VISTA INFORMATION SOLUTIONS INC
8-K, 1999-01-29
BUSINESS SERVICES, NEC
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                                  UNITED STATES

                       SECURITIES AND EXCHANGE COMMISSION

                             Washington, D.C. 20549

                                    FORM 8-K

                                 CURRENT REPORT

     Pursuant To Section 13 Or 15(d) Of The Securities Exchange Act Of 1934

Date of Report (Date of earliest event reported)  January 14, 1999

                        VISTA Information Solutions, Inc.
               --------------------------------------------------
               (Exact name of registrant as specified in charter)

       Delaware                       0-20312                 41-1293754
       --------                       -------                 ----------
(State or other jurisdiction  (Commission File Number)    (IRS Employer 
of incorporation)                                         Identification No.)

5060 Shoreham Place, #300, San Diego, CA                     92122
- -----------------------------------------------------------------------
(Address of principal executive offices)                     (Zip Code)

Registrant's telephone number, including area code  (619) 450-6100
                                                    --------------
                                 Not applicable
                                 --------------
          (Former name or former address, if changed since last report)


<PAGE>

ITEM 2.  Acquisition Or Disposition Of Assets

     On January 14, 1999, VISTA Information Solutions, Inc., a Delaware 
corporation ("VISTA"), through its subsidiaries, acquired all of the 
outstanding partnership interests of GeoSure, L.P. ("GeoSure") pursuant to 
the terms of a Partnership Interest Purchase Agreement (the "Agreement"). In 
exchange for the partnership interests of GeoSure, VISTA (through its 
subsidiaries) issued an aggregate of 2,589,998 shares of common stock, par 
value $0.001 per share, of VISTA ("VISTA Common Stock"), with 259,000 of such 
shares being deposited into an escrow in accordance with the terms of the 
Agreement.

     The number of shares of VISTA Common Stock issued in exchange for the 
partnership interests of GeoSure was based on an arm's length negotiation 
between the parties after considering the perceived value of GeoSure, the 
liabilities of GeoSure, and the market value of shares of VISTA Common Stock. 
Prior to this transaction, none of the partners of GeoSure had any material 
relationship with VISTA or its directors or officers.

     VISTA intends to continue operating the business of GeoSure and its 
subsidiaries in providing environmental risk information, flood certification 
and flood insurance, although reductions of personnel resources and 
dispositions of excess assets will likely take place over time.


ITEM 7.  Financial Statements And Exhibits

         (a)      Financial statements of business acquired. To be filed by 
                  amendment within 60 days of this report.

         (b)      Pro forma financial information.  To be filed by amendment 
                  within 60 days of this report.

         (c)      Exhibits.

EXHIBIT                DESCRIPTION
- -------                -----------

Exhibit 2              Partnership Interest Purchase Agreement made and entered
                       into as of January 5, 1999 by and among VISTA
                       INFORMATION SOLUTIONS, INC., VISTA Environmental
                       Information, Inc., GEOSURE, L.P. and the partners of
                       GEOSURE. Schedules, exhibits and similar attachments to
                       this Exhibit have not been filed; upon request, VISTA
                       will furnish supplementally to the Commission a copy of
                       any omitted schedule.

                                       -2-

<PAGE>

                                   SIGNATURES

     Pursuant to the requirements of the Securities Exchange Act of 1934, the 
registrant has duly caused this report to be signed on its behalf by the 
undersigned hereunto duly authorized.

                                             VISTA INFORMATION SOLUTIONS, INC.

Date:    January 29, 1999           By:      /s/ BRIAN CONN
                                             ---------------------------------
                                             Brian Conn
                                             Principal Accounting Officer










                                       -3-

<PAGE>


                                INDEX OF EXHIBITS



EXHIBIT                 DESCRIPTION
- -------                 -----------

Exhibit 2               Partnership Interest Purchase Agreement made and entered
                        into as of January 5, 1999 by and among VISTA
                        Information Solutions, Inc., VISTA Environmental
                        Information, Inc., GeoSure, L.P. and the partners of
                        GeoSure. Schedules, exhibits and similar attachments to
                        this Exhibit have not been filed; upon request, VISTA
                        will furnish supplementally to the Commission a copy of
                        any omitted schedule.





                                       -4-



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                      PARTNERSHIP INTEREST PURCHASE AGREEMENT

                                   by and between
                                          
                         VISTA INFORMATION SOLUTIONS, INC.
                              a Delaware corporation,
                                          
                       VISTA ENVIRONMENTAL INFORMATION, INC.
                              a Delaware corporation,
                                          
                                   GEOSURE, L.P.,
                           a New York limited partnership
                                          
                                        and
                                          
                           THE PARTNERS OF GEOSURE, L.P.
                                          
                            Dated as of January 5, 1999
                                          


<PAGE>


1.   THE ACQUISITION . . . . . . . . . . . . . . . . . . . . . . . . .       1
     1.1    Sale and Purchase of Partnership Interest  . . . . . . . .       1
     1.2    Closing. . . . . . . . . . . . . . . . . . . . . . . . . .       1
     1.3    Effect of the Acqusition . . . . . . . . . . . . . . . . .       2
     1.4    Effect on Limited Partnership Interest . . . . . . . . . .       2
     1.5    Accounting Treatment . . . . . . . . . . . . . . . . . . .       2

