f) Fractional  Shares.  No fractional Shares or scrip shall be issued upon
conversion  of shares of  Preferred  Stock.  If more than one share of Preferred
Stock shall be  surrendered  for  conversion at any one time by the same holder,
the number of shares of Common Stock issuable upon  conversion  thereof shall be
computed on the basis of the  aggregate  number of shares of Preferred  Stock so
surrendered.  Instead of any fractional shares which would otherwise be issuable
upon conversion of any shares of Preferred  Stock,  the Corporation  shall pay a
cash  adjustment  in respect of such  fractional  interest in an amount equal to
that fractional interest of the then current market price.

          (g)  Conversion  Ratio  Adjustments.  The  Conversion  Ratio  shall be
subject to adjustment from time to time as follows:

     (i) Stock Dividends,  Subdivisions,  Reclassifications or Combinations.  If
the  Corporation  shall (x)  declare a dividend  or make a  distribution  on its
Common Stock in shares of its Common  Stock,  (y)  subdivide or  reclassify  the
outstanding  shares of Common  Stock  into a greater  number of  shares,  or (z)
combine or  reclassify  the  outstanding  Common Stock into a smaller  number of
shares,  the Conversion  Ratio in effect at the time of the record date for such
dividend or distribution or the effective date of such subdivision,  combination
or reclassification shall be proportionately  adjusted so that the holder of any
shares of Preferred Stock  surrendered  for conversion  after such date shall be
entitled  to receive  the number of shares of Common  Stock  which he would have
owned or been  entitled  to receive  had such  Preferred  Stock  been  converted
immediately prior to such date.  Successive  adjustments in the Conversion Ratio
shall be made whenever any event specified above shall occur.

               (ii) Other  Distributions.  In case the  Corporation  shall fix a
record  date for the making of a  distribution  to all  holders of shares of its
Common  Stock (w) of shares of any class  other than its Common  Stock or (x) of
evidence of  indebtedness  of the Corporation or any Subsidiary or (y) of assets
(excluding  cash  dividends or  distributions,  and  dividends or  distributions
referred to in  subparagraph  3(g)(i) above),  or (z) of rights or warrants,  in
each such case the Conversion Ratio in effect immediately prior thereto shall be
immediately  thereafter  proportionately  adjusted for such distribution so that
the holder of Preferred Stock would be entitled to receive the fair market value
(as  determined by the Board of  Directors,  whose  determination  in good faith
shall be  conclusive)  of what he would have been  entitled  to receive had such
Preferred Stock been converted prior to such distribution. Such adjustment shall
be made  successively  whenever  such a record date is fixed.  In the event that
such  distribution is not so made, the Conversion  Ratio then in effect shall be
readjusted,  effective as of the date when the Board of Directors determines not
to  distribute  such  shares,  evidences  of  indebtedness,  assets,  rights  or
warrants,  as the case may be, to the  Conversion  Ratio  which would then be in
effect if such record date had not been fixed.

               (iii) Consolidation,  Merger, Sale, Lease or Conveyance.  In case
of any  consolidation  with or merger of the  Corporation  with or into  another
corporation  or entity,  or in case of any sale,  lease or conveyance to another
corporation  or  entity of the  assets  of the  Corporation  as an  entirety  or
substantially as an entirety, each share of Preferred Stock shall after the date
of such consolidation, merger, sale, lease or conveyance be convertible into the
number of shares of stock or other  securities or property  (including  cash) to
which the shares of Common Stock  issuable  (at the time of such  consolidation,
merger,  sale,  lease or conveyance)  upon conversion of such share of Preferred
Stock would have been entitled upon such consolidation,  merger,  sale, lease or
conveyance;  and in any such case, if necessary, the provisions set forth herein
with respect to the rights and interests thereafter of the holders of the shares
of Preferred Stock shall be  appropriately  adjusted so as to be applicable,  as
nearly as may  reasonably  be, to any  shares  of stock or other  securities  or
property  thereafter  deliverable  on the  conversion of the shares of Preferred
Stock.

     (h) Statement Regarding Adjustments. Whenever the Conversion Ratio shall be
adjusted as provided in subparagraph 3(g), the Corporation shall forthwith file,
at the office of any transfer agent for the Preferred Stock and at the principal
office of the  Corporation,  a statement  showing in detail the facts  requiring
such  adjustment  and the  Conversion  Ratio that shall be in effect  after such
adjustment,  and the Corporation shall also cause a copy of such statement to be
sent by mail, first class postage prepaid, to each holder of shares of Preferred
Stock at its address appearing on the Corporation's  records. Where appropriate,
such  copy may be  given  in  advance  and may be  included  as part of a notice
required to be mailed under the provisions of subparagraph 3(i).

          (i) Notice to Holders.  In the event the Corporation  shall propose to
take  any  action  of the  type  described  in  clause  (i),  (ii) or  (iii)  of
subparagraph 3(g), the Corporation shall give notice to each holder of shares of
Preferred  Stock,  in the manner set forth in  subparagraph  3(h),  which notice
shall  specify the record date,  if any, with respect to any such action and the
approximate  date on which such action is to take place.  Such notice shall also
set forth such facts with respect  thereto as shall be  reasonably  necessary to
indicate  the effect of such  action (to the extent  such effect may be known at
the date of such notice) on the Conversion  Ratio and the number,  kind or class
of shares  which shall be  deliverable  upon  conversion  of shares of Preferred
Stock.  In the case of any action  which  would  require  the fixing of a record
date,  such  notice  shall be given at least 10 days prior to the date so fixed,
and in case of all other  action,  such  notice  shall be given at least 15 days
prior to the taking of such proposed action. Failure to give such notice, or any
defect therein, shall not affect the legality or validity of any such action.

     (j) Treasury Stock. For the purposes of this paragraph 3, the sale or other
disposition of any Common Stock theretofore held in the  Corporation's  treasury
shall be deemed to be an issuance thereof.

     (k) Costs. The Corporation  shall pay all documentary,  stamp,  transfer or
other  transactional taxes attributable to the issuance or delivery of shares of
Common Stock upon conversion of any shares of Preferred Stock; provided that the
Corporation  shall not be  required  to pay any taxes  which may be  payable  in
respect of any transfer  involved in the issuance or delivery of any certificate
for such  shares  in a name  other  than  that of the  holder  of the  shares of
Preferred Stock in respect of which such shares are being issued.

     (l) Reservation of Shares.  The  Corporation  shall reserve at all times so
long as any shares of Preferred Stock remain  outstanding,  free from preemptive
rights, out of its treasury stock (if applicable) or its authorized but unissued
shares of Common  Stock,  or both,  solely  for the  purpose  of  effecting  the
conversion of the shares of Preferred Stock,  sufficient  shares of Common Stock
to provide for the conversion of all outstanding shares of Preferred Stock.

     (m) Approvals. If any shares of Common Stock to be reserved for the purpose
of conversion of shares of Preferred Stock require registration with or approval
of any governmental  authority under any Federal or state law before such shares
may be validly issued or delivered,  then the Corporation will in good faith and
as expeditiously as possible  endeavor to secure such  registration or approval,
as the case may be. If,  and so long as,  any shares of Common  Stock into which
the shares of Preferred  Stock are then  convertible  are listed on any national
securities  exchange,  the  Corporation  will, if permitted by the rules of such
exchange,  list and keep  listed  on such  exchange,  upon  official  notice  of
issuance, all such shares issuable upon conversion.

     (n) Valid  Issuance.  All shares of Common  Stock  which may be issued upon
conversion  of  the  shares  of  Preferred  Stock  will  upon  issuance  by  the
Corporation be duly and validly issued,  fully paid and  nonassessable  and free
from all taxes, liens and charges with respect to the issuance thereof,  and the
Corporation shall take no action which will cause a contrary result.

     4. Voting Rights.  The holders of the shares of the Preferred Stock will be
entitled to one vote per share of Preferred  Stock held by them to vote upon all
matters which the holders of shares of the Company's Common Stock shall have the
right to vote. In all cases,  as a matter of law, where the holders of shares of
Preferred Stock shall have the right to vote separately as a class, such holders
will also be entitled to one vote per share of Preferred Stock held by them.

     The  affirmative  vote or consent of the holders of at least  two-thirds of
the  outstanding  shares of the  Preferred  Stock,  voting  as a class,  will be
required to (i) authorize, create or issue, or increase the authorized or issued
amount  of,  shares  of any  class or  series  of stock  ranking  senior  to the
Preferred  Stock,  either as to  dividends or upon  liquidation,  or (ii) amend,
alter or repeal (whether by merger,  consolidation  or otherwise) any provisions
of the  Company's  Articles of  Incorporation  or of the Statement of Resolution
establishing  this series of Preferred  Stock so as to materially  and adversely
affect  the  preferences,  special  rights  or powers  of the  Preferred  Stock;
provided,  however,  that any increase in the authorized  preferred stock or the
creation and issuance of any other series of preferred stock ranking on a parity
with or junior to the  Preferred  Stock  shall not be deemed to  materially  and
adversely affect such preferences, special rights or powers.

     5. Liquidation Rights.  Upon the dissolution,  liquidation or winding up of
the Corporation,  whether voluntary or involuntary, the holders of the shares of
this series of Preferred Stock shall be entitled to receive,  before any payment
or distribution of the assets of the  Corporation or proceeds  thereof  (whether
capital or surplus)  shall be made to or set apart for the holders of the Common
Stock or any other class or series of stock ranking junior to the shares of this
series of Preferred Stock upon  liquidation,  including  without  limitation the
Series C Preferred Stock, the amount of One Dollar and Fifteen Cents ($1.15) per
share,  plus a sum equal to all dividends on such shares  (whether or not earned
or declared) accrued and unpaid thereon to the date of final  distribution,  but
such  holders  shall  not be  entitled  to any  further  payment.  If,  upon any
liquidation,  dissolution  or winding-up of the  Corporation,  the assets of the
Corporation,  or proceeds thereof,  distributable among the holders of shares of
the Preferred  Stock and any other class or series of preferred stock ranking on
a parity with the Preferred Stock as to payments upon  liquidation,  dissolution
or  winding-up  shall be  insufficient  to pay in full the  preferential  amount
foresaid,  then such assets or the proceeds  thereof shall be distributed  among
such holders  ratably in accordance  with the respective  amounts which would be
payable on such shares if all amounts payable thereon were paid in full. For the
purposes of this paragraph 5, the voluntary sale, conveyance, lease, exchange or
transfer (for cash, shares of stock,  securities or other  consideration) of all
or  substantially  all the  property  or  assets  of the  Corporation  to,  or a
consolidation  or  merger  of the  Corporation  with,  one or more  corporations
(whether or not the Corporation is the corporation  surviving such consolidation
or merger) shall not be deemed to be a  liquidation,  dissolution or winding-up,
voluntary or involuntary.

     6.     Registration Rights.

     (a)  Registration  on Request.  Upon the  written  request of any holder or
holders of at least fifty-one percent (51%) in the aggregate number of shares of
the  Preferred  Stock  and/or  shares of Common  Stock  ("Shares")  issued  upon
conversion of such Preferred  Stock  (provided that in computing such 51% amount
the number of shares of  Preferred  Stock and  Common  Stock  shall be  weighted
proportionately  taking into account the Conversion  Ratio with respect to which
such shares of Common Stock were issued upon  conversion),  which  request shall
state the  intended  method of  disposition  by such holder or holders and shall
request that the Company effect the  registration of all or part of such Shares,
or the Shares  issuable upon the  conversion of such Preferred  Stock,  or both,
under the  Securities  Act of 1933,  as amended  (the"Act"),  the  Company  will
promptly give written  notice of such requested  registration  to all holders of
outstanding  Preferred Stock and Shares, and thereupon will use its best efforts
to effect the registration under the Act of:

     (i) the Shares which the Company has been so  requested  to  register,  for
disposition in accordance with the intended method of disposition stated in such
request, and

     (ii) all other  outstanding  Shares, or Shares issuable upon the conversion
of  Preferred  Stock,  the  holders  of which  shall have made  written  request
(stating the intended  method of disposition of such securities by such holders)
to the  Company  for  registration  thereof  within  thirty  (30) days after the
receipt of such written notice from the Company,

     all to the extent  requisite to permit the  disposition (in accordance with
the  intended  methods  thereof as  aforesaid)  by the  holders of the Shares so
registered  and  to  maintain  such  registration  in  effect  for a  period  of
twenty-four (24) months from the effective date of such registration  statement;
provided,  that the  Company  shall not be  required to register or use its best
efforts to effect any  registration  of Shares  under the Act  pursuant  to this
paragraph  6(a)  more  than  once.  In the  event  that,  as a  result  of  such
registration,  another person with incidental registration rights granted by the
company  requests  that the Company  include  securities  of such person in such
registration,  such  request  will not  result in a  reduction  in the number of
securities of the holder or holders of the  Preferred  Stock and/or Shares to be
included in such registration.

     The Company shall have no obligation to register or use its best efforts to
effect any  registration  of Shares under the Act  pursuant to this  paragraph 6
which  would be in  conflict  with the  obligations  of any holder or holders of
Preferred Stock and/or Shares under any  confidentiality  agreement between such
holder or holders and the Company  entered into in connection  with the offering
of the Preferred Stock to such holder or holders.

          (b)  Incidental  Registration.  If the Company at any time proposes to
register  any of its  securities  under  the Act  (otherwise  than  pursuant  to
paragraph 6(a) and other than a  registration  on Form S-8, or the form, if any,
which  supplants  such Form),  it will at such time give  written  notice to all
holders of outstanding Preferred Stock and Shares of its intention to do so and,
upon the written  request of any such holder made within  thirty (30) days after
the receipt of any such notice (which request shall specify the Shares  intended
to be disposed of by such holder and state the  intended  method of  disposition
thereof),  the Company will use its best  efforts to cause all such  outstanding
Shares,  or Shares issuable upon the conversion of Preferred  Stock, the holders
of which shall have so requested  the  registration  thereof,  to be  registered
under the Act to the extent  requisite to permit the  disposition (in accordance
with the intended  methods  thereof as aforesaid)  of the Shares so  registered;
provided  that,  if in the good faith  judgment of the managing  underwriter  or
underwriters  of a then proposed  public  offering of the Company's  securities,
such  registration  of such Shares would  materially  and adversely  affect such
public offering, then in such event the number of Shares and other securities to
be registered by the Company shall each be proportionally reduced to such number
as shall be  acceptable  to the  managing  underwriter,  subject to Section 6(a)
above.

     (c) Registration Procedures. If and whenever the Company is required to use
its best efforts to effect or cause the registration of any Shares under the Act
as provided in this paragraph 6, the Company will, as expeditiously as possible:

     (i)  prepare  and  file  with  the  Securities   and  Exchange   Commission
(the"Commission")  a registration  statement with respect to such Shares and use
its best efforts to cause such registration statement to become effective;

     (ii) prepare and file with the Commission  such  amendments and supplements
to such registration  statement and the prospectus used in connection  therewith
as may be  necessary  to keep such  registration  statement  effective  for such
period not exceeding  twenty-four  (24) months from the  effective  date of such
registration  statement as may be necessary to comply with the provisions of the
Act with respect to the  disposition of all Shares covered by such  registration
statement  during  such  period  in  accordance  with the  intended  methods  of
disposition  by the seller or  sellers  thereof  set forth in such  registration
statement;

     (iii)  furnish to each  seller of such Shares such number of copies of such
registration  statement and of each such  amendment and  supplement  thereto (in
each case  including  all  exhibits),  such  number of copies of the  prospectus
included in such registration  statement (including each preliminary  prospectus
and, if any seller shall so request, a summary  prospectus),  in conformity with
the  requirements  of the Act,  and such  other  documents,  as such  seller may
reasonably request in order to facilitate the disposition of the Shares owned by
such seller;

     (iv) use its best  efforts to  register or qualify  such Shares  covered by
such registration statement under such other securities or blue sky laws of such
jurisdictions  as each seller shall  reasonably  request and as agreed to by the
Corporation,  and do any and all other acts and things  which may be  reasonably
necessary or advisable to enable such seller to consummate  the  disposition  in
such jurisdictions of the Shares owned by such seller; and

               (v)  notify  each  seller  of any  such  Shares  covered  by such
registration  statement,  at any time  when a  prospectus  relating  thereto  is
required  to  be  delivered  under  the  Act  within  the  period  mentioned  in
subdivision  (b) of this  paragraph  6(c),  of the  happening  of any event as a
result of which the prospectus included in such registration  statement, as then
in effect, includes an untrue statement of a material fact or omits to state any
material fact required to be stated  therein or necessary to make the statements
therein not misleading in the light of the circumstances  then existing,  and at
the request of any such seller  prepare and furnish to such seller a  reasonable
number of copies of a supplement to or an amendment of such prospectus as may be
necessary so that,  as  thereafter  delivered to the  purchasers of such Shares,
such prospectus shall not include an untrue statement of a material fact or omit
to state a material fact required to be stated  therein or necessary to make the
statements  therein  not  misleading  in the  light  of the  circumstances  then
existing.

     (d)  Registration   Expenses.   All  expenses  incident  to  the  Company's
performance  of  or  compliance  with  this  paragraph  6,  including,   without
limitation,  all  registration  and filing fees,  fees and expenses of complying
with securities or blue sky laws,  printing  expenses and fees and disbursements
of counsel for the Company and of independent pubic  accountants,  but excluding
underwriting  commissions and discounts,  the fees of any counsel engaged by the
holder or holders,  and any filing  fees  associated  with  shares of  Preferred
Stock, but not Common Stock, being listed with a national securities exchange or
quoted on the NASDAQ National Market System or Small Cap Market,  shall be borne
by the Company.

          (e)     Indemnification.

               (i) In the event of any  registration of any Shares under the Act
pursuant to this paragraph 6, the Company will, to the extent  permitted by law,
indemnify  and hold harmless the seller of such Shares and each  underwriter  of
such  securities  and each other  person,  if any, who  controls  such seller or
underwriter within the meaning of the Act, against any losses, claims,  damages,
or  liabilities,  joint or  several,  to which  such  seller or  underwriter  or
controlling  person may become subject,  under the Act or otherwise,  insofar as
such losses,  claims,  damages,  or liabilities (or actions in respect  thereof)
arise  out of or are based  upon (x) any  untrue  statement  or  alleged  untrue
statement of any material fact contained,  on the effective date thereof, in any
registration  statement under which such  securities  were registered  under the
Act, any preliminary  prospectus or final prospectus  contained therein,  or any
amendment or  supplement  thereto,  or (y) any  omission or alleged  omission to
state therein a material fact required to be stated therein or necessary to make
the  statements  therein not  misleading;  and the Company will  reimburse  such
seller and each such underwriter and each such controlling  person for any legal
or  any  other  expenses   reasonably   incurred  by  them  in  connection  with
investigating or defending any such loss, claim, damage,  liability,  or action,
provided  that the  Company  shall not be liable in any such case to the  extent
that any such loss,  claim,  damage, or liability arises out of or is based upon
an untrue  statement or alleged untrue statement or omission or alleged omission
made in such  registration  statement,  any such preliminary  prospectus,  final
prospectus,  amendment or supplement  in reliance  upon and in  conformity  with
written information furnished to the Company through an instrument duly executed
by such seller or underwriter specifically for use in the preparation thereof.