2.   REPRESENTATIONS AND WARRANTIES GAMMA. . . . . . . . . . . . . . .       2
     2.1    Organization, Standing and Power . . . . . . . . . . . . .       3
     2.2    Partnership Documents. . . . . . . . . . . . . . . . . . .       3
     2.3    Capitalization, etc. . . . . . . . . . . . . . . . . . . .       3
     2.4    Financial Statements . . . . . . . . . . . . . . . . . . .       4
     2.5    Absence of Changes . . . . . . . . . . . . . . . . . . . .       4
     2.6    Title to Assets. . . . . . . . . . . . . . . . . . . . . .       5
     2.7    Accounts Receivable. . . . . . . . . . . . . . . . . . . .       5
     2.8    Equipment; Real Property Interests . . . . . . . . . . . .       6
     2.9    Proprietary Assets . . . . . . . . . . . . . . . . . . . .       6
     2.10   Contracts. . . . . . . . . . . . . . . . . . . . . . . . .       7
     2.11   Liabilities. . . . . . . . . . . . . . . . . . . . . . . .       9
     2.12   Compliance With Legal Requirements . . . . . . . . . . . .      10
     2.13   Governmental Authorizations. . . . . . . . . . . . . . . .      10
     2.14   Tax Matters. . . . . . . . . . . . . . . . . . . . . . . .      10
     2.15   Employee and Labor Matters; Benefit Plans. . . . . . . . .      11
     2.16   Environmental Matters. . . . . . . . . . . . . . . . . . .      14
     2.17   Bank Accounts. . . . . . . . . . . . . . . . . . . . . . .      14
     2.18   Insurance. . . . . . . . . . . . . . . . . . . . . . . . .      14
     2.19   Related Party Transactions . . . . . . . . . . . . . . . .      15
     2.20   Legal Proceedings; Orders. . . . . . . . . . . . . . . . .      15
     2.21   Authority; Binding Nature of Agreement . . . . . . . . . .      16
     2.22   NonContravention; Consents . . . . . . . . . . . . . . . .      16
     2.23   Full Disclosure. . . . . . . . . . . . . . . . . . . . . .      17
     2.24   Accounting Matters . . . . . . . . . . . . . . . . . . . .      17
     2.25   Brokers. . . . . . . . . . . . . . . . . . . . . . . . . .      17
     2.26   Consents . . . . . . . . . . . . . . . . . . . . . . . . .      17

3.   REPRESENTATIONS AND WARRANTIES OF THE PARTNERS AND DP . . . . . .      17
     3.1    Representations and Warranties . . . . . . . . . . . . . .      17

4.   REPRESENTATIONS AND WARRANTIES OF VISTA AND SUB . . . . . . . . .      18
     4.1    Due Organization; Qualification  . . . . . . . . . . . . .      18
     4.2    Charter Documents. . . . . . . . . . . . . . . . . . . . .      18
     4.3    Capitalization, etc. . . . . . . . . . . . . . . . . . . .      18
     4.4    SEC Filings; Financial Statements. . . . . . . . . . . . .      19
     4.5    Absence of Certain Changes or Events . . . . . . . . . . .      19
     4.6    Compliance with Legal Requirements . . . . . . . . . . . .      19
     4.7    Governmental Authorizations. . . . . . . . . . . . . . . .      20

                                       i
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     4.8    Legal Proceedings; Orders. . . . . . . . . . . . . . . . .      20
     4.9    Authority; Binding Nature of Agreement . . . . . . . . . .      20
     4.10   NonContravention; Consents . . . . . . . . . . . . . . . .      21
     4.11   Full Disclosure. . . . . . . . . . . . . . . . . . . . . .      21
     4.12   Accounting Matters . . . . . . . . . . . . . . . . . . . .      22
     4.13   Brokers. . . . . . . . . . . . . . . . . . . . . . . . . .      22

5.   PRE-CLOSING COVENANTS OF GEOSURE AND THE PARTNERS . . . . . . . .      22
     5.1    Access and Investigation . . . . . . . . . . . . . . . . .      22
     5.2    Operation of GEOSURE's Business. . . . . . . . . . . . . .      22
     5.3    Notification; Updates to GEOSURE Disclosure Schedule . . .      24
     5.4    No Negotiation . . . . . . . . . . . . . . . . . . . . . .      24
     5.5    Section 754 Election . . . . . . . . . . . . . . . . . . .      25

6.   PRE-CLOSING COVENANTS OF VISTA AND SUB. . . . . . . . . . . . . .      25
     6.1    Access and Investigation . . . . . . . . . . . . . . . . .      25
     6.2    Notification; Updates to VISTA Disclosure Schedule . . . .      25

7.   ADDITIONAL COVENANTS OF GEOSURE AND VISTA . . . . . . . . . . . .      26
     7.1    Filings and Consents . . . . . . . . . . . . . . . . . . .      26
     7.2    Public Announcements . . . . . . . . . . . . . . . . . . .      26
     7.3    Pooling of Interests . . . . . . . . . . . . . . . . . . .      27
     7.4    Affiliate Agreements . . . . . . . . . . . . . . . . . . .      27
     7.5    Best Efforts . . . . . . . . . . . . . . . . . . . . . . .      27
     7.6    Sanborn Agreement. . . . . . . . . . . . . . . . . . . . .      27
     7.7    Regulatory Approvals . . . . . . . . . . . . . . . . . . .      27
     7.8    Registration Rights. . . . . . . . . . . . . . . . . . . .      27
     7.9    FIRPTA Matters . . . . . . . . . . . . . . . . . . . . . .      32
     7.10   Treatment of Employee Plans and Benefits . . . . . . . . .      32
     7.11   Employee Indemnification . . . . . . . . . . . . . . . . .      32
     7.12   Tax Returns and Financial Statements . . . . . . . . . . .      32
     7.13   Capital Availability Agreement . . . . . . . . . . . . . .      32

8.   CONDITIONS PRECEDENT TO OBLIGATIONS OF VISTA AND SUB. . . . . . .      32
     8.1    Accuracy of Representations  . . . . . . . . . . . . . . .      32
     8.2    Performance of Covenants . . . . . . . . . . . . . . . . .      33
     8.3    No Distributions . . . . . . . . . . . . . . . . . . . . .      33
     8.4    Consents . . . . . . . . . . . . . . . . . . . . . . . . .      33
     8.5    Agreements and Documents . . . . . . . . . . . . . . . . .      33
     8.6    Compliance with the Securities Act . . . . . . . . . . . .      34
     8.7    No Restraints. . . . . . . . . . . . . . . . . . . . . . .      34
     8.8    No Legal Proceedings . . . . . . . . . . . . . . . . . . .      34
     8.9    GEOSURE's Key Employees. . . . . . . . . . . . . . . . . .      34
     8.10   Due Diligence. . . . . . . . . . . . . . . . . . . . . . .      34

                                       ii



<PAGE>


9.   CONDITIONS PRECEDENT TO OBLIGATIONS OF GEOSURE AND THE PARTNERS .      34
     9.1    Accuracy of Representations  . . . . . . . . . . . . . . .      34
     9.2    Performance of Covenants . . . . . . . . . . . . . . . . .      35
     9.3    Documents. . . . . . . . . . . . . . . . . . . . . . . . .      35
     9.4    No Restraints. . . . . . . . . . . . . . . . . . . . . . .      35
     9.5    Compliance with the Securities Act . . . . . . . . . . . .      35
     9.6    No Legal Proceedings . . . . . . . . . . . . . . . . . . .      35

10.  TERMINATION . . . . . . . . . . . . . . . . . . . . . . . . . . .      35
     10.1   Termination Events . . . . . . . . . . . . . . . . . . . .      35
     10.2   Termination Procedures . . . . . . . . . . . . . . . . . .      36
     10.3   Effect of Termination. . . . . . . . . . . . . . . . . . .      36

11.  SURVIVAL OF REPRESENTATIONS; INDEMNIFICATION. . . . . . . . . . .      37
     11.1   Survival of Representations, etc.  . . . . . . . . . . . .      37
     11.2   Indemnification. . . . . . . . . . . . . . . . . . . . . .      37
     11.3   Interest . . . . . . . . . . . . . . . . . . . . . . . . .      38
     11.4   Defense of Third Party Claims. . . . . . . . . . . . . . .      38
     11.5   Indemnity Escrow Fund. . . . . . . . . . . . . . . . . . .      39

12.  MISCELLANEOUS PROVISIONS. . . . . . . . . . . . . . . . . . . . .      39
     12.1   Further Assurances . . . . . . . . . . . . . . . . . . . .      39
     12.2   Fees and Expenses. . . . . . . . . . . . . . . . . . . . .      39
     12.3   Attorneys' Fees. . . . . . . . . . . . . . . . . . . . . .      39
     12.4   Notices. . . . . . . . . . . . . . . . . . . . . . . . . .      40
     12.5   Confidentiality. . . . . . . . . . . . . . . . . . . . . .      41
     12.6   Time of The Essence. . . . . . . . . . . . . . . . . . . .      41
     12.7   Headings . . . . . . . . . . . . . . . . . . . . . . . . .      41
     12.8   Counterparts . . . . . . . . . . . . . . . . . . . . . . .      41
     12.9   Governing Law. . . . . . . . . . . . . . . . . . . . . . .      41
     12.10  Successors and Assigns . . . . . . . . . . . . . . . . . .      41
     12.11  Remedies Cumulative; Specific Performance. . . . . . . . .      41
     12.12  Waiver . . . . . . . . . . . . . . . . . . . . . . . . . .      42
     12.13  Amendments . . . . . . . . . . . . . . . . . . . . . . . .      42
     12.14  Severability . . . . . . . . . . . . . . . . . . . . . . .      42
     12.15  Parties in Interest. . . . . . . . . . . . . . . . . . . .      42
     12.16  Entire Agreement . . . . . . . . . . . . . . . . . . . . .      42
     12.17  Construction . . . . . . . . . . . . . . . . . . . . . . .      42


                                       iii



<PAGE>


LIST OF EXHIBITS:
- -----------------

EXHIBIT A --   LIST OF PARTNERS

EXHIBIT B --   CERTAIN DEFINITIONS

EXHIBIT C  --  PARTNERSHIP INTEREST ASSIGNMENT

EXHIBIT D1 --  FORM OF AFFILIATE AGREEMENT

EXHIBIT D2 --  PERSONS TO EXECUTE AFFILIATE AGREEMENTS

EXHIBIT E --   ITEMS TO BE ADDRESSED IN LEGAL OPINION OF RUBIN BAUM LEVIN
               CONSTANT & FRIEDMAN, COUNSEL TO GEOSURE

EXHIBIT F --   ITEMS TO BE ADDRESSED IN LEGAL OPINION OF GRAY CARY WARE &
               FREIDENRICH, COUNSEL TO VISTA

EXHIBIT G  --  FORM OF ESCROW AGREEMENT


LIST OF SCHEDULES:
- ------------------

Schedule 4.3 -- VISTA Capitalization



<PAGE>



                      PARTNERSHIP INTEREST PURCHASE AGREEMENT
                                          
       THIS PARTNERSHIP INTEREST PURCHASE AGREEMENT ("Agreement") is made and 
entered into as of January 5, 1999, by and among VISTA INFORMATION SOLUTIONS, 
INC., a Delaware corporation ("VISTA"); VISTA Environmental Information, 
Inc., a Delaware corporation and a wholly owned subsidiary of VISTA ("SUB"); 
GEOSURE, L.P., a New York limited partnership ("GEOSURE"); and the partners 
of GEOSURE (and those persons who will become partners of GEOSURE prior to 
the Closing (as defined below)) identified on EXHIBIT A attached hereto (the 
"Partners"). Certain other capitalized terms used in this Agreement are 
defined in EXHIBIT B attached hereto.