     (ii) The Company may require, as a condition to including any Shares in any
registration  statement filed pursuant to paragraph 6(c), that the Company shall
have received an undertaking  satisfactory to it from the prospective  seller of
such Shares and from each  underwriter  of such Shares,  to  indemnify  and hold
harmless  (in the same manner and to the same  extent as set forth in  paragraph
6(e)(i)) the Company,  each director of the Company, each officer of the Company
who shall sign such  registration  statement  and any person  who  controls  the
Company within the meaning of the Act, with respect to any statement or omission
from such registration statement, any preliminary prospectus or final prospectus
contained therein,  or any amendment or supplement thereto, if such statement or
omission was made in reliance  upon and in conformity  with written  information
furnished to the Company  through an instrument  duly executed by such seller or
underwriter  specifically  for  use  in the  preparation  of  such  registration
statement, preliminary prospectus, final prospectus, amendment, or supplement.

               (iii) Promptly after receipt by an indemnified party of notice of
the  commencement  of any action  involving a claim referred to in the preceding
subparagraphs of this paragraph 6(e), such indemnified party will, if a claim in
respect thereof is to be made against an indemnifying party, give written notice
to the latter of the  commencement of such action,  provided that the failure of
any indemnified  party to give notice as provided  therein shall not relieve the
indemnifying  party of its obligations under the preceding  subdivisions of this
paragraph 6(e). In case any such action is brought against an indemnified party,
the  indemnifying  party will be  entitled to  participate  in and to assume the
defense thereof, jointly with any other indemnifying party similarly notified to
the  extent  that it may wish,  with  counsel  reasonably  satisfactory  to such
indemnified  party,  and  after  notice  from  the  indemnifying  party  to such
indemnified  party  of  its  election  so to  assume  the  defense  thereof  the
indemnifying party will not be liable to such indemnified party for any legal or
other  expenses  subsequently  incurred  by the  latter in  connection  with the
defense  thereof.  No  indemnifying  party,  in the defense of any such claim or
litigation, shall, except with the consent of each indemnified party, consent to
entry of any judgment or enter into any settlement  which does not include as an
unconditional  term  thereof  the giving by the  claimant or  plaintiff  to such
indemnified  party of a release  from all  liability in respect to such claim or
litigation.

     7.     Redemption Rights.

          (a) Company's  Redemption Option.  Except for any redemption which the
Company would be prohibited  from effecting  under  applicable law, and provided
the shares of  Preferred  Stock of a holder have not earlier  been  converted in
accordance  with the  provisions  hereof,  the shares of Preferred  Stock may be
redeemed by the Company,  in whole or in part, at the option of the Company upon
written  notice by the  Company to the  holders of  Preferred  Stock at any time
after  December 1, 2001,  in the event that the  Preferred  Stock of one or more
holders has not been  converted  pursuant to the terms  hereof on or before such
date.  The Company  shall redeem each share of  Preferred  Stock of such holders
within  thirty (30) days of the  Company's  delivery of the above notice to such
holders and such holders shall surrender the  certificate(s)  representing  such
shares of Preferred Stock. For any partial  redemptions the Company shall redeem
shares in proportion to the number of shares held by each holder. The redemption
amount shall be One Dollar and  Seventy-five  Cents  ($1.75) per share,  plus in
each case  accrued and unpaid  dividends  thereon to the date of payment of such
amount (the total sum so payable on any such redemption being herein referred to
as the"redemption price").

     (b) Redemption Notice.  Notice of any redemption pursuant to this paragraph
7 shall be mailed to the party or parties required to receive such notice at the
principal  office or  residence  address  for such party or  parties.  Each such
notice shall  state:  (1) the  election of the  redemption  option and the facts
which give rise to such option;  and (2) the number of shares of Preferred Stock
which are being elected to be redeemed. From and after the date of the Company's
payment of the  redemption  price to such holder or holders in  accordance  with
such  redemption  notice  (the"redemption   date"),   notwithstanding  that  any
certificates for such shares shall not have been  surrendered for  cancellation,
the shares represented thereby shall no longer be deemed outstanding, the rights
to receive dividends and distributions  shall cease to accrue from and after the
redemption  date,  and all  rights of such  holder or  holders  of the shares of
Preferred Stock as a stockholder of the Corporation with respect to such shares,
shall cease and terminate.

     8. Special rights. So long as, but only so long as, the shares of Preferred
Stock are held by WEDGE Energy Services,  L.L.C.,  a Delaware limited  liability
company  ("WEDGE"),  or by an affiliate of WEDGE  (collectively  "Holder"),  the
shares of Preferred Stock shall have the following special rights:

          (a)     Right of Participation.

     (i) Grant of Right of Participation. The Company hereby grants the Holder a
right of participation  to participate in any additional  equity offerings which
the Company may offer, up to the Holder  Percentage (as defined  below),  on the
following  terms and  conditions.  In the event that the Company has  received a
bona fide offer  (which the  Company  desires  to  accept)  with  respect to the
issuance of any equity securities (including,  without limitation, any common or
preferred stock, any options  (excluding the Company's 1993 Stock Option Plan or
any future  employee stock option plan approved by the Company's  shareholders),
warrants,  rights, unsecured convertible notes, convertible debentures, or other
convertible  securities),  the Company  shall  immediately  give written  notice
thereof (the  "Notice") to the Holder of the Preferred  Stock.  The Notice shall
state  the name of the party  proposing  to  provide  the  offering  and all the
pertinent  terms and conditions of such  offering.  This right shall expire upon
the later to occur of the  following:  (a) the  conversion  by the Holder of the
Preferred Stock into Common Stock,  or (b) the tenth  anniversary of the date of
the filing of this Statement.

               (ii) Procedure. The Holder shall have fourteen (14) days from the
date the Notice was given to  indicate  to the  Company,  in  writing,  that the
Holder  undertakes to participate in the offering under the terms and conditions
set  forth in the  Notice.  If the  Holder  undertakes  to  participate  in such
offering, then the Company shall be obligated to accept such participation up to
the Holder  Percentage upon the terms and conditions set forth in the Notice and
the parties  shall use their best efforts to enter into a  definitive  agreement
relating to such offering.  In the event that the Holder declines to participate
in such offering,  the Company shall have the right to accept such offering from
the third party  without  participation  by the Holder  provided that it does so
upon the terms and  conditions  set forth in the Notice.  In the event that such
offering is not consummated within sixty (60) days after the date the Notice was
given,  the Company shall not consummate  such offering  without again complying
with this subparagraph 8(a)(ii).

               (iii) Holder  Percentage.  For purposes hereof,  the term "Holder
Percentage" shall mean that percentage calculated,  on a fully diluted basis, as
if the Holder had (a)  converted the  Preferred  Stock into Common Stock,  which
number shall constitute the numerator, and (b) divided by the denominator, which
shall be equal to the  total  number  of  shares  of  Common  Stock  issued  and
outstanding  as of such  date,  plus (i) that  number of shares of Common  Stock
issuable  upon the  conversion  of all  convertible  securities  of the Company,
including,  without  limitation,  the Preferred  Stock,  and (ii) that number of
shares of Common  Stock  issuable  upon the exercise of all options and warrants
utilizing the "treasury method" as of such date. Under the treasury method, only
shares  issuable  upon the  exercise of "in the money"  options and warrants are
considered  in the  calculation  and the net  dilution  is that number of shares
issuable  upon such  exercise net of that number of shares which could have been
purchased with the proceeds from the exercise of the options and warrants at the
then market price.  For example,  assuming  100,000 options are outstanding at a
strike price of $1.00 per share and that the market price of the Common Stock is
$2.50 per share,  under the treasury  method,  the proceeds from the exercise of
the options would equal $100,000 and such proceeds would purchase  40,000 shares
of Common  Stock at the market  price of $2.50 per share.  The net  dilution  is
60,000  shares,  which  number of shares is utilized in the  calculation  of the
Holder Percentage under the above formula.

          (b) Restriction on Payment of Cash Dividends and Interest. The Company
agrees that so long as the Holder owns shares of Preferred Stock representing at
least ten percent (10%) of the shares of capital stock of the Company on a fully
diluted  basis  utilizing  the  "treasury  method" as described in  subparagraph
8(a)(iii) above, it shall not pay any cash dividends or any interest accruals on
any equity security or any debt security (excluding any Superior Indebtedness as
defined in that certain Debenture Agreement dated December 10, 1999, between the
Company and WEDGE (the "Debenture Agreement") on file at the Company's principal
office),  in  existence  as of the date hereof or created  hereafter  unless and
until the Company's earnings before deduction of interest,  taxes,  depreciation
and  amortization  ("EBITDA")  for the six (6) months ended with the quarter for
the last  quarterly  report  which the  Company is  required to furnish to WEDGE
under  Section  4.01  of the  Debenture  Agreement  are  more  than  125% of the
Company's  obligations  for all  dividends  and  interest due and payable on all
outstanding securities of the Company as of such time.

     (c) Prohibition  Against Capital  Expenditures.  The Company agrees that so
long as Holder owns shares of Preferred Stock  representing at least ten percent
(10%) of the shares of capital  stock of the  Company on a fully  diluted  basis
utilizing the "treasury  method" as described in subparagraph  8(a)(iii)  above,
the Company will not incur, or commit to incur, any capital  expenditures of any
kind or nature  in  excess  of  $50,000  without  the  approval  by the Board of
Directors of the Company,  and, in addition,  the Company agrees that, until the
Company  has  expended  the  $2,500,000  in  proceeds  from the  issuance of the
Debenture,  from the date hereof there shall be no capital expenditure in excess
of $50,000 without the affirmative written consent of WEDGE or its affiliate.

     9.  Exclusion of Other Rights.  Except as may otherwise be required by law,
the  shares of  Preferred  Stock  shall not have any  preferences  or  relative,
participating,  optional or other special rights,  other than those specifically
set forth in this  resolution  (as such  resolution  may be amended from time to
time) and in the  Corporation's  Certificate  of  Incorporation.  The  shares of
Preferred Stock shall have no preemptive or subscription rights.

     10. Severability of Provisions.  If any right,  preference or limitation of
the Preferred  Stock set forth in this  resolution  (as such  resolution  may be
amended from time to time) is invalid,  unlawful or incapable of being  enforced
by reason of any rule or law or public policy, all other rights, preferences and
limitations  set forth in this  resolution  (as so  amended)  which can be given
effect  without the invalid,  unlawful or  unenforceable  right,  preference  or
limitation  herein set forth shall be deemed  enforceable and not dependent upon
any other such right, preference or limitation unless so expressed herein.

     11. Status of Reacquired Shares.  Shares of Preferred Stock which have been
issued and reacquired in any manner shall (upon  compliance  with any applicable
provisions of the laws of the State of Texas) have the status of authorized  and
unissued shares of Preferred Stock issuable in series  undesignated as to series
and may be redesignated and reissued.

                                  [END]


<PAGE>



















                                     EXHIBIT "C"

                          Terms of Series D Preferred Stock


<PAGE>




                                                                      12/10/99

                       STATEMENT OF RESOLUTION ESTABLISHING
                     SERIES D 8% CONVERTIBLE PREFERRED STOCK OF

                                TGC INDUSTRIES, INC.

     Pursuant  to  the   provisions  of  Article  2.13  of  the  Texas  Business
Corporation Act, TGC, Industries, Inc., a Texas corporation (the"Corporation" or
the"Company"),  has adopted the following  resolution by all necessary action on
the part of the  Corporation  at a special  meeting of the Board of Directors on
November  30,  1999,  authorizing  the  creation  and  issuance  of a series  of
preferred stock designated as Series D 8% Convertible Preferred Stock:

     RESOLVED,  that pursuant to the authority  vested in the Board of Directors
of the Corporation by Article 4.b of the  Corporation's  Certificate of Restated
Articles  of  Incorporation,  as  amended,  a series of  preferred  stock of the
Corporation  be, and it is hereby,  created out of the  authorized  but unissued
shares of the capital  stock of the  Corporation,  such series to be  designated
Series D 8% Convertible  Preferred Stock  (the"Preferred  Stock"), to consist of
2,750,000  shares,  of which the preferences and relative and other rights,  and
the qualifications,  limitations or restrictions thereof,  shall be (in addition
to those  set  forth  in the  Corporation's  Certificate  of  Incorporation,  as
amended) as follows:

     1. Certain  Definitions.  Unless the context otherwise requires,  the terms
defined in this paragraph 1 shall have, for all purposes of this resolution, the
meanings herein specified.

     Common Stock. The term"Common Stock" shall mean all shares now or hereafter
authorized of any class of Common Stock of the  Corporation  and any other stock
of the Corporation, howsoever designated, authorized after the Issue Date, which
has the  right  (subject  always  to prior  rights  of any  class or  series  of
preferred  stock) to participate in the  distribution of the assets and earnings
of the Corporation without limit as to per share amount.

     Conversion Date. The term"Conversion Date" shall have the meaning set forth
in subparagraph 3(e) below.

     Conversion Ratio. The  term"Conversion  Ratio" shall mean the ratio used to
determine the number of shares of Common Stock  deliverable  upon  conversion of
the Preferred Stock,  subject to adjustment in accordance with the provisions of
paragraph 3 below.

     Issue  Date.  The  term"Issue  Date"  shall  mean the date  that  shares of
Preferred Stock are first issued by the Corporation.

     Series C Preferred  Stock.  The term "Series C Preferred  Stock" shall mean
the Corporation's Series C 8% Convertible Exchangeable Preferred Stock.

     Subsidiary. The term"Subsidiary" shall mean any corporation of which shares
of stock  possessing at least a majority of the general voting power in electing
the board of directors are, at the times as of which any  determination is being
made,  owned by the Corporation,  whether directly or indirectly  through one or
more Subsidiaries.

     2. Dividends.  The Preferred Stock shall have the following dividend rights
which  rights are pari passu  with the rights of any  outstanding  shares of the
Company's Series C 8% Convertible Exchangeable Preferred Stock.

     (a)  Declaration  of  Dividends.  The holders of shares of Preferred  Stock
shall be entitled to receive cumulative cash dividends,  when and as declared by
the Board of Directors out of funds  legally  available  therefor,  at a rate of
eight (8%) per annum and no more  ($0.092  per share per annum  based on the per
share liquidation  value of $1.15),  before any dividend or distribution in cash
or other property  (other than dividends  payable in stock ranking junior to the
Preferred Stock as to dividends and upon liquidation, dissolution or winding-up)
on any  class or  series  of  stock of the  Corporation  ranking  junior  to the
Preferred  Stock as to dividends or on  liquidation,  dissolution  or winding-up
shall be declared or paid or set apart for payment.

     (b)  Payment  of  Dividends.  Dividends  on the  Preferred  Stock  shall be
payable, when and as declared by the Board of Directors on December 1 and June 1
of each  year,  commencing  June 1,  2000  (each  such  date  being  hereinafter
individually  a"Dividend  Payment Date" and  collectively  the"Dividend  Payment
Dates"),  except that if such date is a Saturday,  Sunday or legal  holiday then
such dividend shall be payable on the first immediately  preceding  calendar day
which is not a Saturday,  Sunday or legal holiday,  to holders of record as they
appear on the books of the Corporation on such respective  dates,  not exceeding
sixty days  preceding  such  Dividend  Payment Date, as may be determined by the
Board of  Directors  in advance  of the  payment  of each  particular  dividend.
Dividends in arrears may be declared and paid at any time,  without reference to
any regular  Dividend  Payment Date, to holders of record on such date as may be
fixed by the Board of Directors of the Corporation.  Dividends declared and paid
in arrears shall be applied first to the earliest dividend period or periods for
which any  dividends  remain  outstanding.  The amount of dividends  payable per
share of this Series for each dividend  period shall be computed by dividing the
annual rate of eight percent (8%) by two (2).  Dividends  payable on this Series
for the initial  period and for any period less than a full  semi-annual  period
shall be  computed  on the basis of a  360-day  year of  twelve  30-day  months.
Dividends shall be payable in cash, provided that for each dividend declared and
payable  through  December 1, 2000, the dividend  payment shall be by payment in
kind  securities  by issuance of  additional  shares of  Preferred  Stock with a
liquidation  value equal to the amount of the cash dividend  payment which would
have been paid ("PIK Dividend"). For each dividend payment due and payable after
December 1, 2000, payment shall be by cash or by PIK Dividend at the election of
the holders by written notice to the Corporation,  provided that the Corporation
shall  only  pay a PIK  Dividend  and  not a  cash  dividend  in the  event  the
Corporation's  earnings before  deduction of interest,  taxes,  depreciation and
amortization  (EBITDA) for the six (6) months  ended with the  previous  quarter
(for the December 1 payment:  the six (6) months ended September 30; and for the
June 1 payment:  the six (6) months  ended  March 31) are less than one  hundred
twenty-five  percent  (125%) of the  Corporation's  obligation for such dividend
payment and for all other  dividends  and  interest due and payable on all other
outstanding securities of the Corporation as of such time.

     (c) Dividends  Cumulative.  Preferred  Stock shall be cumulative and accrue
from and after the date of original issuance thereof, whether or not declared by
the Board of Directors. Accrued dividends shall not bear interest.

     (d)  Dividend  Restriction.  No cash  dividend may be declared on any other
class or series of stock  ranking  on a parity  with the  Preferred  Stock as to
dividends in respect of any dividend  period  unless there shall also be or have
been declared on the Preferred  Stock like dividends for all periods  coinciding
with or ending  before such  semi-annual  period,  ratably in  proportion to the
respective   annual  dividend  rates  fixed  therefor  and  the  total  dividend
obligation with respect thereto.

     3. Conversion  Rights. The Preferred Stock shall be convertible into Shares
of Common Stock as follows:

     (a)  Conversion  Right.  The holder of any shares of Preferred  Stock shall
have the right,  at such  holder's  option,  at any time to convert  any of such
shares of  Preferred  Stock into fully paid and  nonassessable  shares of Common
Stock  at the  Conversion  Ratio  provided  for in  subparagraph  3(d)  below by
surrendering  shares  of  Preferred  Stock for  conversion  in  accordance  with
subparagraph 3(e) below.

     (b) Continuance of Conversion  Right.  The Conversion Right set forth above
will continue so long as such Preferred Stock is outstanding with respect to any
stock not redeemed in accordance with the terms of paragraph 7.

     (c) Surrender of Shares on Exercise of Conversion  Right. In the event that
any holder of shares of Preferred  Stock  surrenders such shares for conversion,
such  holder  will be issued the number of shares of Common  Stock to which such
holder is entitled pursuant to the provisions of subparagraph 3(d) in the manner
provided for in subparagraph  3(e). The shares of Preferred Stock deemed to have
been surrendered will have the status described in paragraph 11 below.

     (d) Conversion  Ratio. Each share of Preferred Stock may, at the discretion
of the  holder  thereof,  be  converted  into  shares  of  Common  Stock  of the
Corporation  at the  conversion  ratio of one (1) share of Common Stock for each
share  of  Preferred  Stock,  as  such  conversion  ratio  may be  adjusted  and
readjusted from time to time in accordance with  subparagraph  3(g) hereof (such
conversion  ratio,  as adjusted and readjusted and in effect at any time,  being
herein called  the"Conversion  Ratio").  The Conversion  Ratio referred to above
will be subject to adjustment as set forth in subparagraph 3(g).