                                       RECITALS

       A.  Under and subject to the terms of this Agreement, VISTA will 
acquire all of the general partner interests of GEOSURE and SUB will acquire 
all of the limited partner interests of GEOSURE from the Partners 
(collectively, the "Acquisition").

       B.  The parties intend that the Acquisition be treated as a "pooling 
of interests" for accounting purposes.

       C.  The Partners collectively own one hundred percent (100%) of the 
currently outstanding general partner interests and limited partner interests 
of GEOSURE. Prior to the Closing, Mr. Dan Prickett ("DP") may acquire certain 
general partnership interests and limited partnership interests of GEOSURE 
through the exercise of an option; thereafter EXHIBIT A will be revised and 
all references in this Agreement to the Partners as of and after the Closing 
shall include DP.

       D.  This Agreement has been approved by the Boards of Directors of 
VISTA and SUB and by the Partners.

                                      AGREEMENT

       NOW THEREFORE, in reliance on the foregoing and in and for the 
consideration and the mutual covenants set forth herein, the parties agree as 
follows:

1.     THE ACQUISITION

       1.1    SALE AND PURCHASE OF PARTNERSHIP INTEREST.  Subject to the 
terms and conditions set forth in this Agreement, at the Closing (as defined 
below), (i) the general partners of GAMMA shall sell all of their general 
partner interests in GEOSURE to VISTA, and VISTA shall purchase all such 
interests, and (ii) the limited partners of GAMMA shall sell all of their 
limited partner interests in GEOSURE to SUB, and SUB shall purchase all such 
interests.

       1.2    CLOSING.  The consummation of the transactions contemplated by 
this Agreement (the "Closing") shall take place at the offices of Gray Cary 
Ware & Freidenrich, 4365 Executive Drive, Suite 1600, San Diego, California 
92121, on January 12, 1999, or at such other time and

                                       1

<PAGE>


date as the Parties agree, but in no event later than the second business day 
after the date that all of the conditions set forth in Sections 8 and 9 have 
been satisfied or waived (the "Closing Date").  

       1.3    EFFECT OF THE ACQUISITION  The Acquisition shall have the 
effects set forth in this Agreement and in the applicable provisions of the 
New York Revised Limited Partnership Act.  Without limiting the generality of 
the foregoing, and subject thereto, at the Closing all of the property, 
rights, privileges, powers and franchises of GEOSURE shall remain vested in 
GEOSURE, and all debts, liabilities and duties of GEOSURE shall remain the 
debts, liabilities and duties of GEOSURE.

       1.4    EFFECT ON LIMITED PARTNERSHIP INTEREST.

              (a)    Subject to Section 1.4(b), at the Closing VISTA will 
issue to each general partner of GEOSURE, and SUB will issue to each limited 
partner of GEOSURE, in each case in exchange for a Partnership Interest 
Assignment in the form of EXHIBIT C attached hereto executed by such Partner, 
the number of shares of the common stock, par value $0.001 per share, of 
VISTA ("VISTA Common Stock") equal to the product of 2,590,000 (the "Exchange 
Shares") multiplied by the percentage of such partner's pro rata ownership 
interest of GEOSURE, as set forth on EXHIBIT A; provided that ten percent 
(10%) of the Exchange Shares allocated to each Partner shall be deposited 
into escrow in accordance with Section 11.5.

              (b)    No fractional shares of VISTA Common Stock shall be 
issued in connection with the Acquisition, and no certificates for any such 
fractional shares shall be issued.  In lieu of such fractional shares, any 
Partner who would otherwise be entitled to receive a fraction of a share of 
VISTA Common Stock shall, upon delivery of such Partner's Partnership 
Interest Assignment, be paid in cash the dollar amount (rounded to the 
nearest whole cent), without interest, determined by multiplying such 
fraction by Six Dollars and Fifty Cents ($6.50).

              (c)    VISTA and SUB shall be entitled to deduct and withhold 
from any consideration payable or otherwise deliverable to any Partner 
pursuant to this Agreement such amounts as VISTA or SUB may be required to 
deduct or withhold therefrom under the Internal Revenue Code of 1986, as 
amended (the "Code"), or under any provision of state, local or foreign tax 
law (or, in the alternative, VISTA and SUB may request tax information and 
other documentation to ensure no withholding is necessary).  To the extent 
such amounts are so deducted or withheld, such amounts shall be treated for 
all purposes under this Agreement as having been paid to the Partner to whom 
such amounts would otherwise have been paid.

       1.5    ACCOUNTING TREATMENT.  For accounting purposes, the Acquisition 
is intended to be treated as a "pooling of interests."