     (e) Mechanics of  Conversion.  The holder of any shares of Preferred  Stock
may exercise the conversion right specified in subparagraph 3(a) by surrendering
to the  Corporation or any transfer agent of the  Corporation the certificate or
certificates  for the shares to be  converted,  accompanied  by  written  notice
specifying the number of shares to be converted.  Conversion  shall be deemed to
have been  effected  upon receipt of the  certificate  or  certificates  for the
shares to be  converted  accompanied  by written  notice of  election to convert
specifying  the number of shares to be  converted.  The date of such  receipt is
referred  to  herein  as  the"Conversion   Date."  As  promptly  as  practicable
thereafter (and after surrender of the certificate or certificates  representing
shares  of  Preferred  Stock to the  Corporation  or any  transfer  agent of the
Corporation)  the  Corporation  shall  issue and  deliver to or upon the written
order of such holder a certificate or certificates for the number of full shares
of  Common  Stock to which  such  holder  is  entitled  and a check or cash with
respect to any  fractional  interest  in a share of Common  Stock as provided in
subparagraph  3(f). The person in whose name the certificate or certificates for
Common  Stock are to be issued shall be deemed to have become a holder of record
of such Common Stock on the applicable  Conversion Date. Upon conversion of only
a portion of the number of shares covered by a certificate  representing  shares
of Preferred Stock  surrendered for conversion,  the Corporation shall issue and
deliver  to or upon  the  written  order of the  holder  of the  certificate  so
surrendered for conversion, at the expense of the Corporation, a new certificate
covering the number of shares of Preferred  Stock  representing  the unconverted
portion of the certificate so surrendered.

     (f) Fractional  Shares.  No fractional Shares or scrip shall be issued upon
conversion  of shares of  Preferred  Stock.  If more than one share of Preferred
Stock shall be  surrendered  for  conversion at any one time by the same holder,
the number of shares of Common Stock issuable upon  conversion  thereof shall be
computed on the basis of the  aggregate  number of shares of Preferred  Stock so
surrendered.  Instead of any fractional shares which would otherwise be issuable
upon conversion of any shares of Preferred  Stock,  the Corporation  shall pay a
cash  adjustment  in respect of such  fractional  interest in an amount equal to
that fractional interest of the then current market price.

          (g)  Conversion  Ratio  Adjustments.  The  Conversion  Ratio  shall be
subject to adjustment from time to time as follows:

     (i) Stock Dividends,  Subdivisions,  Reclassifications or Combinations.  If
the  Corporation  shall (x)  declare a dividend  or make a  distribution  on its
Common Stock in shares of its Common  Stock,  (y)  subdivide or  reclassify  the
outstanding  shares of Common  Stock  into a greater  number of  shares,  or (z)
combine or  reclassify  the  outstanding  Common Stock into a smaller  number of
shares,  the Conversion  Ratio in effect at the time of the record date for such
dividend or distribution or the effective date of such subdivision,  combination
or reclassification shall be proportionately  adjusted so that the holder of any
shares of Preferred Stock  surrendered  for conversion  after such date shall be
entitled  to receive  the number of shares of Common  Stock  which he would have
owned or been  entitled  to receive  had such  Preferred  Stock  been  converted
immediately prior to such date.  Successive  adjustments in the Conversion Ratio
shall be made whenever any event specified above shall occur.

               (ii) Other  Distributions.  In case the  Corporation  shall fix a
record  date for the making of a  distribution  to all  holders of shares of its
Common  Stock (w) of shares of any class  other than its Common  Stock or (x) of
evidence of  indebtedness  of the Corporation or any Subsidiary or (y) of assets
(excluding  cash  dividends or  distributions,  and  dividends or  distributions
referred to in  subparagraph  3(g)(i) above),  or (z) of rights or warrants,  in
each such case the Conversion Ratio in effect immediately prior thereto shall be
immediately  thereafter  proportionately  adjusted for such distribution so that
the holder of Preferred Stock would be entitled to receive the fair market value
(as  determined by the Board of  Directors,  whose  determination  in good faith
shall be  conclusive)  of what he would have been  entitled  to receive had such
Preferred Stock been converted prior to such distribution. Such adjustment shall
be made  successively  whenever  such a record date is fixed.  In the event that
such  distribution is not so made, the Conversion  Ratio then in effect shall be
readjusted,  effective as of the date when the Board of Directors determines not
to  distribute  such  shares,  evidences  of  indebtedness,  assets,  rights  or
warrants,  as the case may be, to the  Conversion  Ratio  which would then be in
effect if such record date had not been fixed.

               (iii) Consolidation,  Merger, Sale, Lease or Conveyance.  In case
of any  consolidation  with or merger of the  Corporation  with or into  another
corporation  or entity,  or in case of any sale,  lease or conveyance to another
corporation  or  entity of the  assets  of the  Corporation  as an  entirety  or
substantially as an entirety, each share of Preferred Stock shall after the date
of such consolidation, merger, sale, lease or conveyance be convertible into the
number of shares of stock or other  securities or property  (including  cash) to
which the shares of Common Stock  issuable  (at the time of such  consolidation,
merger,  sale,  lease or conveyance)  upon conversion of such share of Preferred
Stock would have been entitled upon such consolidation,  merger,  sale, lease or
conveyance;  and in any such case, if necessary, the provisions set forth herein
with respect to the rights and interests thereafter of the holders of the shares
of Preferred Stock shall be  appropriately  adjusted so as to be applicable,  as
nearly as may  reasonably  be, to any  shares  of stock or other  securities  or
property  thereafter  deliverable  on the  conversion of the shares of Preferred
Stock.

     (h) Statement Regarding Adjustments. Whenever the Conversion Ratio shall be
adjusted as provided in subparagraph 3(g), the Corporation shall forthwith file,
at the office of any transfer agent for the Preferred Stock and at the principal
office of the  Corporation,  a statement  showing in detail the facts  requiring
such  adjustment  and the  Conversion  Ratio that shall be in effect  after such
adjustment,  and the Corporation shall also cause a copy of such statement to be
sent by mail, first class postage prepaid, to each holder of shares of Preferred
Stock at its address appearing on the Corporation's  records. Where appropriate,
such  copy may be  given  in  advance  and may be  included  as part of a notice
required to be mailed under the provisions of subparagraph 3(i).

          (i) Notice to Holders.  In the event the Corporation  shall propose to
take  any  action  of the  type  described  in  clause  (i),  (ii) or  (iii)  of
subparagraph 3(g), the Corporation shall give notice to each holder of shares of
Preferred  Stock,  in the manner set forth in  subparagraph  3(h),  which notice
shall  specify the record date,  if any, with respect to any such action and the
approximate  date on which such action is to take place.  Such notice shall also
set forth such facts with respect  thereto as shall be  reasonably  necessary to
indicate  the effect of such  action (to the extent  such effect may be known at
the date of such notice) on the Conversion  Ratio and the number,  kind or class
of shares  which shall be  deliverable  upon  conversion  of shares of Preferred
Stock.  In the case of any action  which  would  require  the fixing of a record
date,  such  notice  shall be given at least 10 days prior to the date so fixed,
and in case of all other  action,  such  notice  shall be given at least 15 days
prior to the taking of such proposed action. Failure to give such notice, or any
defect therein, shall not affect the legality or validity of any such action.

     (j) Treasury Stock. For the purposes of this paragraph 3, the sale or other
disposition of any Common Stock theretofore held in the  Corporation's  treasury
shall be deemed to be an issuance thereof.

     (k) Costs. The Corporation  shall pay all documentary,  stamp,  transfer or
other  transactional taxes attributable to the issuance or delivery of shares of
Common Stock upon conversion of any shares of Preferred Stock; provided that the
Corporation  shall not be  required  to pay any taxes  which may be  payable  in
respect of any transfer  involved in the issuance or delivery of any certificate
for such  shares  in a name  other  than  that of the  holder  of the  shares of
Preferred Stock in respect of which such shares are being issued.

     (l) Reservation of Shares.  The  Corporation  shall reserve at all times so
long as any shares of Preferred Stock remain  outstanding,  free from preemptive
rights, out of its treasury stock (if applicable) or its authorized but unissued
shares of Common  Stock,  or both,  solely  for the  purpose  of  effecting  the
conversion of the shares of Preferred Stock,  sufficient  shares of Common Stock
to provide for the conversion of all outstanding shares of Preferred Stock.

     (m) Approvals. If any shares of Common Stock to be reserved for the purpose
of conversion of shares of Preferred Stock require registration with or approval
of any governmental  authority under any Federal or state law before such shares
may be validly issued or delivered,  then the Corporation will in good faith and
as expeditiously as possible  endeavor to secure such  registration or approval,
as the case may be. If,  and so long as,  any shares of Common  Stock into which
the shares of Preferred  Stock are then  convertible  are listed on any national
securities  exchange,  the  Corporation  will, if permitted by the rules of such
exchange,  list and keep  listed  on such  exchange,  upon  official  notice  of
issuance, all such shares issuable upon conversion.

     (n) Valid  Issuance.  All shares of Common  Stock  which may be issued upon
conversion  of  the  shares  of  Preferred  Stock  will  upon  issuance  by  the
Corporation be duly and validly issued,  fully paid and  nonassessable  and free
from all taxes, liens and charges with respect to the issuance thereof,  and the
Corporation shall take no action which will cause a contrary result.

     4. Voting Rights.  The holders of the shares of the Preferred Stock will be
entitled to one vote per share of Preferred  Stock held by them to vote upon all
matters which the holders of shares of the Company's Common Stock shall have the
right to vote. In all cases,  as a matter of law, where the holders of shares of
Preferred Stock shall have the right to vote separately as a class, such holders
will also be entitled to one vote per share of Preferred Stock held by them.

     The  affirmative  vote or consent of the holders of at least  two-thirds of
the  outstanding  shares of the  Preferred  Stock,  voting  as a class,  will be
required to (i) authorize, create or issue, or increase the authorized or issued
amount  of,  shares  of any  class or  series  of stock  ranking  senior  to the
Preferred  Stock,  either as to  dividends or upon  liquidation,  or (ii) amend,
alter or repeal (whether by merger,  consolidation  or otherwise) any provisions
of the  Company's  Articles of  Incorporation  or of the Statement of Resolution
establishing  this series of Preferred  Stock so as to materially  and adversely
affect  the  preferences,  special  rights  or powers  of the  Preferred  Stock;
provided,  however,  that any increase in the authorized  preferred stock or the
creation and issuance of any other series of preferred stock ranking on a parity
with or junior to the  Preferred  Stock  shall not be deemed to  materially  and
adversely affect such preferences, special rights or powers.

     5. Liquidation Rights. The Preferred Stock shall have liquidation rights as
set forth in this  paragraph  5, which  rights are pari passu with the rights of
any  outstanding  shares of the Company's  Series C 8% Convertible  Exchangeable
Preferred  Stock.  Upon  the  dissolution,  liquidation  or  winding  up of  the
Corporation, whether voluntary or involuntary, the holders of the shares of this
series of  Preferred  Stock shall be entitled to receive,  before any payment or
distribution  of the assets of the  Corporation  or  proceeds  thereof  (whether
capital or surplus)  shall be made to or set apart for the holders of the Common
Stock or any other class or series of stock ranking junior to the shares of this
series of Preferred Stock upon liquidation, the amount of One Dollar and Fifteen
Cents  ($1.15)  per  share,  plus a sum equal to all  dividends  on such  shares
(whether or not earned or  declared)  accrued and unpaid  thereon to the date of
final  distribution,  but such  holders  shall not be  entitled  to any  further
payment. If, upon any liquidation, dissolution or winding-up of the Corporation,
the assets of the  Corporation,  or proceeds  thereof,  distributable  among the
holders  of shares  of the  Preferred  Stock  and any  other  class or series of
preferred stock ranking on a parity with the Preferred Stock as to payments upon
liquidation,  dissolution or winding-up shall be insufficient to pay in full the
preferential amount foresaid,  then such assets or the proceeds thereof shall be
distributed among such holders ratably in accordance with the respective amounts
which would be payable on such shares if all amounts  payable  thereon were paid
in full. For the purposes of this paragraph 5, the voluntary  sale,  conveyance,
lease,  exchange or transfer  (for cash,  shares of stock,  securities  or other
consideration)  of all or  substantially  all  the  property  or  assets  of the
Corporation  to, or a consolidation  or merger of the  Corporation  with, one or
more corporations  (whether or not the Corporation is the corporation  surviving
such  consolidation  or  merger)  shall  not  be  deemed  to  be a  liquidation,
dissolution or winding-up, voluntary or involuntary.

     6.     Registration Rights.

     (a)  Registration  on Request.  Upon the  written  request of any holder or
holders of at least fifty-one percent (51%) in the aggregate number of shares of
the  Preferred  Stock  and/or  shares of Common  Stock  ("Shares")  issued  upon
conversion of such Preferred  Stock  (provided that in computing such 51% amount
the number of shares of  Preferred  Stock and  Common  Stock  shall be  weighted
proportionately  taking into account the Conversion  Ratio with respect to which
such shares of Common Stock were issued upon  conversion),  which  request shall
state the  intended  method of  disposition  by such holder or holders and shall
request that the Company effect the  registration of all or part of such Shares,
or the Shares  issuable upon the  conversion of such Preferred  Stock,  or both,
under the  Securities  Act of 1933,  as amended  (the"Act"),  the  Company  will
promptly give written  notice of such requested  registration  to all holders of
outstanding  Preferred Stock and Shares, and thereupon will use its best efforts
to effect the registration under the Act of:

     (i) the Shares which the Company has been so  requested  to  register,  for
disposition in accordance with the intended method of disposition stated in such
request, and

     (ii) all other  outstanding  Shares, or Shares issuable upon the conversion
of  Preferred  Stock,  the  holders  of which  shall have made  written  request
(stating the intended  method of disposition of such securities by such holders)
to the  Company  for  registration  thereof  within  thirty  (30) days after the
receipt of such written notice from the Company,  all to the extent requisite to
permit the  disposition  (in  accordance  with the intended  methods  thereof as
aforesaid)  by the  holders of the Shares so  registered  and to  maintain  such
registration  in  effect  for a  period  of  twenty-four  (24)  months  from the
effective date of such registration statement;  provided, that the Company shall
not be required to register or use its best  efforts to effect any  registration
of Shares under the Act pursuant to this  paragraph  6(a) more than once. In the
event that, as a result of such  registration,  another  person with  incidental
registration  rights  granted by the company  requests that the Company  include
securities of such person in such registration,  such request will not result in
a  reduction  in the  number  of  securities  of the  holder or  holders  of the
Preferred Stock and/or Shares to be included in such registration.

     The Company shall have no obligation to register or use its best efforts to
effect any  registration  of Shares under the Act  pursuant to this  paragraph 6
which  would be in  conflict  with the  obligations  of any holder or holders of
Preferred Stock and/or Shares under any  confidentiality  agreement between such
holder or holders and the Company  entered into in connection  with the offering
of the Preferred Stock to such holder or holders.

          (b)  Incidental  Registration.  If the Company at any time proposes to
register  any of its  securities  under  the Act  (otherwise  than  pursuant  to
paragraph 6(a) and other than a  registration  on Form S-8, or the form, if any,
which  supplants  such Form),  it will at such time give  written  notice to all
holders of outstanding Preferred Stock and Shares of its intention to do so and,
upon the written  request of any such holder made within  thirty (30) days after
the receipt of any such notice (which request shall specify the Shares  intended
to be disposed of by such holder and state the  intended  method of  disposition
thereof),  the Company will use its best  efforts to cause all such  outstanding
Shares,  or Shares issuable upon the conversion of Preferred  Stock, the holders
of which shall have so requested  the  registration  thereof,  to be  registered
under the Act to the extent  requisite to permit the  disposition (in accordance
with the intended  methods  thereof as aforesaid)  of the Shares so  registered;
provided  that,  if in the good faith  judgment of the managing  underwriter  or
underwriters  of a then proposed  public  offering of the Company's  securities,
such  registration  of such Shares would  materially  and adversely  affect such
public offering, then in such event the number of Shares and other securities to
be registered by the Company shall each be proportionally reduced to such number
as shall be  acceptable  to the  managing  underwriter,  subject to Section 6(a)
above.

     (c) Registration Procedures. If and whenever the Company is required to use
its best efforts to effect or cause the registration of any Shares under the Act
as provided in this paragraph 6, the Company will, as expeditiously as possible:

     (i)  prepare  and  file  with  the  Securities   and  Exchange   Commission
(the"Commission")  a registration  statement with respect to such Shares and use
its best efforts to cause such registration statement to become effective;

     (ii) prepare and file with the Commission  such  amendments and supplements
to such registration  statement and the prospectus used in connection  therewith
as may be  necessary  to keep such  registration  statement  effective  for such
period not exceeding  twenty-four  (24) months from the  effective  date of such
registration  statement as may be necessary to comply with the provisions of the
Act with respect to the  disposition of all Shares covered by such  registration
statement  during  such  period  in  accordance  with the  intended  methods  of
disposition  by the seller or  sellers  thereof  set forth in such  registration
statement;

     (iii)  furnish to each  seller of such Shares such number of copies of such
registration  statement and of each such  amendment and  supplement  thereto (in
each case  including  all  exhibits),  such  number of copies of the  prospectus
included in such registration  statement (including each preliminary  prospectus
and, if any seller shall so request, a summary  prospectus),  in conformity with
the  requirements  of the Act,  and such  other  documents,  as such  seller may
reasonably request in order to facilitate the disposition of the Shares owned by
such seller;

     (iv) use its best  efforts to  register or qualify  such Shares  covered by
such registration statement under such other securities or blue sky laws of such
jurisdictions  as each seller shall  reasonably  request and as agreed to by the
Corporation,  and do any and all other acts and things  which may be  reasonably
necessary or advisable to enable such seller to consummate  the  disposition  in
such jurisdictions of the Shares owned by such seller; and

     (v) notify  each  seller of any such  Shares  covered by such  registration
statement,  at any time when a  prospectus  relating  thereto is  required to be
delivered  under the Act within the period  mentioned in subdivision (b) of this
paragraph  6(c),  of the  happening  of any  event  as a  result  of  which  the
prospectus included in such registration  statement, as then in effect, includes
an untrue  statement  of a  material  fact or omits to state any  material  fact
required to be stated  therein or necessary to make the  statements  therein not
misleading in the light of the circumstances  then existing,  and at the request
of any such seller  prepare and  furnish to such seller a  reasonable  number of
copies of a supplement to or an amendment of such prospectus as may be necessary
so  that,  as  thereafter  delivered  to the  purchasers  of such  Shares,  such
prospectus  shall not include an untrue  statement of a material fact or omit to
state a material  fact  required to be stated  therein or  necessary to make the
statements  therein  not  misleading  in the  light  of the  circumstances  then
existing.

     (d)  Registration   Expenses.   All  expenses  incident  to  the  Company's
performance  of  or  compliance  with  this  paragraph  6,  including,   without
limitation,  all  registration  and filing fees,  fees and expenses of complying
with securities or blue sky laws,  printing  expenses and fees and disbursements
of counsel for the Company and of independent pubic  accountants,  but excluding
underwriting  commissions and discounts,  the fees of any counsel engaged by the
holder or holders,  and any filing  fees  associated  with  shares of  Preferred
Stock, but not Common Stock, being listed with a national securities exchange or
quoted on the NASDAQ National Market System or Small Cap Market,  shall be borne
by the Company.

     (e) Indemnification.

               (i) In the event of any  registration of any Shares under the Act
pursuant to this paragraph 6, the Company will, to the extent  permitted by law,
indemnify  and hold harmless the seller of such Shares and each  underwriter  of
such  securities  and each other  person,  if any, who  controls  such seller or
underwriter within the meaning of the Act, against any losses, claims,  damages,
or  liabilities,  joint or  several,  to which  such  seller or  underwriter  or
controlling  person may become subject,  under the Act or otherwise,  insofar as
such losses,  claims,  damages,  or liabilities (or actions in respect  thereof)
arise  out of or are based  upon (x) any  untrue  statement  or  alleged  untrue
statement of any material fact contained,  on the effective date thereof, in any
registration  statement under which such  securities  were registered  under the
Act, any preliminary  prospectus or final prospectus  contained therein,  or any
amendment or  supplement  thereto,  or (y) any  omission or alleged  omission to
state therein a material fact required to be stated therein or necessary to make
the  statements  therein not  misleading;  and the Company will  reimburse  such
seller and each such underwriter and each such controlling  person for any legal
or  any  other  expenses   reasonably   incurred  by  them  in  connection  with
investigating or defending any such loss, claim, damage,  liability,  or action,
provided  that the  Company  shall not be liable in any such case to the  extent
that any such loss,  claim,  damage, or liability arises out of or is based upon
an untrue  statement or alleged untrue statement or omission or alleged omission
made in such  registration  statement,  any such preliminary  prospectus,  final
prospectus,  amendment or supplement  in reliance  upon and in  conformity  with
written information furnished to the Company through an instrument duly executed
by such seller or underwriter specifically for use in the preparation thereof.

     (ii) The Company may require, as a condition to including any Shares in any
registration  statement filed pursuant to paragraph 6(c), that the Company shall
have received an undertaking  satisfactory to it from the prospective  seller of
such Shares and from each  underwriter  of such Shares,  to  indemnify  and hold
harmless  (in the same manner and to the same  extent as set forth in  paragraph
6(e)(i)) the Company,  each director of the Company, each officer of the Company
who shall sign such  registration  statement  and any person  who  controls  the
Company within the meaning of the Act, with respect to any statement or omission
from such registration statement, any preliminary prospectus or final prospectus
contained therein,  or any amendment or supplement thereto, if such statement or
omission was made in reliance  upon and in conformity  with written  information
furnished to the Company  through an instrument  duly executed by such seller or
underwriter  specifically  for  use  in the  preparation  of  such  registration
statement, preliminary prospectus, final prospectus, amendment, or supplement.

     (iii)  Promptly  after  receipt  by an  indemnified  party of notice of the
commencement  of any  action  involving  a claim  referred  to in the  preceding
subparagraphs of this paragraph 6(e), such indemnified party will, if a claim in
respect thereof is to be made against an indemnifying party, give written notice
to the latter of the  commencement of such action,  provided that the failure of
any indemnified  party to give notice as provided  therein shall not relieve the
indemnifying  party of its obligations under the preceding  subdivisions of this
paragraph 6(e). In case any such action is brought against an indemnified party,
the  indemnifying  party will be  entitled to  participate  in and to assume the
defense thereof, jointly with any other indemnifying party similarly notified to
the  extent  that it may wish,  with  counsel  reasonably  satisfactory  to such
indemnified  party,  and  after  notice  from  the  indemnifying  party  to such
indemnified  party  of  its  election  so to  assume  the  defense  thereof  the
indemnifying party will not be liable to such indemnified party for any legal or
other  expenses  subsequently  incurred  by the  latter in  connection  with the
defense  thereof.  No  indemnifying  party,  in the defense of any such claim or
litigation, shall, except with the consent of each indemnified party, consent to
entry of any judgment or enter into any settlement  which does not include as an
unconditional  term  thereof  the giving by the  claimant or  plaintiff  to such
indemnified  party of a release  from all  liability in respect to such claim or
litigation.

     7.     Redemption Rights.

          (a) Company's  Redemption Option.  Except for any redemption which the
Company would be prohibited  from effecting  under  applicable law, and provided
the shares of  Preferred  Stock of a holder have not earlier  been  converted in
accordance  with the  provisions  hereof,  the shares of Preferred  Stock may be
redeemed by the Company,  in whole or in part, at the option of the Company upon
written  notice by the  Company to the  holders of  Preferred  Stock at any time
after  December 1, 2001,  in the event that the  Preferred  Stock of one or more
holders has not been  converted  pursuant to the terms  hereof on or before such
date.  The Company  shall redeem each share of  Preferred  Stock of such holders
within  thirty (30) days of the  Company's  delivery of the above notice to such
holders and such holders shall surrender the  certificate(s)  representing  such
shares of Preferred Stock. For any partial  redemptions the Company shall redeem
shares in proportion to the number of shares held by each holder. The redemption
amount shall be One Dollar and  Seventy-five  Cents  ($1.75) per share,  plus in
each case  accrued and unpaid  dividends  thereon to the date of payment of such
amount (the total sum so payable on any such redemption being herein referred to
as the"redemption price").

     (b) Redemption Notice.  Notice of any redemption pursuant to this paragraph
7 shall be mailed to the party or parties required to receive such notice at the
principal  office or  residence  address  for such party or  parties.  Each such
notice shall  state:  (1) the  election of the  redemption  option and the facts
which give rise to such option;  and (2) the number of shares of Preferred Stock
which are being elected to be redeemed. From and after the date of the Company's
payment of the  redemption  price to such holder or holders in  accordance  with
such  redemption  notice  (the"redemption   date"),   notwithstanding  that  any
certificates for such shares shall not have been  surrendered for  cancellation,
the shares represented thereby shall no longer be deemed outstanding, the rights
to receive dividends and distributions  shall cease to accrue from and after the
redemption  date,  and all  rights of such  holder or  holders  of the shares of
Preferred Stock as a stockholder of the Corporation with respect to such shares,
shall cease and terminate.  8. Special rights.  So long as, but only so long as,
the shares of  Preferred  Stock are held by WEDGE  Energy  Services,  L.L.C.,  a
Delaware  limited  liability  company  ("WEDGE"),  or by an  affiliate  of WEDGE
(collectively  "Holder"), the shares of Preferred Stock shall have the following
special rights:

          (a)     Right of Participation.

     (i) Grant of Right of Participation. The Company hereby grants the Holder a
right of participation  to participate in any additional  equity offerings which
the Company may offer, up to the Holder  Percentage (as defined  below),  on the
following  terms and  conditions.  In the event that the Company has  received a
bona fide offer  (which the  Company  desires  to  accept)  with  respect to the
issuance of any equity securities (including,  without limitation, any common or
preferred stock, any options  (excluding the Company's 1993 Stock Option Plan or
any future  employee stock option plan approved by the Company's  shareholders),
warrants,  rights, unsecured convertible notes, convertible debentures, or other
convertible  securities),  the Company  shall  immediately  give written  notice
thereof (the  "Notice") to the Holder of the Preferred  Stock.  The Notice shall
state  the name of the party  proposing  to  provide  the  offering  and all the
pertinent  terms and conditions of such  offering.  This right shall expire upon
the later to occur of the  following:  (a) the  conversion  by the Holder of the
Preferred Stock into Common Stock,  or (b) the tenth  anniversary of the date of
the filing of this Statement.

     (ii) Procedure.  The Holder shall have fourteen (14) days from the date the
Notice  was given to  indicate  to the  Company,  in  writing,  that the  Holder
undertakes to  participate  in the offering  under the terms and  conditions set
forth in the Notice.  If the Holder  undertakes to participate in such offering,
then the  Company  shall be  obligated  to accept such  participation  up to the
Holder  Percentage upon the terms and conditions set forth in the Notice and the
parties  shall use their  best  efforts  to enter  into a  definitive  agreement
relating to such offering.  In the event that the Holder declines to participate
in such offering,  the Company shall have the right to accept such offering from
the third party  without  participation  by the Holder  provided that it does so
upon the terms and  conditions  set forth in the Notice.  In the event that such
offering is not consummated within sixty (60) days after the date the Notice was
given,  the Company shall not consummate  such offering  without again complying
with this subparagraph 8(a)(ii).

     (iii) Holder Percentage.  For purposes hereof, the term "Holder Percentage"
shall mean that  percentage  calculated,  on a fully  diluted  basis,  as if the
Holder had (a)  converted the  Preferred  Stock into Common Stock,  which number
shall constitute the numerator, and (b) divided by the denominator,  which shall
be equal to the total number of shares of Common Stock issued and outstanding as
of such date,  plus (i) that number of shares of Common Stock  issuable upon the
conversion  of all  convertible  securities of the Company,  including,  without
limitation,  the Preferred Stock, and (ii) that number of shares of Common Stock
issuable  upon the exercise of all options and warrants  utilizing the "treasury
method" as of such date.  Under the treasury  method,  only shares issuable upon
the  exercise  of "in the money"  options and  warrants  are  considered  in the
calculation  and the net  dilution is that number of shares  issuable  upon such
exercise net of that number of shares which could have been  purchased  with the
proceeds from the exercise of the options and warrants at the then market price.
For example, assuming 100,000 options are outstanding at a strike price of $1.00
per share and that the  market  price of the  Common  Stock is $2.50 per  share,
under the treasury  method,  the proceeds from the exercise of the options would
equal $100,000 and such proceeds would purchase 40,000 shares of Common Stock at
the market price of $2.50 per share.  The net dilution is 60,000  shares,  which
number of shares is utilized in the calculation of the Holder  Percentage  under
the above formula.

          (b) Restriction on Payment of Cash Dividends and Interest. The Company
agrees that so long as the Holder owns shares of Preferred Stock representing at
least ten percent (10%) of the shares of capital stock of the Company on a fully
diluted  basis  utilizing  the  "treasury  method" as described in  subparagraph
8(a)(iii) above, it shall not pay any cash dividends or any interest accruals on
any equity security or any debt security (excluding any Superior Indebtedness as
defined in that certain Debenture Agreement dated December 10, 1999, between the
Company and WEDGE (the "Debenture Agreement") on file at the Company's principal
office),  in  existence  as of the date hereof or created  hereafter  unless and
until the Company's earnings before deduction of interest,  taxes,  depreciation
and  amortization  ("EBITDA")  for the six (6) months ended with the quarter for
the last  quarterly  report  which the  Company is  required to furnish to WEDGE
under  Section  4.01  of the  Debenture  Agreement  are  more  than  125% of the
Company's  obligations  for all  dividends  and  interest due and payable on all
outstanding securities of the Company as of such time.

     (c) Prohibition  Against Capital  Expenditures.  The Company agrees that so
long as Holder owns shares of Preferred Stock  representing at least ten percent
(10%) of the shares of capital  stock of the  Company on a fully  diluted  basis
utilizing the "treasury  method" as described in subparagraph  8(a)(iii)  above,
the Company will not incur, or commit to incur, any capital  expenditures of any
kind or nature  in  excess  of  $50,000  without  the  approval  by the Board of
Directors of the Company,  and in addition,  the Company agrees that,  until the
Company  has  expended  the  $2,500,000  in  proceeds  from the  issuance of the
Debenture, from the date hereof there shall be no capital expenditures in excess
of $50,000 without the affirmative written consent of WEDGE or its affiliate who
is then the Holder of the Debenture or any security convertible thereto.

     9.  Exclusion of Other Rights.  Except as may otherwise be required by law,
the  shares of  Preferred  Stock  shall not have any  preferences  or  relative,
participating,  optional or other special rights,  other than those specifically
set forth in this  resolution  (as such  resolution  may be amended from time to
time) and in the  Corporation's  Certificate  of  Incorporation.  The  shares of
Preferred Stock shall have no preemptive or subscription rights.

     10. Severability of Provisions.  If any right,  preference or limitation of
the Preferred  Stock set forth in this  resolution  (as such  resolution  may be
amended from time to time) is invalid,  unlawful or incapable of being  enforced
by reason of any rule or law or public policy, all other rights, preferences and
limitations  set forth in this  resolution  (as so  amended)  which can be given
effect  without the invalid,  unlawful or  unenforceable  right,  preference  or
limitation  herein set forth shall be deemed  enforceable and not dependent upon
any other such right, preference or limitation unless so expressed herein.

     11. Status of Reacquired Shares.  Shares of Preferred Stock which have been
issued and reacquired in any manner shall (upon  compliance  with any applicable
provisions of the laws of the State of Texas) have the status of authorized  and
unissued shares of Preferred Stock issuable in series  undesignated as to series
and may be redesignated and reissued.

                                    [END]


<PAGE>



















                                  EXHIBIT "D"

                               VOTING AGREEMENT


<PAGE>



                             VOTING AGREEMENT

     This Voting  Agreement (the  "Agreement")  dated this 10th day of December,
1999 (the "Effective Date"), by and between those certain  individuals set forth
on  Exhibit  A  attached  hereto  and  incorporated   herein  for  all  purposes
(collectively,  the  "Shareholders"  or  individually,  a  "Shareholder"),   TGC
Industries,  Inc., a Texas  corporation  (the  "Corporation"),  and WEDGE Energy
Services, L.L.C., a Delaware limited liability company ("WEDGE").

                               R E C I T A L S :

     A. The Shareholders are the beneficial owners of the shares of common stock
of the corporation  (the "Shares") set forth opposite their respective names set
forth on  Exhibit  A  hereto,  and  each are  entitled  to vote  the  Shares  in
accordance with the terms and conditions provided herein.

     B. In order to facilitate a financing  transaction  between the Corporation
and WEDGE entered into simultaneously herewith, the Shareholders are required to
enter into this Agreement  evidencing their  respective  agreement to vote their
Shares  at each  and  every  special  and or  annual  shareholders'  meeting  in
accordance with the terms provided herein for a slate of directors  nominated by
the  Board  of  Directors  of  the  Corporation,  which  must  include  two  (2)
representatives of WEDGE.

                               A G R E E M E N T S :

     NOW, THEREFORE, in consideration of the covenants and promises contained in
this Agreement and for other good and valuable  consideration recited above, the
receipt and sufficiency of which are hereby  acknowledged,  the parties agree as
follows:

     1.  Limited  Voting   Agreement.   Upon  executing  this   Agreement,   the
Shareholders  will agree to vote the Shares in favor of the  nominations  by the
Board of Directors to serve on the Board of  Directors of the  Corporation.  The
Shareholders  agree to vote in person,  or by proxy,  for the Board of Directors
nominees,  and each understands that without the agreement to do so, WEDGE would
not have  entered  into the  financing  agreement  entered  into  simultaneously
herewith.

     2. Shareholder Representation. The Shareholders and each Shareholder hereby
represent and warrant to the  Corporation  and WEDGE that each is the beneficial
holder  and owner of the  Shares  set forth  opposite  their  name on  Exhibit A
hereto, and as such, each has the unfettered,  absolute and unqualified right to
vote his Shares in the manner prescribed herein.

     3.  Proxy  Statement  Disclosure.   The  Corporation  acknowledges  to  the
Shareholders  that it has entered  into an agreement  with WEDGE  whereby it has
agreed to cause for the  expansion  of the  Board to seven  (7)  members  and to
immediately  cause  the Board of  Directors  to call a  special  meeting  of the
Shareholders  owning any and all capital stock in the Corporation,  and to cause
the names of two (2) WEDGE  nominees to be placed on the ballot for  election by
the Shareholders entitled to vote thereon. Thereafter, the Board of Directors of
the Corporation  has also agreed to  subsequently  cause to be nominated at each
successive  election of directors,  two (2) representatives of WEDGE to serve on
the Board of  Directors  until their  successors  shall have been duly  elected.
Additionally, the Corporation has also agreed that it will cause to be contained
in each proxy  statement  filed  during the  effectiveness  of this  Agreement a
statement   which  will  disclose  the  existence  of  this  Agreement  and  the
requirement of the Shareholders to vote in favor of the two (2) WEDGE nominees.

     4. Filing with  Corporation.  This  Agreement  shall be deposited  with the
Secretary of the  Corporation at its  registered  office and shall be subject to
examination by any  shareholder of the  Corporation  or by any  Shareholder,  in
person or by agent or attorney,  as are the books and records of the Corporation
at any reasonable time for a proper purpose.

     5. Term.  The term of this  Agreement  shall commence on the Effective Date
and shall  terminate  on the  sooner  to occur of (i) WEDGE no longer  owning at
least ten percent  (10%) of the total issued and  outstanding  Shares of capital
stock of the Corporation on a fully diluted basis  calculated in accordance with
the "treasury  method",  (ii)  redemption of the Debenture  held by WEDGE by the
Corporation   in   accordance   with  the  terms  of  any   agreement   executed
simultaneously herewith, or (iii) ten (10) years from the date hereof.

     6.  Assignment,  Sale or  Transfer of Shares of  Shareholders.  Each of the
Shareholders agree that in the event any of them shall decide to sell,  transfer
or convey any or all of his Shares, he shall, prior to doing so, notify WEDGE of
same.  In the  event  there  shall  be a sale,  transfer  or  assignment  to any
affiliate or family member, the Shareholder  agrees that such sale,  transfer or
conveyance  shall not be made  unless the  transferee  shall  agree in  writing,
approved by WEDGE,  to be bound by all terms and  conditions  contained  in this
Agreement.  For purposes of this section,  the term  "affiliate"  shall have the
meaning ascribed to it in the Securities Act of 1933, as amended.

     7. Remedies for Breach of Agreement.  Each of the Shareholders  acknowledge
that in the event such Shareholder shall breach, or intend to breach,  any terms
or  conditions  of this  Agreement,  WEDGE  shall  have  the  right  to seek any
equitable  or legal  remedy it may be  entitled  to  against  such  Shareholder,
including specific performance. In the event WEDGE shall file any action seeking
an equitable remedy,  the parties  acknowledge that if a bond shall be required,
WEDGE shall not be  obligated  to post  greater  than  $1,000 for such bond.  In
addition to the remedies provided for herein, WEDGE shall be entitled to any and
all other remedies that it may be entitled in accordance with applicable law.

     8.   Miscellaneous.

     8.01.  Binding Effect; No Other Agreements or Arrangements.  This Agreement
shall be  binding  upon the  parties  and  their  respective  heirs,  executors,
administrators,  successors,  assigns and legal  representatives.  Each party to
this Agreement hereby  represents and warrants to all other parties that, except
for this  Agreement,  such party has not entered into, or agreed to be bound by,
and will not,  so long as the terms of the  Agreement  remain in  effect,  enter
into,  or agree  to be  bound  by,  any  other  voting  arrangements  or  voting
agreements of any kind with any other person (including a party) with respect to
the Shares, other than this Agreement.

     8.02.  Waiver.  A party's failure to insist on compliance or enforcement of
any provision of this Agreement, shall not affect the validity or enforceability
or constitute a waiver of future  enforcement  of that provision or of any other
provision of this Agreement by that party or any other party.

     8.03. Governing Law;  Jurisdiction.  This Agreement shall in all respect be
subject to,  governed by, and  interpreted  in accordance  with, the laws of the
State of Texas. The parties agree that jurisdiction over any dispute relating to
this  Agreement  shall reside in any court or other  judicial or  quasi-judicial
body such as an arbiter or mediator  that is located  within the State of Texas,
and they hereby consent to such jurisdiction and agree to appear in the State of
Texas with regard to any such dispute.

     8.04. Severability.  The invalidity or unenforceability of any provision of
this  Agreement  shall not effect the  validity or  enforceability  of any other
provision  of this  Agreement,  and this  Agreement  shall be  construed  in all
respect as if such  invalid  or  unenforceable  provision  has never been in the
Agreement.

     8.05. Effectiveness of Voting Agreements. To the extent this Agreement is a
"voting agreement" under Article 2.30B of the Texas Business Corporation Act, it
shall be  effective,  as provided in this  Agreement  or any  extension  of this
Agreement in accordance with Article 2.30B.