2.     REPRESENTATIONS AND WARRANTIES OF GEOSURE

       GEOSURE represents and warrants to VISTA and SUB that, except as set 
forth in the disclosure schedule which references the specific 
representations and warranties as to which the exception is made and which 
has been delivered by GEOSURE to VISTA and SUB on or before the date of this 
Agreement (the "GEOSURE Disclosure Schedule") (any items disclosed in the 
GEOSURE Disclosure Schedule being considered an exception to the other 
representations and


                                       2

<PAGE>


warranties not referenced therein if a reasonable business person who was not 
familiar with GEOSURE or its operations would reasonably expect such item to 
apply to such other representations or warranties): 

       2.1    ORGANIZATION, STANDING AND POWER.  GEOSURE is a limited 
partnership duly organized, validly existing and in good standing under the 
laws of New York, has all requisite power to own, lease and operate its 
assets and to carry on its business as currently being conducted and as 
currently proposed to be conducted, and is duly qualified to transact 
business and is in good standing in each jurisdiction in which the nature of 
its operations requires such qualification, except where the failure to so 
qualify has not and will not have a Material Adverse Effect on GEOSURE.  
GEOSURE has delivered to Vista true and correct copies of the partnership 
agreement of GEOSURE and the charter documents of each Subsidiary, all as 
amended to date.  GEOSURE and each of its Subsidiaries (each of GEOSURE and 
such Subsidiaries is individually referred to as the "Acquired Entity" and 
collectively as the "Acquired Entities"), is not in violation of any of the 
provisions of its charter documents.  Except as set forth in Part 2.1 of the 
GEOSURE Disclosure Schedule, GEOSURE does not directly or indirectly own any 
equity or similar interest in, or any interest convertible or exchangeable or 
exercisable for any equity or similar interest in, any corporation, 
partnership, joint venture or other business association or entity.

       2.2    PARTNERSHIP DOCUMENTS.  GEOSURE has furnished to VISTA, or its 
representatives, for its examination (i) copies of all records required to be 
set forth of all proceedings, consents, actions, and meetings of the limited 
and general partners and (ii) to the extent requested by VISTA, all permits, 
orders, and consents issued by any Governmental Body with respect to GEOSURE 
or any of its Subsidiaries.  The partnership records of GEOSURE are complete 
and accurate in all material respects, and the signatures of all officers and 
limited and general partners and other persons appearing on all documents 
contained therein are the true signatures of the persons purporting to have 
signed the same.  All actions reflected in such books and records were duly 
and validly taken in material compliance with the laws of the applicable 
jurisdiction.

       2.3    CAPITALIZATION, ETC. 

              (a)    The issued and outstanding interests of GEOSURE consist 
of partnership interests issued to the persons and in the relative amounts 
set forth on EXHIBIT A.  All of the outstanding partnership interests of 
GEOSURE have been duly authorized and validly issued, and are fully paid. 
GEOSURE has made available to VISTA an accurate and complete description of 
the terms of any repurchase option which is held by GEOSURE and to which any 
of such partnership interests are subject as well as any obligation by 
GEOSURE to pay distributions on any of its partnership interests.  Except for 
the option held by DP which will be exercised prior to the Closing, there are 
no rights or agreements outstanding for the issuance of additional 
partnership interests to any person.

              (b)    All outstanding partnership interests of GEOSURE have 
been issued and granted in compliance with (i) all applicable securities laws 
and other applicable Legal Requirements, and (ii) all requirements set forth 
in applicable Contracts. 


                                       3

<PAGE>


              (c)    Except as set forth in Part 2.3 of GEOSURE Disclosure 
Schedule, since December 31, 1996, GEOSURE has never repurchased, redeemed or 
otherwise reacquired any partnership interests or other securities of 
GEOSURE. All securities so reacquired by GEOSURE were reacquired in 
compliance with (i) the applicable provisions of all applicable Legal 
Requirements, and (ii) all requirements set forth in applicable Contracts. 

              (d)    Except as set forth in Part 2.3 of the GEOSURE 
Disclosure Schedule, all of the outstanding securities of each of the 
Subsidiaries are validly issued (in compliance with all applicable securities 
laws and other Legal Requirements and applicable GEOSURE Contracts), fully 
paid and nonassessable and are owned beneficially and of record by GEOSURE or 
its wholly owned Subsidiaries, free and clear of any Encumbrance.

       2.4    FINANCIAL STATEMENTS.  GEOSURE has delivered to VISTA its 
audited consolidated financial statements as of and for each of the years 
ended December 31, 1996, and 1997 and its unaudited consolidated financial 
statements for the nine months ended September 30, 1998 (collectively, the 
"GEOSURE Financial Statements").  The GEOSURE Financial Statements are 
correct in all material respects and were prepared in accordance with 
generally accepted accounting principles ("GAAP") applied on a consistent 
basis throughout the periods involved (except that the unaudited financial 
statements do not contain footnotes and are subject to normal and recurring 
year end audit adjustments, which will not, individually or in the aggregate, 
be material in magnitude). The GEOSURE Financial Statements present fairly 
the consolidated financial position of GEOSURE in all material respects as of 
the respective dates and the consolidated results of its operations and cash 
flows for the periods indicated. GEOSURE has maintained a standard system of 
accounting established and administered in accordance with good business 
practices sufficient to permit (i) the preparation of financial statements in 
accordance with GAAP, and (ii) an audit by independent accountants.

       2.5    ABSENCE OF CHANGES.  Except as set forth in Part 2.5 of the 
GEOSURE Disclosure Schedule, since September 30, 1998, GEOSURE has not: (a) 
suffered any change, or any development or combination of developments that 
has had or would reasonably be expected to have a Material Adverse Effect on 
GEOSURE, (b) suffered any damage, destruction or loss, whether or not covered 
by insurance, that has had or would reasonably be expected to have a Material 
Adverse Effect on GEOSURE; (c) granted any material increase in the 
compensation payable or to become payable by GEOSURE to its officers or 
employees other than increases in the ordinary course of business to 
employees who are not officers; (d) declared, set aside or paid any 
distribution on or in respect of its partnership interests or declared any 
direct or indirect redemption, retirement, purchase or other acquisition of 
such partnership interests; (e) issued any partnership interests or any 
rights for, or entered into any commitment relating to such partnership 
interests; (f) made any change in the accounting methods or practices it 
follows, whether for general financial or tax purposes, or any change in 
depreciation or amortization policies or rates; (g) sold, leased, abandoned 
or otherwise disposed of any real property, machinery, equipment or other 
operating property other than in the ordinary course of business; (h) sold, 
assigned, transferred, licensed or otherwise disposed of any patent, patent 
right, trademark, trade name, brand name, copyright (or pending application 
for any patent, trademark or copyright), invention, work of authorship, 
process, know-how, formula or trade secret or interest thereunder or other 
material intangible asset except for end-user license transactions