     8.06.  Headings;  Execution  in  Counterparts.  The  headings  and captions
contained in this Agreement are for  convenience and shall not control or affect
the meaning or construction  of any provision of this Agreement.  This Agreement
may be executed in any number of counterparts,  each of which shall be deemed to
be  an  original  and  which,  together,  shall  constitute  one  and  the  same
instrument.

     8.07.  Entire  Agreement.  This  Agreement,   including  all  exhibits  and
schedules to this Agreement,  embodies the entire Agreement and understanding of
the parties to this Agreement  with respect to the subject  matter  contained in
this Agreement,  and this Agreement supersedes and replaces all prior agreements
and understandings between the parties concerning such subject matter.

     8.08. Amendments. This Agreement shall not be modified or amended except by
a writing signed by each party.

     8.09. Notices; Shareholder Representative.  Any and all notices required by
this Agreement shall be deemed to be received (i) when  personally  delivered to
the recipient,  (ii) when sent via facsimile,  upon receipt of a confirmation or
acknowledgment of receipt of facsimile transmittal, provided a confirmation copy
is sent by first class mail,  (iii) on the next  business  day after the date of
deposit with an overnight  courier,  or (iv) five (5) days after  postmark  when
deposited with the United States or other foreign  country mail. For purposes of
receiving   notices  and  any  other  purpose   under  this   Agreement  by  the
Shareholders,  each Shareholder,  by his execution hereof, hereby appoints Wayne
Whitener, as his representative (the "Shareholder Representative") for receiving
of notices under this Agreement.  The address of the Shareholder  Representative
is 1304  Summit  Avenue,  Suite  2,  Plano,  Texas  75074.  The  address  of the
Corporation  for notice  purposes is 1304 Summit Avenue,  Suite 2, Plano,  Texas
75074. The address for WEDGE for notice purposes is 1415 Louisiana,  Suite 3000,
Houston, Texas 77002,  Attention:  President,  with a second notice addressed to
1415 Louisiana, Suite 3000, Houston, Texas 77002, Attention: General Counsel.

     8.10.  Attorneys'  Fees.  In the  event  that  any  action,  suit or  other
proceeding  arising  from,  or based on, this  Agreement is brought by any party
against  any  other  party to this  Agreement,  the  prevailing  party  shall be
entitled to recover from the non-prevailing party reasonable attorneys' fees and
costs in connection with such action, suit or proceeding.


                         [SIGNATURES ON NEXT PAGE]


<PAGE>



     IN WITNESS  WHEREOF the parties  hereto have executed this  Agreement as of
the date first above written.

                                        TGC INDUSTRIES, INC.

                                        ---------------------------------
                                        Printed Name:  __________________
                                        Title: __________________________

                                        SHAREHOLDERS:

                                        ---------------------------------
                                        Allen McInnes

                                        ---------------------------------
                                        Wayne Whitener

                                        ---------------------------------
                                        Herbert Gardner

                                        ---------------------------------
                                        William J. Barrett

                                        ---------------------------------
                                        Edward L. Flynn

                                        WEDGE ENERGY SERVICES, L.L.C.

                                        Printed Name: ___________________
                                        Title: __________________________


<PAGE>




                                EXHIBIT A

                          TGC Industries, Inc.
                  Shareholders' Ownership Percentage

                       as of December 1, 1999

     SHAREHOLDERS                           PREFERRED             COMMON

     Allen McInnes                            63,162              335,844

     Wayne Whitener                            3,000               10,317

     Herbert Gardner                          47,500              155,259

     William J. Barrett                       72,500              260,910

     Edward L. Flynn                         125,131              230,309

          Total Shareholders' Shares:        311,393              992,639

     Total Capital Stock Outstanding       1,115,750            2,253,184

     Percent of Ownership                      27.9%                 44.1%

     Total Common Shares Outstanding       2,253,184

     Total Preferred Shares Outstanding    1,115,750

          Total Outstanding Shares:        3,368,934

Total Number of Shares Held

by Shareholders                            1,303,932

Percent Held by Shareholders                   38.7%


<PAGE>






























                                   EXHIBIT "E"

                 Form of Opinion of Law, Snakard & Gambill, P.C.


<PAGE>












                            December 10, 1999

WEDGE Group, Incorporated
WEDGE Energy Services, L.L.C.
WEDGE International Tower
1415 Louisiana, Suite 3000

Houston, Texas 77002

          Re:     $2,500,000.00 Debenture Issued by TGC Industries, Inc.
                  to WEDGE Energy Services, L.L.C.

Ladies and Gentlemen:

          We have acted as counsel to TGC Industries,  Inc. ("Company" or "TGC")
in connection with the issuance by TGC of its $2,500,000 principal amount 8 1/2%
Convertible  Subordinated  Debenture,  Series B (the"Debenture") to WEDGE Energy
Services,  L.L.C.  ("Holder")  in  accordance  with the  terms  of that  certain
Debenture Agreement dated December 10, 1999, between the Company and Holder (the
"Debenture  Agreement").  This  opinion  letter is being  delivered to Holder in
accordance with Section 8.14 of that certain Debenture  Purchase Agreement dated
December 10, 1999, between the Company and Holder (the "Purchase Agreement").

          In reaching the conclusions  expressed in this opinion letter, we have
examined  originals or copies of each of the  following  documents  (hereinafter
collectively referred to as the"Debenture Documents"):

     (a) The  Debenture  Agreement  and the form of the  Debenture  attached  as
Exhibit "A" thereto;

     (b)     The Purchase Agreement and the Exhibits thereto; and

     (c) That certain  Voting  Agreement  dated  December 10, 1999,  between the
Company,  the Holder, and those certain shareholders of the Company as set forth
in Exhibit "A" thereto.

The capitalized terms used in this opinion letter which are not defined above or
elsewhere  herein  shall have the same  meanings  as  provided  therefor  in the
Debenture Agreement unless the context hereof otherwise requires or provides.

          In addition to the Debenture  Documents,  we have also reviewed  those
additional documents necessary to render the opinion herein,  including, but not
limited to Company records,  Board minutes and  resolutions,  and public filings
with any state or governmental  authority.  We have also been furnished with and
have examined such other  instruments,  documents,  and  certificates  of public
officials and others, and have made such inquiry of Company,  and have made such
other  investigations  as we have deemed necessary as the basis for the opinions
herein  expressed.  As to questions of fact material to this opinion letter,  we
have relied upon statements or certificates of public  officials and of Company,
and such other facts known to us, but we have made no independent  investigation
with regard to such matters,  including without  limitation,  the warranties and
representations made by Company in the Debenture Documents.

          All opinions  contained  herein which relate to the issue of usury are
expressly limited to an analysis of whether the Debenture Documents, as written,
will be subject to a defense,  claim or setoff as a result of an  interpretation
that the Holder has contracted  for a usurious rate of interest.  Each and every
opinion  given  herein  is  expressly  limited  to the  issues  relating  to the
contracting  for  usurious  amounts of interest and the charging or receiving in
compliance  with the terms of the  Debenture  Documents  of usurious  amounts of
interest,  as  opposed to the  charging  or  receiving  of  usurious  amounts of
interest in contravention of the terms of the Debenture Documents.

          In reaching the conclusions  expressed in this opinion letter, we have
also  assumed  that (a) all  signatures  on all  documents  submitted  to us are
genuine;  (b) all  documents  submitted  to us as  originals  are  accurate  and
complete;  (c) all  documents  submitted  to us as copies  are true and  correct
copies of the originals thereof; (d) all information submitted to us is accurate
and complete (e) the  Debenture  Documents are governed by the laws of the State
of Texas and the laws of the United  States of  America  and that a court of the
State of Texas or a federal court sitting in Texas would apply the domestic laws
of such state and any applicable federal laws to determine whether the Debenture
or any of the other Debenture Documents is usurious; (f) no fees, sums, or other
benefits,  whether direct or indirect, have been paid or received or are, or may
be, payable to or receivable by Holder except as expressly  mentioned  herein or
in the  Debenture  Documents;  (g)  there  are not,  nor  shall  there  be,  any
compensating   balances,   deposits,  or  other  funds  of  Company  pledged  or
hypothecated  by  Company  as  security  for  the  Debenture  or as any  form of
compensation,  whether  direct or  indirect,  to Holder in  connection  with the
Debenture other than as stated in the Debenture Documents,  and any and all fees
paid by Company to Holder  would be  construed  as charges  bearing a reasonable
relationship  to the cost or risk of the service or  accommodation  for which it
was charged, and not as a charge for the use, forbearance or detention of money;
in this  connection,  we have no knowledge of, nor have we made any  independent
investigation  of, any fees other than as specified in the Debenture  Documents,
and the opinions  expressed herein are qualified in their entirety by the effect
that any such fees may have on the  opinions  herein  stated;  (h)  Holder  will
enforce its rights  under the  Debenture  Documents  in  circumstances  and in a
manner  which are  commercially  reasonable;  (i) all  applicable  and  existing
statutes  and  regulations  are  valid  and  constitutional;  (j) all  Debenture
Documents to which Holder is a party have been duly  authorized,  executed,  and
delivered  by  Holder;  and  (k)  the  Debenture  Documents  fully  express  the
agreements of the parties thereto.

     You are specifically advised that the foregoing  assumptions may or may not
be valid,  and are not  expressed  herein as  statements  of fact,  law,  or our
opinion thereon;  though we have no knowledge that such assumptions are invalid.
Please be further advised that we assume no responsibility to you whatsoever for
the  effect,  if any, of a  determination  that such  assumptions,  or any other
assumptions  contained  herein,  were  erroneous  either when made or at a later
date,  except if we had knowledge  that any assumption was erroneous at the time
made.

          Based solely on our review of the  Debenture  Documents  and the other
instruments,  documents and certificates  referenced  above, but subject to, and
limited by, the  qualifications and assumptions set forth in this letter, we are
of opinion that, as of the date hereof:

     1.  Organization,  Standing;  Powers.  The  Company is a  corporation  duly
organized and validly  existing and in good standing under the laws of the State
of Texas and has all  requisite  corporate  power and  authority to carry on its
business as now  conducted  and  proposed to be  conducted;  the Company has all
requisite  corporate power and authority to enter into the Debenture  Documents,
to issue  the  Debenture  and the  shares of  capital  stock  issuable  upon the
conversion  thereof  and to  carry  out the  provisions  and  conditions  of the
Debenture Documents. The Company is duly qualified and authorized to do business
and is in good  standing  as a  foreign  corporation  in all  states  where  the
ownership  of property or the nature of the business  transacted  by the Company
makes such qualification necessary.

     2.  Capitalization.  The Company has  25,000,000  authorized  shares of its
Common Stock and  4,000,000  authorized  shares of its  preferred  stock.  As of
December 1, 1999,  the Company had 2,253,184  issued and  outstanding  shares of
Common Stock,  1,115,750  issued and  outstanding  shares of preferred stock and
31,944  treasury  shares.  As of December 1, 1999, the Company had granted stock
options  which,  if all were  exercised,  would equal  179,831  shares of Common
Stock.  As of  December 1, 1999,  the  Company  had issued one or more  warrants
which, if all are exercised,  will in the aggregate  equal  1,136,574  shares of
Common  Stock.  Additionally,  as of December 1, 1999,  excluding  the shares of
Common Stock to be received by Holder upon its election to convert the Debenture
to Common Stock,  there are 2,789,375 shares of Common Stock to be issued if all
existing preferred  stockholders were to elect to convert their shares to Common
Stock.

     3.  Authorization;  Binding Agreement.  All corporate action on the part of
the Company necessary for the authorization, execution, delivery and performance
by  Company  of  the  Debenture  Documents  and  for  the  consummation  of  the
transactions  contemplated therein, and for the authorization,  offer, issuance,
sale and delivery of the Debenture,  has been taken. The Debenture Documents are
the valid and binding obligation of the Company,  enforceable in accordance with
their  terms.  The  Debenture  Documents  have been or will be, on or before the
applicable  Closing  Date,  duly executed and delivered on behalf of the Company
and  constitute,  on or before the  applicable  closing date,  legal,  valid and
binding  obligations  of  the  Company  enforceable  in  accordance  with  their
respective terms.

     4. No Conflicts with Organizational Documents and Material Agreements.  The
execution,  delivery and  performance by the Company of the Debenture  Documents
and compliance  therewith,  including  delivery of the shares of common stock in
the event of conversion,  and the offer,  issuance and delivery of the Debenture
will not result in any  violation of and will not conflict  with, or result in a
breach of any of the terms of, or  constitute  a default  under,  the  Company's
Articles of Incorporation, as amended, Bylaws, as amended, or, to our knowledge,
any mortgage,  indenture,  agreement,  instrument,  judgment,  writ, injunction,
decree or order to which the Company is a party or by which it is bound.

     5.  No  Consents.  No  consent,  license,  approval,  authorization,  prior
disclosure,  qualification,  exemption, franchise,  designation, permit or order
of, notice to or declaration or filing with, any third party, including, without
limitation,  any governmental  entity,  is required in connection with the valid
execution, delivery and performance by the Company of the Debenture Documents or
the offer,  issuance and  delivery of the  Debenture  pursuant to the  Debenture
Documents or the consummation of any other  transactions  contemplated  thereby,
except for the consent of the holders of the  Company's 8% Series C  Convertible
Exchangeable  Preferred  Stock as  referenced  in  Section  6.1 of the  Purchase
Agreement.

     6.  Debenture  Not  Usurious.  The  extension of credit as reflected in the
Debenture  Documents,  the prepayment  provision set forth in Article III of the
Debenture  Agreement,  and the conversion provision set forth in Article VIII of
the Debenture  Agreement are not usurious under the applicable laws of the State
of Texas or the United States of America.

          The  opinions  expressed  herein  are  qualified  to the  extent  that
enforceability  of the  Debenture  Documents may be limited by or subject to (a)
the rights of the United  States under Federal Tax Lien Act of 1966, as amended;
(b)  the  effect  of  liquidation,   conservatorship,   insolvency,  bankruptcy,
fraudulent or preferential transfer or conveyance,  reorganization,  moratorium,
and other  similar  debtor relief laws of general  application  now or hereafter
affecting the rights of  creditors;  (c) the power of courts to award damages in
lieu of granting equitable remedies;  (d) the provisions of Section 365 of Title
11 of the United  States  Code,  invalidating  any  contract  provision  for the
termination  or  modification  of any right or  obligation  under such  contract
solely  because of a  provision  in such  contract  that is  conditioned  on the
insolvency or financial  condition of the obligor,  the  commencement  of a case
under such Title 11 or the appointment of or taking possession by a trustee in a
case under such Title 11 or by a custodian  for the  commencement  of such case;
and (e) the effect of rules of law governing  specific  performance,  injunctive
relief, and other equitable remedies.  Specifically, we express no opinion as to
whether a court would grant specific  performance or any other equitable  remedy
with respect to the enforcement of any of the Debenture Documents.

          In rendering the opinions  expressed  herein, we express no opinion as
to the enforceability of any provisions of the Debenture Documents which purport
to (a) establish  evidentiary  standards for suits or  proceedings  or restrict,
limit or deny access to courts; (b) waive or release the legal rights,  benefits
or claims of any party (including, without limitation,  Company) in advance; (c)
allow or authorize the delay or omission of  enforcement of any right or remedy;
(d) avoid or ignore  the  doctrines  of  mortgagee-in-possession  or  commercial
reasonableness;  (e) establish  nonculpability for actions taken by or on behalf
of Holder or any other person;  (f) authorize Holder to act as  attorney-in-fact
for Company or any other person;  (g) provide for the appointment of a receiver,
to the extent that appointment of a receiver is governed by applicable statutory
requirements and to the extent any such provision of the Debenture Documents may
not be in compliance  with any statutory  requirements;  or (h) permit Holder to
accelerate  the  maturity  of the  indebtedness  evidenced  and  governed by the
Debenture  Documents  without  notice to Company  and to any  obligor  that is a
signatory  to or  bound  by  the  Debenture  Documents  of  Holder's  intent  to
accelerate such  indebtedness  and notice of acceleration of such  indebtedness.
Enforceability of obligations under the Debenture  Documents may also be limited
by constitutional limitations of notice and due process.

          In rendering the opinions  expressed  herein, we express no opinion as
to (a) the accuracy,  completeness, or fairness of any statements,  information,
representations,  warranties, or financial data included in any of the Debenture
Documents  or  supplied  by  any  person  or  entity  in  connection   with  the
transactions   contemplated  by  the  Debenture   Documents,   and  we  make  no
representations that we have independently verified the accuracy,  completeness,
or fairness of any such statements, information, representations, warranties, or
financial  data;  or (b) the  financial  ability of  Company  to meet  Company's
obligations under the Debenture Documents.  However, we do not have knowledge of
any facts which would render any representation, warranty, agreement or covenant
false, incomplete or misleading.

          In rendering the opinions  expressed  herein, we express no opinion as
to the applicability to the transactions contemplated by the Debenture Documents
of the Securities  Act of 1933,  the Securities  Exchange Act of 1934, the Texas
Securities  Act,  or  any of  the  various  rules  and  regulations  promulgated
thereunder;  and we express no opinion as to the  compliance  by the  parties to
such transaction with such Acts, rules, and regulations.

          The qualification of any opinion or statement herein by the use of the
words"knowledge,""current  actual  knowledge,""known  to  us,""of  which  we are
aware,""to our knowledge" or"to the best of our knowledge" means that during the
course of our  representation  of Company in connection with the issuance of the
Debenture,  no fact or circumstances is known to us or has come to the attention
of the attorneys  directly  involved in the  transactions  or who have regularly
worked on matters  on behalf of the  Company  surrounding  the  issuance  of the
Debenture or entering into the  Debenture  Documents  which give such  attorneys
actual   knowledge  of  the  existence  of  documents  or  facts  so  qualified.
Furthermore,  except  as  otherwise  expressly  set  forth  herein,  we have not
undertaken  any  investigation  to  determine  the  existence or absence of such
documents or facts,  and no inference  as to our  knowledge of the  existence of
such documents or facts should be drawn from the fact of our  representation  of
Company or otherwise.

     We are  licensed to practice  law only in the State of Texas.  This opinion
letter is limited to the laws of the State of Texas and of the United  States of
America,  and to acts or events determined according to such laws and the courts
of the State of Texas and  federal  courts  sitting in Texas,  and we express no
opinion  with respect to the effect of any laws other than the laws of the State
of Texas and the United States of America.

          This opinion  letter is limited to the matters  expressly set forth in
numbered opinion paragraphs 1 through 6, and no opinion is to be inferred or may
be implied beyond the matters expressly so stated.

     We are  furnishing  this opinion letter to Holder solely for the benefit of
Holder and solely for the purpose of complying with Holder's  requirements under
the Purchase Agreement. This is submitted as a legal opinion only of the matters
discussed herein.  This opinion letter may not be used,  circulated,  quoted, or
otherwise  referred to in connection  with any  transaction  other than the Loan
without our prior written  consent,  and may not be relied upon in any manner by
any person,  firm, or entity whatsoever other than Holder and its successors and
assigns  and its legal  counsel.  We  disclaim  any  requirement  to update this
opinion letter subsequent to the date hereof.