                                       4

<PAGE>


entered into in the ordinary course of its business pursuant to GEOSURE's 
standard forms of license agreement; (i) entered into any material commitment 
or transaction (including without limitation any borrowing) other than 
commitments or transactions entered into in the ordinary course of business 
that are not reasonably likely to have a Material Adverse Effect on GEOSURE; 
(j) permitted or allowed any of its property or assets to be subjected to any 
new mortgage, deed of trust, pledge, lien, security interest or other 
encumbrance of any kind, except for liens for current taxes not yet due and 
purchase money security interests incurred in the ordinary course of 
business; (k) made any capital expenditure or commitment for additions to 
property, plant or equipment individually in excess of $25,000, or, in the 
aggregate, in excess of $50,000; (l) paid, loaned or advanced any amount to, 
or sold, transferred or leased any properties or assets to, or entered into 
any agreement or arrangement with, any of its employees or partners or any 
affiliate of any of the foregoing, other than employee compensation and 
benefits and reimbursement of employment related business expenses incurred 
in the ordinary course of business; (m) suffered any material decrease in 
revenues from a customer which provided more than $50,000 in revenues during 
the 12 months prior to September 30, 1998 or determined that such a decrease 
should be expected; or (n) agreed to take any action described in this 
Section 2.5 or which would constitute a breach of any of the representations 
or warranties of GEOSURE contained in this Agreement.

       2.6    TITLE TO ASSETS. 

              (a)    Each of the Acquired Entities owns, and has good, valid 
and marketable title to, all assets purported to be owned by it, including: 
(i) all assets reflected on the GEOSURE Financial Statements; (ii) all assets 
referred to in Parts 2.1, 2.7 and 2.9 of GEOSURE Disclosure Schedule and all 
of its rights under the Contracts identified in Part 2.10 of GEOSURE 
Disclosure Schedule; and (iii) all other assets reflected in its books and 
records as being owned by such Acquired Entity. Except as set forth in Part 
2.6 of GEOSURE Disclosure Schedule, all of said assets are owned by the 
Acquired Entities free and clear of any liens or other Encumbrances, except 
for any lien for current taxes not yet due and payable.

              (b)    Part 2.6 of GEOSURE Disclosure Schedule identifies all 
assets that are material to the business of the Acquired Entities and that 
are being leased or licensed to any of the Acquired Entities.

       2.7    ACCOUNTS RECEIVABLE.  GEOSURE has provided to VISTA accurate 
records reflecting a breakdown and aging of all accounts receivable, notes 
receivable and other receivables of the Acquired Entities as of September 30, 
1998.  Except as set forth in Part 2.7 of GEOSURE Disclosure Schedule, all 
existing accounts receivable of the Acquired Entities (including those 
accounts receivable reflected on the Geosure Financial Statements that have 
not yet been collected and those accounts receivable that have arisen since 
September 30, 1998 and have not yet been collected) (i) represent valid 
obligations of customers of the Acquired Entities arising from bona fide 
transactions entered into in the ordinary course of business, and (ii) are 
current and will be collected in full when due, without any counterclaim or 
set off (net of the allowance for doubtful accounts included in such 
financial statements).


                                       5

<PAGE>


       2.8    EQUIPMENT; REAL PROPERTY INTERESTS.

              (a)    All items of equipment and other tangible assets owned 
by or leased to the Acquired Entities are adequate for the uses to which they 
are being put, are in good condition and repair (ordinary wear and tear 
excepted) and are adequate for the conduct of the Acquired Entities' 
businesses, in the manner in which such businesses are currently being 
conducted.

              (b)    None of the Acquired Entities own any real property or 
any interest in real property, except for the leasehold created under the 
real property leases identified in Part 2.10 of GEOSURE Disclosure Schedule.  

       2.9    PROPRIETARY ASSETS.

              (a)    Part 2.9(a)(i) of GEOSURE Disclosure Schedule sets 
forth, with respect to each GEOSURE Proprietary Asset registered with any 
Governmental Body or for which an application has been filed with any 
Governmental Body, (i) a brief description of such Proprietary Asset, and 
(ii) the names of the jurisdictions covered by the applicable registration or 
application. Part 2.9(a)(ii) of GEOSURE Disclosure Schedule identifies and 
provides a brief description of all other material GEOSURE Proprietary Assets 
owned by GEOSURE or any other Acquired Entity.  Part 2.9(a)(iii) of GEOSURE 
Disclosure Schedule identifies and provides a brief description of each 
material Proprietary Asset licensed to GEOSURE or any other Acquired Entity 
by any Person (except for any Proprietary Asset that is licensed to GEOSURE 
or any other Acquired Entity under any third party software license generally 
available to the public at a cost of less than $10,000), and identifies the 
license agreement under which such Proprietary Asset is being licensed to 
GEOSURE or any other Acquired Entity. Except as set forth in Part 2.9(a)(iv) 
of GEOSURE Disclosure Schedule GEOSURE (or any other Acquired Entity, as 
appropriate) has good, valid and marketable title to all of GEOSURE 
Proprietary Assets identified in Parts 2.9(a)(i) and 2.9(a)(ii) of GEOSURE 
Disclosure Schedule, free and clear of all liens and other Encumbrances, and 
has a valid right (contractual or otherwise) to use all Proprietary Assets 
identified in Part 2.9(a)(iii) of GEOSURE Disclosure Schedule.  Except as set 
forth in Part 2.9(a)(v) of GEOSURE Disclosure Schedule, no Acquired Entity is 
obligated to make any payment to any Person for the use of any GEOSURE 
Proprietary Asset.  Except as set forth in Part 2.9(a)(vi) of GEOSURE 
Disclosure Schedule, no Acquired Entity has developed jointly with any other 
Person any GEOSURE Proprietary Asset with respect to which such other Person 
has any rights. 

              (b)    The Acquired Entities have taken all measures and 
precautions reasonably necessary to protect and maintain the confidentiality 
and secrecy of all GEOSURE Proprietary Assets (except GEOSURE Proprietary 
Assets whose value would be unimpaired by public disclosure) and otherwise to 
maintain and protect the value of all GEOSURE Proprietary Assets.

              (c)    None of GEOSURE Proprietary Assets infringes or 
conflicts with any Proprietary Asset owned or used by any other Person.  None 
of the Acquired Entities is infringing, misappropriating or making any 
unlawful use of, and the Acquired Entities have not at any time infringed, 
misappropriated or made any unlawful use of, or received any notice or other 
communication (in writing or otherwise) of any actual, alleged, possible or 
potential infringement, misappropriation or unlawful use of, any Proprietary 
Asset owned or used by any


                                       6

<PAGE>


other Person.  To the best of the knowledge of GEOSURE, no other Person is 
infringing, misappropriating or making any unlawful use of, and no 
Proprietary Asset owned or used by any other Person infringes or conflicts 
with, any GEOSURE Proprietary Asset.

              (d)    Except as set forth in Part 2.9(d) of GEOSURE Disclosure 
Schedule: (i) each GEOSURE Proprietary Asset conforms in all material 
respects with any specification, documentation and performance standard 
provided with respect thereto by or on behalf of any Acquired Entity; and 
(ii) there has not been any material claim, which has not been fully 
resolved, by any customer or other Person alleging that any GEOSURE 
Proprietary Asset does not conform in all material respects with any 
specification, documentation, performance standard, representation or 
statement made or provided by or on behalf of any Acquired Entity, and, to 
the best of the knowledge of GEOSURE, there is no basis for any such claim.  
GEOSURE has established adequate reserves on the GEOSURE Financial Statements 
to cover all costs associated with any obligations that the Acquired Entities 
may have with respect to the correction or repair of programming errors or 
other defects in GEOSURE Proprietary Assets.

              (e)    GEOSURE Proprietary Assets constitute all the 
Proprietary Assets reasonably necessary to enable the Acquired Entities to 
conduct their businesses in the manner in which such businesses have been and 
are being conducted.  Except as set forth in Part 2.9(e) of GEOSURE 
Disclosure Schedule, (i) the Acquired Entities have not licensed any of 
GEOSURE Proprietary Assets to any Person on an exclusive basis, and (ii) the 
Acquired Entities have not entered into any covenant not to compete or 
Contract limiting the ability to exploit fully any Proprietary Assets or to 
transact business in any market or geographical area or with any Person. 

              (f)    Except as set forth in Part 2.9(f) of the GEOSURE 
Disclosure Schedule, (i) all current and former employees of the Acquired 
Entities have executed and delivered to the Acquired Entities an agreement 
that is substantially identical to the standard form of agreement used by 
GEOSURE and previously delivered to VISTA, and (ii) all current and former 
consultants and independent contractors to the Acquired Entities have 
executed and delivered to the Acquired Entities an agreement that is 
substantially identical to the standard form of agreement used by GEOSURE and 
previously delivered to VISTA.

              (g)    GEOSURE will retain all rights held by it to the Sanborn 
Maps as set forth in that certain agreement dated August 1, 1991 by and among 
Chadwyck-Healy, Ltd., Chadwyck-Healy, Inc., The Environmental Risk 
Information Center and Elsevier Realty Information Services (the "Sanborn 
Agreement"), and GEOSURE may assign such rights to VISTA following the 
Closing without restriction.  

       2.10   CONTRACTS.

              (a)    Part 2.10 of GEOSURE Disclosure Schedule identifies each 
Contract of GEOSURE or any of the other Acquired Entities material to the 
Acquired Entities, considered as a whole (each a "Material GEOSURE 
Contract"), including the following (to the extent material): 

                     (i)    each GEOSURE Contract relating to the employment 
of, or the performance of services by, any employee, consultant or 
independent contractor;


                                       7

<PAGE>


                     (ii)   each GEOSURE Contract relating to the 
acquisition, transfer, use, development, sharing or license of any 
Proprietary Asset;

                     (iii)  each GEOSURE Contract imposing any material 
restriction on any Acquired Entity's right or ability (A) to compete with any 
other Person, (B) to acquire any product or other asset or any services from 
any other Person, to sell any product or other asset to or perform any 
services for any other Person or to transact business with any other Person, 
or (C) develop or distribute any technology; 

                     (iv)   each GEOSURE Contract creating or involving any 
agency relationship, distribution arrangement or franchise relationship; 

                     (v)    each GEOSURE Contract relating to the creation of 
any Encumbrance with respect to any asset of any of the Acquired Entities; 

                     (vi)   each GEOSURE Contract involving or incorporating 
any guaranty, any pledge, any performance or completion bond, any indemnity 
or any surety arrangement;

                     (vii)  each GEOSURE Contract creating or relating to any 
partnership or joint venture or any sharing of revenues, profits, losses, 
costs or liabilities; 