                                   Respectfully submitted,

                                   LAW, SNAKARD & GAMBILL,

                                   A Professional Corporation

VER/dc


<PAGE>

























                                EXHIBIT 10.12

                               VOTING AGREEMENT


<PAGE>



                             VOTING AGREEMENT

     This Voting  Agreement (the  "Agreement")  dated this 10th day of December,
1999 (the "Effective Date"), by and between those certain  individuals set forth
on  Exhibit  A  attached  hereto  and  incorporated   herein  for  all  purposes
(collectively,  the  "Shareholders"  or  individually,  a  "Shareholder"),   TGC
Industries,  Inc., a Texas  corporation  (the  "Corporation"),  and WEDGE Energy
Services, L.L.C., a Delaware limited liability company ("WEDGE").

                               R E C I T A L S :

     A. The Shareholders are the beneficial owners of the shares of common stock
of the corporation  (the "Shares") set forth opposite their respective names set
forth on  Exhibit  A  hereto,  and  each are  entitled  to vote  the  Shares  in
accordance with the terms and conditions provided herein.

     B. In order to facilitate a financing  transaction  between the Corporation
and WEDGE entered into simultaneously herewith, the Shareholders are required to
enter into this Agreement  evidencing their  respective  agreement to vote their
Shares  at each  and  every  special  and or  annual  shareholders'  meeting  in
accordance with the terms provided herein for a slate of directors  nominated by
the  Board  of  Directors  of  the  Corporation,  which  must  include  two  (2)
representatives of WEDGE.

                               A G R E E M E N T S :

     NOW, THEREFORE, in consideration of the covenants and promises contained in
this Agreement and for other good and valuable  consideration recited above, the
receipt and sufficiency of which are hereby  acknowledged,  the parties agree as
follows:

     1.  Limited  Voting   Agreement.   Upon  executing  this   Agreement,   the
Shareholders  will agree to vote the Shares in favor of the  nominations  by the
Board of Directors to serve on the Board of  Directors of the  Corporation.  The
Shareholders  agree to vote in person,  or by proxy,  for the Board of Directors
nominees,  and each understands that without the agreement to do so, WEDGE would
not have  entered  into the  financing  agreement  entered  into  simultaneously
herewith.

     2. Shareholder Representation. The Shareholders and each Shareholder hereby
represent and warrant to the  Corporation  and WEDGE that each is the beneficial
holder  and owner of the  Shares  set forth  opposite  their  name on  Exhibit A
hereto, and as such, each has the unfettered,  absolute and unqualified right to
vote his Shares in the manner prescribed herein.

     3.  Proxy  Statement  Disclosure.   The  Corporation  acknowledges  to  the
Shareholders  that it has entered  into an agreement  with WEDGE  whereby it has
agreed to cause for the  expansion  of the  Board to seven  (7)  members  and to
immediately  cause  the Board of  Directors  to call a  special  meeting  of the
Shareholders  owning any and all capital stock in the Corporation,  and to cause
the names of two (2) WEDGE  nominees to be placed on the ballot for  election by
the Shareholders entitled to vote thereon. Thereafter, the Board of Directors of
the Corporation  has also agreed to  subsequently  cause to be nominated at each
successive  election of directors,  two (2) representatives of WEDGE to serve on
the Board of  Directors  until their  successors  shall have been duly  elected.
Additionally, the Corporation has also agreed that it will cause to be contained
in each proxy  statement  filed  during the  effectiveness  of this  Agreement a
statement   which  will  disclose  the  existence  of  this  Agreement  and  the
requirement of the Shareholders to vote in favor of the two (2) WEDGE nominees.

     4. Filing with  Corporation.  This  Agreement  shall be deposited  with the
Secretary of the  Corporation at its  registered  office and shall be subject to
examination by any  shareholder of the  Corporation  or by any  Shareholder,  in
person or by agent or attorney,  as are the books and records of the Corporation
at any reasonable time for a proper purpose.

     5. Term.  The term of this  Agreement  shall commence on the Effective Date
and shall  terminate  on the  sooner  to occur of (i) WEDGE no longer  owning at
least ten percent  (10%) of the total issued and  outstanding  Shares of capital
stock of the Corporation on a fully diluted basis  calculated in accordance with
the "treasury  method",  (ii)  redemption of the Debenture  held by WEDGE by the
Corporation   in   accordance   with  the  terms  of  any   agreement   executed
simultaneously herewith, or (iii) ten (10) years from the date hereof.

     6.  Assignment,  Sale or  Transfer of Shares of  Shareholders.  Each of the
Shareholders agree that in the event any of them shall decide to sell,  transfer
or convey any or all of his Shares, he shall, prior to doing so, notify WEDGE of
same.  In the  event  there  shall  be a sale,  transfer  or  assignment  to any
affiliate or family member, the Shareholder  agrees that such sale,  transfer or
conveyance  shall not be made  unless the  transferee  shall  agree in  writing,
approved by WEDGE,  to be bound by all terms and  conditions  contained  in this
Agreement.  For purposes of this section,  the term  "affiliate"  shall have the
meaning ascribed to it in the Securities Act of 1933, as amended.

     7. Remedies for Breach of Agreement.  Each of the Shareholders  acknowledge
that in the event such Shareholder shall breach, or intend to breach,  any terms
or  conditions  of this  Agreement,  WEDGE  shall  have  the  right  to seek any
equitable  or legal  remedy it may be  entitled  to  against  such  Shareholder,
including specific performance. In the event WEDGE shall file any action seeking
an equitable remedy,  the parties  acknowledge that if a bond shall be required,
WEDGE shall not be  obligated  to post  greater  than  $1,000 for such bond.  In
addition to the remedies provided for herein, WEDGE shall be entitled to any and
all other remedies that it may be entitled in accordance with applicable law.

     8. Miscellaneous.

     8.01.  Binding Effect; No Other Agreements or Arrangements.  This Agreement
shall be  binding  upon the  parties  and  their  respective  heirs,  executors,
administrators,  successors,  assigns and legal  representatives.  Each party to
this Agreement hereby  represents and warrants to all other parties that, except
for this  Agreement,  such party has not entered into, or agreed to be bound by,
and will not,  so long as the terms of the  Agreement  remain in  effect,  enter
into,  or agree  to be  bound  by,  any  other  voting  arrangements  or  voting
agreements of any kind with any other person (including a party) with respect to
the Shares, other than this Agreement.

     8.02.  Waiver.  A party's failure to insist on compliance or enforcement of
any provision of this Agreement, shall not affect the validity or enforceability
or constitute a waiver of future  enforcement  of that provision or of any other
provision of this Agreement by that party or any other party.

     8.03. Governing Law;  Jurisdiction.  This Agreement shall in all respect be
subject to,  governed by, and  interpreted  in accordance  with, the laws of the
State of Texas. The parties agree that jurisdiction over any dispute relating to
this  Agreement  shall reside in any court or other  judicial or  quasi-judicial
body such as an arbiter or mediator  that is located  within the State of Texas,
and they hereby consent to such jurisdiction and agree to appear in the State of
Texas with regard to any such dispute.

     8.04. Severability.  The invalidity or unenforceability of any provision of
this  Agreement  shall not effect the  validity or  enforceability  of any other
provision  of this  Agreement,  and this  Agreement  shall be  construed  in all
respect as if such  invalid  or  unenforceable  provision  has never been in the
Agreement.

     8.05. Effectiveness of Voting Agreements. To the extent this Agreement is a
"voting agreement" under Article 2.30B of the Texas Business Corporation Act, it
shall be  effective,  as provided in this  Agreement  or any  extension  of this
Agreement in accordance with Article 2.30B.

     8.06.  Headings;  Execution  in  Counterparts.  The  headings  and captions
contained in this Agreement are for  convenience and shall not control or affect
the meaning or construction  of any provision of this Agreement.  This Agreement
may be executed in any number of counterparts,  each of which shall be deemed to
be  an  original  and  which,  together,  shall  constitute  one  and  the  same
instrument.

     8.07.  Entire  Agreement.  This  Agreement,   including  all  exhibits  and
schedules to this Agreement,  embodies the entire Agreement and understanding of
the parties to this Agreement  with respect to the subject  matter  contained in
this Agreement,  and this Agreement supersedes and replaces all prior agreements
and understandings between the parties concerning such subject matter.

     8.08. Amendments. This Agreement shall not be modified or amended except by
a writing signed by each party.

     8.09. Notices; Shareholder Representative.  Any and all notices required by
this Agreement shall be deemed to be received (i) when  personally  delivered to
the recipient,  (ii) when sent via facsimile,  upon receipt of a confirmation or
acknowledgment of receipt of facsimile transmittal, provided a confirmation copy
is sent by first class mail,  (iii) on the next  business  day after the date of
deposit with an overnight  courier,  or (iv) five (5) days after  postmark  when
deposited with the United States or other foreign  country mail. For purposes of
receiving   notices  and  any  other  purpose   under  this   Agreement  by  the
Shareholders,  each Shareholder,  by his execution hereof, hereby appoints Wayne
Whitener, as his representative (the "Shareholder Representative") for receiving
of notices under this Agreement.  The address of the Shareholder  Representative
is 1304  Summit  Avenue,  Suite  2,  Plano,  Texas  75074.  The  address  of the
Corporation  for notice  purposes is 1304 Summit Avenue,  Suite 2, Plano,  Texas
75074. The address for WEDGE for notice purposes is 1415 Louisiana,  Suite 3000,
Houston, Texas 77002,  Attention:  President,  with a second notice addressed to
1415 Louisiana, Suite 3000, Houston, Texas 77002, Attention: General Counsel.

     8.10.  Attorneys'  Fees.  In the  event  that  any  action,  suit or  other
proceeding  arising  from,  or based on, this  Agreement is brought by any party
against  any  other  party to this  Agreement,  the  prevailing  party  shall be
entitled to recover from the non-prevailing party reasonable attorneys' fees and
costs in connection with such action, suit or proceeding.


                         [SIGNATURES ON NEXT PAGE]


<PAGE>



     IN WITNESS  WHEREOF the parties  hereto have executed this  Agreement as of
the date first above written.

                                        TGC INDUSTRIES, INC.

                                        /s/ Wayne Whitener

                                        ---------------------------------
                                        Printed Name:  Wayne Whitener
                                        Title:  President

                                        SHAREHOLDERS:

                                        /s/ Allen McInnes

                                        ---------------------------------
                                        Allen McInnes

                                        /s/ Wayne Whitener

                                        ---------------------------------
                                        Wayne Whitener

                                        /s/ Herbert Gardner

                                        ---------------------------------
                                        Herbert Gardner

                                        /s/ William J. Barrett

                                        ---------------------------------
                                        William J. Barrett

                                        /s/ Edward L. Flynn

                                        ---------------------------------
                                        Edward L. Flynn

                                        WEDGE ENERGY SERVICES, L.L.C.

                                        /s/ Bill White

                                        ---------------------------------
                                        Printed Name: Bill White
                                        Title: President


<PAGE>




                                EXHIBIT A

                          TGC Industries, Inc.
                  Shareholders' Ownership Percentage

                       as of December 1, 1999

     SHAREHOLDERS                           PREFERRED             COMMON

     Allen McInnes                            63,162              335,844

     Wayne Whitener                            3,000               10,317

     Herbert Gardner                          47,500              155,259

     William J. Barrett                       72,500              260,910

     Edward L. Flynn                         125,131              230,309

          Total Shareholders' Shares:        311,393              992,639

     Total Capital Stock Outstanding       1,115,750            2,253,184

     Percent of Ownership                      27.9%                 44.1%

     Total Common Shares Outstanding       2,253,184

     Total Preferred Shares Outstanding    1,115,750

          Total Outstanding Shares:        3,368,934

Total Number of Shares Held

by Shareholders                            1,303,932

Percent Held by Shareholders                   38.7%


<PAGE>













                                EXHIBIT 10.13

                            1999 Stock Option Plan

                                     of

                             TGC Industries, Inc.


<PAGE>





                             Table of Contents

                                                                       Page

Article I:    Definitions
              Sec. 1:1.     Act
              Sec. 1:2.     Affiliates
              Sec. 1:3.     Agreement

              Sec. 1:4.     Board of Directors
              Sec. 1:5.     Code
              Sec. 1:6.     Committee
              Sec. 1:7.     Eligible Individuals
              Sec. 1:8.     Fair Market Value
              Sec. 1:9.     Holder
              Sec. 1:10.     Incentive Stock Options
              Sec. 1:11.     Nonstatutory Stock Options
              Sec. 1:12.     Options
              Sec. 1:13.     Stock

Article II:   Stock and Maximum Number of Shares Subject to the Plan
              Sec. 2:1.     Description of Stock and Maximum Shares Allocated
              Sec. 2:2.     Restoration of Shares

Article III:  Administration of the Plan
              Sec. 3:1.     Stock Option Committee
              Sec. 3:2.     Duration, Removal, Etc.
              Sec. 3:3.     Meetings and Actions of Committee
              Sec. 3:4.     Committee's Powers

Article IV:   Eligibility and Participation
              Sec. 4:1.     Eligible Individuals
              Sec. 4:2.     No Right to Option

Article V:    Grant of Options and Certain Terms of the Agreements
              Sec. 5:1.     Determination of Eligible Individuals
              Sec. 5:2.     Date of Grant
              Sec. 5:3.     Stock Option Agreement
              Sec. 5:4.     Forfeiture of Stock
              Sec. 5:5.     Cash Awards

Article VI:   Terms and Conditions of Options
              Sec. 6:1.     Number of Shares
              Sec. 6:2.     Exercise Price

              Sec. 6:3.     Medium and Time of Payment, Method of Exercise,
                            and Withholding Taxes

              Sec. 6:4.     Terms, Time of Exercise, and Transferability of
                            Options

              Sec. 6:5.     Limitation on Aggregate Value of Shares That May
                            Become First Exercisable During Any Calendar Year
                            Under an Incentive Stock Option

              Sec. 6:6.     Adjustments Upon Changes in Capitalization,
                            Merger, Etc.

              Sec. 6:7.     Rights as a Shareholder

              Sec. 6:8.     Modification, Extension, and Renewal of Options
              Sec. 6:9.     Furnish Information
              Sec. 6:10.    Obligation to Exercise; Termination of Employment
              Sec. 6:11.    Agreement Provisions

Article VII:  Duration of Plan
Article VIII: Amendment of Plan

Article IX:   General

              Sec. 9:1.     Application of Funds

              Sec. 9:2.     Right of Company and Affiliates to Terminate
                            Employment

              Sec. 9:3.     No Liability for Good Faith Determinations
              Sec. 9:4.     Information Confidential
              Sec. 9:5.     Other Benefits
              Sec. 9:6.     Execution of Receipts and Releases
              Sec. 9:7.     No Guarantee of Interests
              Sec. 9:8.     Payment of Expenses
              Sec. 9:9.     Company Records
              Sec. 9:10.    Information
              Sec. 9:11.    No Liability of Company
              Sec. 9:12.    Company Action
              Sec. 9:13.    Severability
              Sec. 9:14.    Notices
              Sec. 9:15.    Waiver of Notice
              Sec. 9:16.    Successors
              Sec. 9:17.    Headings
              Sec. 9:18.    Governing Law
              Sec. 9:19.    Word Usage
              Sec. 9:20.    Remedies

Article X:    Approval of Shareholders


<PAGE>


                          1999 Stock Option Plan
                                    of

                           TGC Industries, Inc.

     This TGC Industries,  Inc. 1999 Stock Option Plan (the "Plan") provides for
the granting of:

          (a)  Incentive  Stock  Options  (hereinafter  defined)  to certain key
employees of TGC Industries,  Inc., a Texas corporation ("Company"),  and/or its
Affiliates (hereinafter defined), and

     (b)  Nonstatutory  Stock  Options  (hereinafter  defined)  to  certain  key
employees of Company, and/or its Affiliates,  and to certain individuals who are
not employees of Company or its Affiliates.

     The purpose of the Plan is to provide an  incentive  for key  employees  of
Company  and/or its  Affiliates,  and for  individuals  who are not employees of
Company  and/or its  Affiliates  but who from time to time  provide  substantial
advice or other  assistance  or services to Company  and/or its  Affiliates,  to
remain in the service of Company  and/or its  Affiliates  or continue to provide
such  assistance,  to extend to them the  opportunity  to acquire a  proprietary
interest in Company so that they will apply  their best  efforts for the benefit
of Company,  and to aid Company in attracting  able persons to enter the service
of Company and/or its Affiliates or provide such assistance.

                                   Article I
                                  Definitions

     Sec. 1:1.  Act.  "Act" shall mean the  Securities  Exchange Act of 1934, as
amended.

     Sec. 1:2. Affiliates.  "Affiliates" shall mean: (a) any corporation,  other
than Company,  in an unbroken chain of corporations  ending with Company if each
of the  corporations,  other than Company,  owns stock  possessing fifty percent
(50%) or more of the total combined  voting power of all classes of stock in one
of the other  corporations in such chain;  and (b) any  corporation,  other than
Company, in an unbroken chain of corporations  beginning with Company if each of
the  corporations,  other than the last corporation in the unbroken chain,  owns
stock  possessing fifty percent (50%) or more of the total combined voting power
of all classes of stock in one of the other corporations in such chain.

     Sec. 1:3.  Agreement.  "Agreement" shall mean the written agreement between
Company  and  a  Holder  evidencing  the  Option  granted  by  Company  and  the
understanding of the parties with respect thereto.

     Sec. 1:4. Board of Directors.  "Board of Directors" shall mean the board of
directors of Company.

     Sec.  1:5.  Code.  "Code" shall mean the Internal  Revenue Code of 1986, as
amended.

     Sec. 1:6.  Committee.  "Committee"  shall mean the committee  designated in
Article III hereof by the Board of Directors to administer this Plan.

     Sec. 1:7. Eligible Individuals.  "Eligible Individuals" shall mean: (a) key
employees, including officers and/or directors who are also employees of Company
and/or of any of its  Affiliates;  and (b)  individuals who are not employees of
Company and/or of its  Affiliates but who from time to time provide  substantial
advice or other assistance or services to Company and/or its Affiliates.

     Sec. 1:8.  Fair Market Value.  "Fair Market Value" shall mean, if the Stock
is traded  on one or more  established  markets  or  exchanges,  the mean of the
opening  and closing  prices of the Stock on the  primary  market or exchange on
which the Stock is  traded,  and if the Stock is not so traded or the Stock does
not trade on the relevant date, the value  determined in good faith by the Board
of Directors.  For purposes of valuing Incentive Stock Options,  the Fair Market
Value of stock shall be determined  without regard to any restriction other than
one which, by its terms, will never lapse.

     Sec. 1:9.  Holder.  "Holder"  shall mean an Eligible  Individual to whom an
Option has been granted.

     Sec. 1:10.  Incentive Stock Options.  "Incentive  Stock Options" shall mean
stock options that are intended to satisfy the  requirements  of Sec. 422 of the
Code.

     Sec. 1:11.  Nonstatutory Stock Options.  "Nonstatutory Stock Options" shall
mean stock  options  that are not  intended  to be, or are not  denominated  as,
Incentive Stock Options.

     Sec. 1:12. Options.  "Options" shall mean either Incentive Stock Options or
Nonstatutory Stock Options, or both.

     Sec. 1:13.  Stock.  "Stock" shall mean Company's  authorized $.30 par value
Common Stock.

                                   Article II

             Stock and Maximum Number of Shares Subject to the Plan

     Sec. 2:1.  Description  of Stock and Maximum  Shares  Allocated.  The Stock
which  Options  granted  hereunder  give a Holder the right to  purchase  may be
unissued or reacquired  shares of Stock,  as the Board of Directors  may, in its
sole and  absolute  discretion,  from  time to time  determine.  Subject  to the
adjustments  in Sec. 6.6 hereof,  the aggregate  number of shares of Stock to be
issued pursuant to the exercise of all Options granted  hereunder may equal, but
may not exceed, 300,000 shares of Company's Stock.

     Sec.  2:2.   Restoration  of  Shares.  If  an  Option  hereunder   expires,
terminates, or is not exercised for any reason during the term of this Plan, the
shares of Stock which were  subject to such Option  shall be  "restored"  to the
Plan by again being available for Options granted after the shares' restoration,
effective  as  of  the  first  day  of  the  year  following  such   expiration,
termination, or non-exercise.


                                 Article III
                          Administration of the Plan

     Sec.  3:1.  Stock Option  Committee.  This Plan will be  administered  by a
Committee  consisting  of four members to be  appointed  by  Company's  Board of
Directors.  The  members of the Stock  Option  Committee  must be members of the
Company's Board of Directors.

     Sec. 3:2. Duration,  Removal, Etc. The members of the Committee shall serve
at the pleasure of the Board of  Directors,  which shall have the power,  at any
time and from  time to time,  to remove  members  from the  Committee  or to add
members thereto. Vacancies on the Committee,  however caused, shall be filled by
the Board of Directors.

     Sec. 3:3. Meetings and Actions of Committee.  The Committee shall elect one
of its  members as its  Chairman  and shall hold its  meetings at such times and
places as it may determine.  All decisions and  determinations  of the Committee
shall be made by the majority  vote of all of its members  present at a meeting;
provided,  however,  that any decision or  determination  reduced to writing and
signed by all of the members of the Committee  shall be as fully effective as if
it had been made at a meeting duly called and held.  The  Committee may make any
rules and regulations for the conduct of its business that are not  inconsistent
with the provisions hereof and with the Bylaws of Company.

          Sec.  3:4.  Committee's  Powers.  Subject  to the  express  provisions
hereof,  the  Committee  shall  have the  authority,  in its  sole and  absolute
discretion to: (a) adopt,  amend,  and rescind  administrative  and interpretive
rules  and  regulations  relating  to the  Plan;  (b)  determine  the  terms and
provisions of the respective Agreements (which need not be identical), including
provisions  defining or otherwise  relating to: (i) subject to Article VI of the
Plan,  the term and the period or periods  and extent of  exercisability  of the
Options,  (ii) the extent to which the transferability of shares of Stock issued
upon  exercise  of Options is  restricted,  (iii) the effect of  termination  of
employment  upon the  exercisability  of the  Options,  and (iv) the  effect  of
approved leaves of absence  (consistent  with any applicable  regulations of the
Internal  Revenue  Service);  (c) accelerate the time of  exercisability  of any
Option that has been granted;  (d) construe the respective Option Agreements and
the Plan;  and (e) make all other  determinations  and  perform  all other  acts
necessary or advisable for administering  the Plan,  including the delegation of
such ministerial acts and  responsibilities  as the Committee deems appropriate.
The  Committee  may correct any defect or supply any omission or  reconcile  any
inconsistency in the Plan or in any Agreement in the manner and to the extent it
shall deem expedient to carry it into effect, and it shall be the sole and final
judge of such  expediency.  The  determination  of the  Committee on the matters
referred to in this Sec. 3.4 shall be final and conclusive.

                                 Article IV
                        Eligibility and Participation

     Sec. 4:1.  Eligible  Individuals.  Options may be granted hereunder only to
persons  who  are  Eligible  Individuals  at  the  time  of the  grant  thereof.
Notwithstanding any provision contained herein to the contrary, a person may not
receive an Incentive Stock Option  hereunder  unless he or she is an employee of
Company  and/or an  Affiliate,  nor shall a person be  eligible  to  receive  an
Incentive  Stock  Option  hereunder  if he or she,  at the time  such  Option is
granted,  would own (within the meaning of Secs.  422 and 424 of the Code) stock
possessing  more than ten percent  (10%) of the total  combined  voting power or
value of all  classes of stock of Company  or an  Affiliate,  unless at the time
such Incentive  Stock Option is granted the exercise price per share is at least
one hundred ten percent  (110%) of the Fair Market  Value of each share of stock
to which the Incentive  Stock Option  relates and the Incentive  Stock Option is
not  exercisable  after the  expiration  of five (5)  years  from the date it is
granted.

     Sec. 4:2. No Right to Option.  The adoption of the Plan shall not be deemed
to give any person a right to be granted an Option.


                                  Article V

              Grant of Options and Certain Terms of the Agreements

     Sec. 5:1.  Determination  of Eligible  Individuals.  Subject to the express
provisions  hereof,  the Committee shall  determine  which Eligible  Individuals
shall be granted  Options  hereunder  from time to time. In making  grants,  the
Committee shall take into  consideration  the  contribution the potential Holder
has made or may make to the success of Company and/or its Affiliates  along with
such  other  considerations  as the  Board of  Directors  may from  time to time
specify. The Committee shall also determine the number of shares subject to each
of such  Options  and shall  authorize  and cause  Company  to grant  Options in
accordance with such determinations.

     Sec.  5:2.  Date of Grant.  The date on which the  Committee  completes all
action  constituting  an offer of an  Option  to an  individual,  including  the
specification  of the  number of shares of Stock to be  subject  to the  Option,
shall be the date on which the Option  covered by an Agreement is granted,  even
though  certain  terms of the  Agreement  may not be determined at such time and
even though the Agreement may not be executed  until a later time.  For purposes
of the  preceding  sentence,  an offer shall be deemed made if the Committee has
completed  all  such  action  and has  communicated  the  grant  thereof  to the
potential  Holder.  In no event,  however,  may an  Optionee  gain any rights in
addition to those  specified by the  Committee in its grant,  regardless  of the
time that may pass  between the grant of the Option and the actual  execution of
the Agreement by Company and the Optionee.

     Sec. 5:3. Stock Option  Agreement.  Each Option granted  hereunder shall be
evidenced by an  Agreement,  executed by Company and the Eligible  Individual to
whom the Option is  granted,  incorporating  such terms as the  Committee  deems
necessary  or  desirable.  More than one Option may be granted  hereunder to the
same Eligible Individual and be outstanding concurrently hereunder. In the event
an Eligible  Individual is granted both one or more Incentive  Stock Options and
one or more  Nonstatutory  Stock  Options,  such grants  shall be  evidenced  by
separate  Agreements,  one for each of the Incentive Stock Option grants and one
for each of the Nonstatutory Stock Option grants.

     Sec. 5:4.  Forfeiture of Stock.  Each  Agreement may provide for conditions
giving  rise to the  forfeiture  of the  Stock  acquired  pursuant  to an Option
granted hereunder and/or such restrictions on the  transferability  of shares of
Stock acquired  pursuant to an Option granted  hereunder as the Committee in its
sole and absolute  discretion deems proper or advisable.  Such conditions giving
rise to forfeiture may include, but need not be limited to, the requirement that
the Holder render  substantial  services to Company  and/or its Affiliates for a
specified period of time. Such restrictions on transferability may include,  but
need not be limited to, options and rights of first refusal in favor of Company.

     Sec.  5:5. Cash Awards.  In addition,  the Board of Directors may authorize
the Committee to grant cash awards payable in connection with the exercise of an
Option  upon  such  terms  and  conditions  as are  specified  by the  Board  of
Directors;  provided  that no such  cash  award  shall be  effective  unless  it
complies with any applicable  requirements for exemption from liability pursuant
to Rule 16b-3 promulgated under the Act.


                                   Article VI
                        Terms and Conditions of Options

     All Options granted hereunder shall comply with, be deemed to include,  and
shall be subject to, the following terms and conditions:

     Sec. 6:1. Number of Shares. Each Agreement shall state the number of shares
of Stock to which it  relates.  Except  to the  extent  an  Agreement  otherwise
provides, the following limitations shall apply to the exercise of each Option:

     A. First Year.  A Holder may not  exercise any portion of his or her Option
during the first  twelve (12) month period  following  the date of grant of such
Option.

     B.  After  First  Year.  A Holder  may  exercise  up to (but not more than)
one-third of the total shares of Stock  subject to his or her Option at any time
after the first  twelve  (12) month  period  following  the day of grant of such
Option.

     C.  After  Second  Year.  A Holder may  exercise  up to (but not more than)
two-thirds of the total shares of Stock subject to his or her Option at any time
after the first  twenty-four  (24) month period  following  the date of grant of
such Option.

     D.  After  Third  Year.  A Holder may  exercise  all of the shares of Stock
subject to his or her Option at any time after the first  thirty-six  (36) month
period following the date of grant of such Option.

     E. Senior Status. Notwithstanding the limitations stated above, if a Holder
is  sixty-five  (65)  years of age or older  at the  time his or her  Option  is
granted,  such  Holder may  exercise  up to (but not more than)  one-half of the
total shares of Stock subject to such Option at any time during the first twelve
(12) month period  following the date of grant of such Option and thereafter may
exercise all of the shares of Stock subject to such Option.

     F. De Minimus  Limitation.  Subject to the limitations  stated above,  each
Option may be exercised at one time or on several successive occasions; however,
each Option may not be exercised in an amount less than one hundred (100) shares
at any one time (unless such exercise is being made as to the entire  portion of
Stock which may be purchased pursuant to this Plan).

     Sec. 6:2. Exercise Price. Each Agreement shall state the exercise price per
share of Stock.  The exercise  price per share of stock  subject to an Incentive
Stock  Option shall not be less than the greater of: (a) the par value per share
of the Stock;  or (b) one hundred  percent  (100%) of the Fair Market  Value per
share of  Company's  Stock on the date of the grant of the Option.  The exercise
price per share of stock  subject to a  Nonstatutory  Stock  Option shall not be
less than fifty percent (50%) of the Fair Market Value per share of the Stock on
the date of the grant of the Option.

     Sec. 6:3. Medium and Time of Payment,  Method of Exercise,  and Withholding
Taxes.

     A. Exercise of Option.  Except as otherwise  permitted  below, the exercise
price of stock  covered by an Option  shall be payable  upon the exercise of the
Option in cash, by certified or cashier's check. Exercise of an Option shall not
be effective until Company has received written notice of exercise.  Such notice
must specify the number of whole shares to be purchased  and be  accompanied  by
payment  in full  of the  aggregate  exercise  price  of the  number  of  shares
purchased.  Company shall not in any case be required to sell, issue, or deliver
a fractional share with respect to any Option.

     1. Stock-for-Stock  Exercise. With the consent of the Committee, the Holder
may pay the exercise  price with shares of Stock of Company which have been held
by the Holder for at least six (6) months prior to the date of exercise, or with
the consent of the  Committee,  by a combination  of cash and such shares.  Such
Stock shall be duly endorsed for transfer to Company. Such Stock shall be deemed
to have a fair  market  value on the  date of  delivery  equal to the  aggregate
purchase  price of the  shares  with  respect  to which  such  Option or portion
thereof is being exercised.

     2.  Cashless  Exercise/Sale  Method.  With the  consent  of the  Committee,
payment in full of the  exercise  price of the Option  may be made  through  the
Company's receipt of a copy of instructions to a broker directing such broker to
sell the Stock for which the Option is being exercised,  to remit to the Company
an amount equal to the aggregate exercise price of such Option, with the balance
being remitted to Holder.

     3. Cashless Exercise/Net Method. With the consent of the Committee, payment
in full of the  exercise  price  of the  Option  may be made,  based on  written
instructions  received from the Holder,  by Company's  issuance to the Holder of
that  number of shares of Stock  having a fair  market  value  equal to only the
"profit  portion" of his, her, or its Option (i.e.,  the excess of the then fair
market value of the Stock over the Holder's exercise price).

     B. New Options.  In the event that a Holder pays the exercise  price of his
Option, in whole or in part, with previously owned shares of Stock,  pursuant to
the rules specified above, then, if and to the extent approved by the Committee,
in addition to the shares of Stock  purchased  pursuant to the Option  exercise,
such Holder shall also receive a new Option, subject to the terms and conditions
set forth below and in the  Holder's  individual  Stock Option  Agreement.  Upon
exercise of the Option with  payment in the form of either  shares of Stock or a
combination  of cash and shares of Stock,  the  Committee  may,  in its sole and
absolute discretion,  grant the Holder a new Option for shares of Stock equal to
the number of shares  that were  delivered  by the Holder to Company to pay,  in
whole or in part, the exercise price of the previous Option.  The exercise price
of the new Option  shall be equal to at least 100% of the Fair Market  Value per
share of the Stock on the date of the exercise of the previous Option. Provided,
however,  the new Option  cannot be  exercised by the Holder until the later of:
(1) the  exercisability  dates specified in the individual Option Agreement;  or
(2) six (6)  months  after the date of  grant.  As a  further  condition  on the
exercisability  of the new  Option,  the shares of Stock  received by the Holder
upon  exercise of his or her  previous  Option must be held by the Holder for at
least six (6) months prior to any sale of such shares by the Holder. Any sale of
such shares by a Holder  prior to the  expiration  of the six (6) month  holding
period shall render the new Option  non-exercisable.  Nothing in this  paragraph
shall  prevent the Committee  from  granting a Holder  another new Option in the
future when the  previous new Option is exercised by the Holder with the payment
of previously owned shares of Stock.

          C.     Withholding.

     1. General.  The Committee may, in its discretion,  require a Holder to pay
to Company at the time of exercise of an Option (or portion  thereof) the amount
that Company  deems  necessary to satisfy its  obligation  to withhold  Federal,
state,  or local income or other taxes incurred by reason of the exercise.  Upon
the exercise of an Option requiring tax withholding, a Holder may make a written
request to have shares of stock withheld by Company from the shares otherwise to
be  received.  The number of shares so  withheld  shall have an  aggregate  Fair
Market  Value on the date of  exercise  sufficient  to  satisfy  the  applicable
withholding  taxes.  The  acceptance of any such request by a Holder shall be at
the sole  discretion of the  Committee,  including,  if deemed  necessary by the
Committee,   approval  by  the  Securities  and  Exchange   Commission  and  the
satisfaction of any additional requirements necessary to obtain such approval.

               2. Additional Sec. 16b Requirements.  Currently,  with respect to
Option  holders  subject  to  liability  under  Section  16b  of the  Act,  such
additional  requirements include the following:  (1) any previously owned shares
of Stock used to satisfy the  withholding  obligation must have been held by the
taxpayer for at least six (6) months,  and any Option shares otherwise  issuable
hereunder to be withheld to satisfy such  obligations may be so withheld only if
both the  exercise of the Option and the  election to have shares  withheld  are
made at least six (6) months  after the date of grant;  (2) the Option  holder's
election  must be made:  (a) at least six (6)  months  less one day prior to the
date on which  the  option  exercise  becomes  taxable,  or (b)  within a 10-day
"window  period"  beginning on the third  business day  following the release of
Company's  annual or quarterly  financial  reports and ending on the twelfth day
thereafter  (but in no event  later  than the date the option  exercise  becomes
taxable);  (3) Company has been subject to the Act's reporting  requirements for
more than a year and has filed all reports and  statements  required to be filed
pursuant to Section 13 of the Act;  (4) Company  regularly  issues  quarterly or
annual  summary  statements  of  sales  and  earnings;  (5) all  members  of the
Committee  administering  the Plan with  respect  to Option  holders  subject to
liability  under Section 16b of the Act are  "disinterested"  in accordance with
Rule 16b-3  promulgated  under the Act; (6) the  Committee  will be empowered to
consent to or disapprove an Option holder's  withholding  election;  and (7) any
withholding election will be required to be irrevocable.

     Sec. 6:4.     Terms, Time of Exercise, and Transferability of Options.

     A.  Decrease  in Term of  Option.  In  addition  to such  other  terms  and
conditions as may be included in a particular  Agreement  granting an Option, an
Option shall be exercisable  during a Holder's lifetime only by him or her or by
his  or  her  guardian  or  legal   representative.   An  Option  shall  not  be
transferrable  other than by will or the laws of descent and distribution.  Each
Option shall also be subject to the following  terms and  conditions  (except to
the extent a Holder's Agreement otherwise provides):

          1.  Termination of Employment or Directorship.

              a. Voluntary Termination.  If a Holder ceases to be employed by at
least one of the  employers in the group of employers  consisting of Company and
its Affiliates because the Holder  voluntarily  terminates his or her employment
with such group of employers and the Holder does not remain or thereupon  become
a director of Company or one or more of its Affiliates, or if a Holder ceases to
be a director of at least one of the  corporations  in the group of corporations
consisting  of Company  and its  Affiliates  and the  Holder  does not remain or
thereupon  become an employee of Company or one or more of its  Affiliates,  the
portion (if any) of an Option that remains  unexercised,  including that portion
(if any) that pursuant to the Agreement is not yet  exercisable,  as of the date
of the Holder's termination of employment or ceasing to be a director, whichever
occurs later,  shall  terminate and cease to be  exercisable as of such date (or
ninety  [90] days prior  thereto if the Holder  elected to  exercise  his or her
Option  in  anticipation  of such  termination  [to be  determined  in the  sole
discretion of the Committee]).

              b.  Termination for Cause. If a Holder ceases to be employed by at
least one of the  employers in the group of employers  consisting of Company and
its Affiliate  because any of such entities  terminates the Holder's  employment
for cause, the portion (if any) of an Option that remains unexercised, including
that portion (if any) that pursuant to the Agreement is not yet exercisable,  at
the time of the Holder's termination of employment, shall terminate and cease to
be  exercisable  immediately  upon such  termination  (or ninety [90] days prior
thereto if the Holder elected to exercise his or her Option in  anticipation  of
such termination [to be determined in the sole discretion of the Committee]).  A
Holder's  employment shall be deemed terminated "for cause" if terminated by the
Board of  Directors  of  Company  (or the board of  directors  of an  Affiliate)
because of incompetence, insubordination,  dishonesty, other acts detrimental to
the interest of Company  and/or its  Affiliates,  or any material  breach by the
Holder of any employment, nondisclosure,  noncompetition, or other contract with
Company and/or one of its Affiliates. Whether "cause" exists shall be determined
by such  Board  of  Directors  in its sole  discretion  and in good  faith.  The
exercise of an option in  anticipation  of a termination for cause shall be null
and void.

     c. Termination Without Cause. If a Holder ceases to be employed by at least
one of the  employers  in the group of employers  consisting  of Company and its
Affiliates because one or more of such entities terminates the employment of the
Holder  for  otherwise  than for  "cause,"  and the  Holder  does not  remain or
thereupon become a director of Company and/or one or more of its Affiliates, the
Holder shall have the right for thirty (30) days following  such  termination to
exercise  the  Option  with  respect  to that  portion  thereof  that has become
exercisable  pursuant to Holder's  Agreement as of the date of such termination,
and thereafter the Option shall terminate and cease to be exercisable.

     2.  Disability.  If a Holder  ceases to be  employed by at least one of the
employers in the group of employers  consisting of Company and its Affiliates by
reason of  disability  (as  defined in Sec.  22(e)(3)  of the Code) and does not
remain  or  thereupon  become  a  director  of  Company  or one or  more  of its
Affiliates,  or if the  Holder  ceases  by  reason  of such  disability  to be a
director  of at least  one of the  corporations  in the  group  of  corporations
consisting  of Company and its  Affiliates,  the Holder shall have the right for
ninety (90) days after the date of termination of employment  with, or cessation
of directorship  of, such group of employers by reason of disability,  whichever
occurs later,  to exercise an Option to the extent such Option is exercisable on
the date of his or her  termination  of  employment,  and  thereafter the Option
shall terminate and cease to be exercisable.

     3. Death.  If a Holder dies while in the employ of Company or an Affiliate,
or dies while a director of Company or an Affiliate,  his or her Option shall be
exercisable by his or her legal  representatives,  legatees, or distributees for
six (6) months  following  the date of the  Holder's  death to the  extent  such
Option is exercisable  on the Holder's date of death,  and thereafter the Option
shall terminate and cease to be exercisable.

     B. Term of  Option.  Notwithstanding  any  other  provision  of this  Plan,
including the provisions of Subsection A above, no Incentive Stock Option may be
exercised  after the  expiration  of ten (10) years from the date it was granted
(or the  period  specified  in Sec.  4.1,  if  applicable).  The  Committee  may
prescribe in any Agreement that the Option evidenced thereby may be exercised in
full or in part as to any number of shares  subject  thereto at any time or from
time to time  during the term of the  Option,  or in such  installments  at such
times during said term as the Committee may prescribe.  Except as provided above
and unless  otherwise  provided in any Agreement,  an Option may be exercised at
any time or from time to time during the term of the Option.  Such  exercise may
be as to  any or  all  whole  (but  no  fractional)  shares  which  have  become
purchasable under the Option.

     C. Issuance of Stock  Certificates.  Within a reasonable time, or such time
as may be permitted  by law,  after  Company  receives  written  notice that the
Holder has elected to exercise all or a portion of an Option,  such notice to be
accompanied by payment in full of the aggregate  exercise price of the number of
shares purchased, Company shall issue and deliver a certificate representing the
shares  acquired as a result of the  exercise and any other  amounts  payable in
consequence  of such  exercise.  In the event  that a Holder  exercises  both an
Incentive Stock Option, or portion thereof,  and a Nonstatutory Stock Option, or
a portion  thereof,  separate Stock  certificates  shall be issued,  one for the
Stock subject to the Incentive Stock Option and one for the Stock subject to the
Nonstatutory Stock Option. The number of shares of Stock transferrable due to an
exercise of an Option under this Plan shall not be increased  due to the passage
of time, except as may be provided in an Agreement.

     D. Issuance in Compliance  With Securities  Laws.  Nothing herein or in any
Option granted hereunder shall require Company to issue any shares upon exercise
of any Option if such  issuance  would,  in the opinion of counsel for  Company,
constitute a violation of the Securities Act of 1933, as amended, or any similar
or  superseding  statute  or  statutes,  or  any  other  applicable  statute  or
regulation, as then in effect.

     E. Investment Legend. At the time of exercise of an Option, Company may, as
a condition precedent to the exercise of such Option, require from the Holder of
the  Option  (or  in  the  event  of  his  or  her  death,   his  or  her  legal
representatives,  legatees,  or distributees) such written  representations,  if
any,  concerning  his  or  her  intentions  with  regard  to  the  retention  or
disposition  of the shares  being  acquired  by exercise of such Option and such
written  covenants and agreements,  if any, as to the manner of disposal of such
shares as, in the opinion of counsel to Company, may be necessary to ensure that
any disposition by such Holder (or in the event of his or her death,  his or her
legal representatives,  legatees, or distributees), will not involve a violation
of the Securities Act of 1933, as amended, or any similar or superseding statute
or statutes, or any other applicable state or federal statute or regulation,  as
then in effect.  Certificates  for shares of Stock,  when  issued,  may have the
following  legend,  or statements  of other  applicable  restrictions,  endorsed
thereon, and may not be immediately transferable:

          The shares of Stock evidenced by this  certificate have been issued to
          the  registered  owner in reliance upon written  representations  that
          these shares have been purchased for investment.  These shares may not
          be sold,  transferred,  or assigned unless,  in the opinion of Company
          and its legal counsel,  such sale, transfer, or assignment will not be
          in violation of the  Securities  Act of 1933,  as amended,  applicable
          rules and regulations of the Securities and Exchange  Commission,  and
          any applicable state securities laws.

     Sec.  6:5.  Limitation  on Aggregate  Value of Shares That May Become First
Exercisable  During Any Calendar  Year Under an  Incentive  Stock  Option.  With
respect to any  Incentive  Stock Option  granted  under this Plan, to the extent
that the aggregate  Fair Market Value of shares of Stock exceed  $100,000,  then
such excess over  $100,000  shall not be  considered  as subject to an Incentive
Stock Option,  but rather shall be considered as subject to a Nonstatutory Stock
Option.  This rule  shall be  applied  by  taking  shares  of Stock  subject  to
Incentive  Stock Options that are purchasable for the first time in the calendar
year into  account  in the order in which  such  Incentive  Stock  Options  were
granted.

     Sec. 6:6.     Adjustments Upon Changes in Capitalization, Merger, Etc.

     A.  Method  of  Adjustment.  In the event of any  change  in the  number of
outstanding  shares of Stock effected without receipt of consideration  therefor
by Company (other than as a result of the conversion of Company's Class B Common
Stock  into  Class A Common  Stock)  by reason  of a stock  dividend,  or split,
combination, exchange of shares or other recapitalization, merger, or otherwise,
in which Company is the surviving corporation, the aggregate number and class of
the reserved shares,  the number and class of shares subject to each outstanding
Option, and the exercise price of each outstanding Option shall be automatically
adjusted to accurately  and equitably  reflect the effect thereon of such change
(provided  that any  fractional  share  resulting  from such  adjustment  may be
eliminated).  In the event of a dispute concerning such adjustment, the decision
of the  Committee  shall be  conclusive.  The number of  reserved  shares or the
number  of shares  subject  to any  outstanding  Option  shall be  automatically
reduced by any fraction  included therein which results from any adjustment made
pursuant hereto.

     B.  Termination of Option.  The following  provisions  shall apply unless a
Holder's Agreement provides otherwise.  A dissolution or liquidation of Company;
a sale  of all  or  substantially  all of the  assets  of  Company  where  it is
contemplated  that within a reasonable  period of time  thereafter  Company will
either  be  liquidated  or  converted   into  a   nonoperating   company  or  an
extraordinary  dividend will be declared  resulting in a partial  liquidation of
Company  (but in all  cases  only with  respect  to those  employees  whom it is
anticipated  will lose their  employment  with Company and its  Affiliates  as a
result of such sale of assets);  a merger or consolidation  (other than a merger
effecting a reincorporation of Company in another state or any other merger or a
consolidation in which the  shareholders of the surviving  corporation and their
proportionate  interests  therein  immediately after the merger or consolidation
are   substantially   identical  to  the   shareholders  of  Company  and  their
proportionate   interests   therein   immediately   prior  to  the   merger   or
consolidation)  in which Company is not the surviving  corporation  (or survives
only as a  subsidiary  of  another  corporation  in a  transaction  in which the
shareholders of the parent of Company and their proportionate  interests therein
immediately  after  the  transaction  are  not  substantially  identical  to the
shareholders of Company and their  proportionate  interests therein  immediately
prior  to  the  transaction)  shall  cause  every  Option  then  outstanding  to
terminate,  but the Holders of each such then  outstanding  Option shall, in any
event, have the right, immediately prior to such dissolution,  liquidation, sale
of assets, merger, consolidation,  or transaction, to exercise each such Option,
to the extent not theretofore exercised,  without regard to the determination as
to the periods and  installments of  exercisability  made pursuant to a Holder's
Agreement  if (and only if) such  Options  have not at that time expired or been
terminated.

     Sec.  6:7.  Rights  as a  Shareholder.  A Holder  shall  have no right as a
shareholder  with  respect  to any shares  covered by his or her Option  until a
certificate  representing  such  shares is issued to him or her.  No  adjustment
shall be made for dividends (ordinary or extraordinary, whether in cash or other
property) or distributions or other rights for which the record date is prior to
the date such certificate is issued (except as provided in Sec. 6.6. hereof).

     Sec. 6:8. Modification,  Extension,  and Renewal of Options. Subject to the
terms and  conditions of and within the  limitations  of the Plan, the Committee
may modify,  extend,  or renew  outstanding  Options  granted under the Plan, or
accept  the  surrender  of  Options  outstanding  hereunder  (to the  extent not
theretofore  exercised)  and authorize the granting of new Options  hereunder in
substitution therefor (to the extent not theretofore  exercised).  The Committee
may not,  however,  without the consent of the  Holder,  modify any  outstanding
Incentive  Stock Options so as to specify a lower  exercise  price or accept the
surrender of outstanding  Incentive  Stock Options and authorize the granting of
new  Options in  substitution  therefor  specifying  a lower  option  price.  In
addition,  no  modification  of an Option  granted  hereunder  may,  without the
consent  of the  Holder,  alter or impair any  rights or  obligations  under any
Option  theretofore  granted  hereunder to such Holder under the Plan, except as
may be  necessary  with  respect to  Incentive  Stock  Options  to  satisfy  the
requirements of Sec. 422 of the Code.

     Sec.  6:9.  Furnish  Information.  Each Holder shall furnish to Company all
information  requested  by Company to enable it to comply with any  reporting or
other  requirements  imposed upon Company by or under any applicable  statute or
regulation.

     Sec. 6:10. Obligation to Exercise;  Termination of Employment. The granting
of an Option  hereunder  shall impose no obligation  upon the Holder to exercise
the  same or any  part  thereof.  In the  event  of a  Holder's  termination  of
employment with Company or an Affiliate,  the  unexercised  portion of an Option
granted hereunder shall terminate in accordance with Sec. 6.4 hereof.

     Sec. 6:11. Agreement  Provisions.  The Agreements authorized under the Plan
shall  contain  such  provisions  in  addition  to  those  required  by the Plan
(including, without limitation, restrictions or the removal of restrictions upon
the  exercise of the Option and the  retention  or  transfer  of shares  thereby
acquired) as the Committee  deems  advisable.  Each Agreement shall identify the
Option  evidenced  thereby as an Incentive  Stock Option or  Nonstatutory  Stock
Option, as the case may be, and no Agreement shall cover both an Incentive Stock
Option and Nonstatutory Stock Option. Except as provided by Subsection B of Sec.
6.6, each  Agreement  relating to an Incentive  Stock Option  granted  hereunder
shall  contain  such  limitations  and  restrictions  upon the  exercise  of the
Incentive  Stock  Option to which it relates as is necessary  for the  Incentive
Stock Option to which such  Agreement  relates to constitute an incentive  stock
option, as defined in Sec. 422 of the Code.


                                 Article VII
                               Duration of Plan

     No Incentive Stock Options may be granted  hereunder after the date that is
ten (10)  years  from the  earlier  of: (i) the date this Plan is adopted by the
Board  of  Directors;  or (ii) the  date  this  Plan is  approved  by  Company's
shareholders. In addition, with respect to shares of Stock not currently covered
by an outstanding  Option,  this Plan may be terminated at any time by the Board
of Directors.


                                 Article VIII
                              Amendment of Plan

     The Board of Directors  may,  insofar as permitted by law,  with respect to
any shares at the time are not subject to Options,  suspend or  discontinue  the
Plan or revise or amend it in any respect whatsoever;  provided,  however, that,
without the approval of the holders of a majority of the  outstanding  shares of
voting stock of all classes of Company, no such revision or amendment shall: (a)
change  the number of shares of the Stock  subject  to the Plan,  (b) change the
designation of the class of employees eligible to receive Options,  (c) decrease
the price at which  Incentive  Stock  Options  may be  granted,  (d)  remove the
administration of the Plan from the Committee, or (e) without the consent of the
affected  Holder,  cause the  Incentive  Stock  Options  granted  hereunder  and
outstanding at such time that satisfied the requirements of Sec. 422 of the Code
to no longer satisfy such requirements.

                               Article IX
                                 General

     Sec. 9:1.  Application of Funds. The proceeds  received by Company from the
sale of shares pursuant to Options shall be used for general corporate purposes.

     Sec. 9:2. Right of Company and Affiliates to Terminate Employment.  Nothing
contained  in the Plan,  or in any  Agreement,  shall confer upon any Holder the
right to continue in the employ of Company or any Affiliate, or interfere in any
way  with the  rights  of  Company  or any  Affiliate  to  terminate  his or her
employment at any time.

     Sec. 9:3. No Liability for Good Faith  Determinations.  Neither the members
of the Board of Directors  nor any member of the  Committee  shall be liable for
any act, omission,  or determination taken or made in good faith with respect to
the Plan or any Option  granted  under it, and members of the Board of Directors
and the Committee  shall be entitled to  indemnification  and  reimbursement  by
Company in respect of any claim, loss, damage, or expense (including  attorneys'
fees,  the costs of settling any suit,  provided such  settlement is approved by
independent legal counsel selected by Company,  and amounts paid in satisfaction
of a  judgment,  except a  judgment  based on a finding  of bad  faith)  arising
therefrom  to the full  extent  permitted  by law and  under any  directors  and
officers  liability or similar insurance  coverage that may from time to time be
in effect.

     Sec.  9:4.  Information  Confidential.  As  partial  consideration  for the
granting of each Option  hereunder,  the Holder shall agree with Company that he
or she will keep  confidential  all information and knowledge that he or she has
relating to the manner and amount of his  participation  in the Plan;  provided,
however,  that such  information  may be disclosed as required by law and may be
given in confidence to the Holder's spouse, tax, and financial advisors, or to a
financial institution to the extent that such information is necessary to secure
a loan.  In the event any breach of this promise  comes to the  attention of the
Committee,  it shall take into consideration such breach, in determining whether
to  recommend  the  grant  of any  future  Option  to such  Holder,  as a factor
militating  against the  advisability of granting any such future Option to such
individual.

     Sec. 9:5. Other Benefits.  Participation in the Plan shall not preclude the
Holder  from  eligibility  in any other  stock  option  plan of  Company  or any
Affiliate or any old age benefit, insurance, pension, profit sharing retirement,
bonus,  or other extra  compensation  plans which  Company or any  Affiliate has
adopted, or may, at any time, adopt for the benefit of its employees.

     Sec. 9:6.  Execution of Receipts and  Releases.  Any payment of cash or any
issuance or  transfer  of shares of Stock to the Holder,  or to his or her legal
representative, heir, legatee, or distributee, in accordance with the provisions
hereof,  shall, to the extent thereof,  be in full satisfaction of all claims of
such  persons   hereunder.   The  Committee   may  require  any  Holder,   legal
representative,  heir, legatee, or distributee, as a condition precedent to such
payment,  issuance,  or transfer,  to execute a release and receipt  therefor in
such form as it shall determine.

     Sec.  9:7. No Guarantee of  Interests.  Neither the  Committee  nor Company
guarantees the Stock of Company from loss or depreciation.

     Sec. 9:8. Payment of Expenses. All expenses incident to the administration,
termination, or protection of the Plan, including, but not limited to, legal and
accounting fees, shall be paid by Company or its Affiliates.

     Sec. 9:9. Company Records.  Records of Company or its Affiliates  regarding
the Holder's  period of  employment,  termination  of employment  and the reason
therefor,  leaves  of  absence,  re-employment,   and  other  matters  shall  be
conclusive for all purposes hereunder,  unless determined by the Committee to be
incorrect.

     Sec. 9:10.  Information.  Company and its Affiliates shall, upon request or
as may be specifically required hereunder, furnish or cause to be furnished, all
of the  information  or  documentation  which is  necessary  or  required by the
Committee to perform its duties and functions under the Plan.

     Sec.  9:11.  No  Liability of Company.  Company  assumes no  obligation  or
responsibility  to the  Holder or his or her  personal  representatives,  heirs,
legatees,  or distributees for any act of, or failure to act on the part of, the
Committee.

     Sec.  9:12.  Company  Action.  Any action  required of Company  shall be by
resolution  of its  Board  of  Directors  or by a  person  authorized  to act by
resolution of the Board of Directors.

     Sec.  9:13.  Severability.  If any  provision  of  this  Plan is held to be
illegal or invalid for any reason, the illegality or invalidity shall not affect
the remaining  provisions  hereof,  but such provision shall be fully severable,
and the Plan  shall be  construed  and  enforced  as if the  illegal  or invalid
provision had never been included herein.

     Sec. 9:14. Notices. Whenever any notice is required or permitted hereunder,
such notice must be in writing and  personally  delivered  or sent by mail.  Any
notice  required or permitted to be  delivered  hereunder  shall be deemed to be
delivered on the date on which it is personally delivered,  or, whether actually
received or not, on the third  business  day after it is deposited in the United
States mail, certified or registered,  postage prepaid,  addressed to the person
who is to receive it at the address which such person has theretofore  specified
by written  notice  delivered in  accordance  herewith.  Company or a Holder may
change,  at any time and from time to time, by written notice to the other,  the
address which it or he had theretofore  specified for receiving  notices.  Until
changed in accordance herewith, Company and each Holder shall specify as its and
his or her address for receiving  notices the address set forth in the Agreement
pertaining to the shares to which such notice relates.

     Sec. 9:15.  Waiver of Notice.  Any person entitled to notice  hereunder may
waive such notice.

     Sec. 9:16.  Successors.  The Plan shall be binding upon the Holder,  his or
her heirs, legatees,  and legal  representatives,  upon Company, its successors,
and assigns, and upon the Committee, and its successors.

     Sec. 9:17.  Headings.  The titles and headings of Sections and  Subsections
are included for  convenience  of reference only and are not to be considered in
construction of the provisions hereof.

     Sec.  9:18.  Governing  Law.  All  questions  arising  with  respect to the
provisions  of the Plan shall be determined  by  application  of the laws of the
State of Texas  except to the extent  Texas law is  preempted  by  federal  law.
Questions  arising  with  respect to the  provisions  of an  Agreement  that are
matters of contract law shall be governed by the laws of the state  specified in
the  Agreement,  except to the extent Texas  corporate  law  conflicts  with the
contract law of such state, in which event Texas corporate law shall govern. The
obligation  of  Company  to sell and  deliver  Stock  hereunder  is  subject  to
applicable laws and to the approval of any  governmental  authority  required in
connection with the authorization, issuance, sale, or delivery of such Stock.

     Sec.  9:19.  Word  Usage.  Words used in the  masculine  shall apply to the
feminine where applicable,  and wherever the context of this Plan dictates,  the
plural shall be read as the singular and the singular as the plural.

     Sec.  9:20.  Remedies.   Company  may  recover  from  a  Holder  reasonable
attorneys'  fees incurred in connection  with the  enforcement  of the terms and
provisions  of the  Plan and any  Agreement  whether  by an  action  to  enforce
specific performance or for damages for its breach or otherwise.


                                  Article X
                           Approval of Shareholders

     The Plan  shall  take  effect  on the date it is  adopted  by the  Board of
Directors. However, if this Plan is not approved by the holders of a majority of
the  outstanding  shares of  Company's  Common  Stock and  Preferred  Stock at a
Meeting  of  Shareholders  scheduled  to be held in 2000,  any  Options  granted
hereunder  shall be null,  void,  and of no force and  effect as of their  grant
date.

     IN  WITNESS  WHEREOF,  TGC  Industries,  Inc.,  acting by and  through  its
officers  hereunto duly  authorized has executed this instrument to be effective
the 14 day of December, 1999.

                              TGC INDUSTRIES, INC.

                              By:   /s/ Allen T. McInnes

                                    -----------------------------------
                                    Allen T. McInnes,
                                    Chairman of the Board


4891.00001/160561.1

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<NAME>                   TGC Industries, Inc.
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