                     (viii) each GEOSURE Contract relating to the purchase or 
sale of any product or other asset by or to, or the performance of any 
services by or for, any Related Party (as defined in Section 2.19);

                     (ix)   any other GEOSURE Contract that was entered into 
by any Acquired Entity outside the ordinary course of business or was 
inconsistent with any such Acquired Entity's past practices;

              (b)    The Acquired Entities have delivered to VISTA accurate 
and complete copies of all written Contracts identified in Part 2.10 of 
GEOSURE Disclosure Schedule, including all amendments thereto.  Each Contract 
identified in Part 2.10 of GEOSURE Disclosure Schedule is valid and in full 
force and effect, and is enforceable by the Acquired Entities in accordance 
with its terms, subject to (i) laws of general application relating to 
bankruptcy, insolvency and the relief of debtors, and (ii) rules of law 
governing specific performance, injunctive relief and other equitable 
remedies.

              (c)    Except as set forth in Part 2.10 of GEOSURE Disclosure 
Schedule:

                     (i)    none of the Acquired Entities has materially 
violated or breached, or committed any material default under, any GEOSURE 
Contract, and, to the best of the knowledge of GEOSURE, no other Person has 
materially violated or breached, or committed any material default under, any 
GEOSURE Contract; 

                     (ii)   to the best of the knowledge of GEOSURE, no event 
has occurred, and no circumstance or condition exists, that (with or without 
notice or lapse of time) will, or would reasonably be expected to, (A) result 
in a material violation or breach of any of the


                                       8

<PAGE>


provisions of any Material GEOSURE Contract, (B) give any Person the right to 
declare a default or exercise any remedy under any Material GEOSURE Contract, 
(C) give any Person the right to accelerate the maturity or performance of 
any Material GEOSURE Contract, or (D) give any Person the right to cancel, 
terminate or modify any Material GEOSURE Contract; 

                     (iii)  since December 31, 1997, none of the Acquired 
Entities has received any notice or other communication regarding any 
material violation or breach of, or default under, any GEOSURE Contract; and 

                     (iv)   none of the Acquired Entities has waived any of 
its material rights under any Material GEOSURE Contract.

              (d)    No Person is renegotiating any amount paid or payable to 
GEOSURE under any Material GEOSURE Contract or any other material term or 
provision of any Material GEOSURE Contract.

              (e)    The Contracts identified in Part 2.10 of GEOSURE 
Disclosure Schedule collectively constitute all of the Contracts reasonably 
necessary to enable the Acquired Entities to conduct their businesses in the 
manner in which they are currently being conducted.

              (f)    GEOSURE has made available to VISTA all material 
documentation regarding any bid, offer, award, written proposal or term sheet 
which has been submitted or received by the Acquired Entities since December 
31, 1997 and which could result in an agreement that would be a Material 
GEOSURE Contract.

              (g)    GEOSURE has made available to VISTA all material 
documentation regarding the Acquired Entities' current backlog under GEOSURE 
Contracts.

              (h)    Since December 31, 1996, except as set forth in Part 
2.10(h) of GEOSURE Disclosure Schedule, none of the Acquired Entities has 
entered into or become a party to a Government Contract.  

       2.11   LIABILITIES.  Except as disclosed in Part 2.5 of the GEOSURE 
Disclosure Schedule and except for obligations (such as, by way of 
illustration but not limitation, trade payables) arising in the ordinary 
course of business since September 30, 1998, none of the Acquired Entities 
has any accrued, contingent or other liabilities of any nature, either 
matured or unmatured (whether or not required to be reflected in financial 
statements in accordance with generally accepted accounting principles, and 
whether due or to become due), not otherwise reflected in GEOSURE Financial 
Statements or provided in GEOSURE Disclosure Schedule.  All sums advanced by 
certain partners under the Capital Availability Agreement with State Street 
Bank and Trust Company have been loans to GEOSURE, rather than contributions 
to the capital of GEOSURE.  The liabilities of GEOSURE for principal and 
accrued interest to State Street Bank and Trust Company and to certain 
Persons who advanced funds to GEOSURE in December 1998 (including prepayment 
penalties on such liabilities that will be incurred upon payment of such 
indebtedness by February 28, 1998) do not exceed an aggregate of $3,125,000 
and will not exceed that amount as of the Closing Date.


                                       9

<PAGE>


       2.12   COMPLIANCE WITH LEGAL REQUIREMENTS.  Each of the Acquired 
Entities is, and has at all times since December 31, 1996 been, in compliance 
with all applicable Legal Requirements, except where the failure to comply 
with such Legal Requirements has not had and will not have a Material Adverse 
Effect on GEOSURE.  Except as set forth in Part 2.12 of GEOSURE Disclosure 
Schedule, since December 31, 1996, none of the Acquired Entities has received 
any notice or other communication from any Governmental Body regarding any 
actual or possible violation of, or failure to comply with, any Legal 
Requirements, except where the failure to comply with such Legal Requirements 
has not had and will not have a Material Adverse Effect on GEOSURE.

       2.13   GOVERNMENTAL AUTHORIZATIONS.  Part 2.13 of GEOSURE Disclosure 
Schedule identifies each material Governmental Authorization held by each of 
the Acquired Entities.  The Governmental Authorizations identified in Part 
2.13 of GEOSURE Disclosure Schedule are valid and in full force and effect, 
and collectively constitute all Governmental Authorizations necessary to 
enable each of the Acquired Entities to conduct its business in the manner in 
which its business is currently being conducted except where any failure to 
have such Governmental Authorizations has not had and will not have a 
Material Adverse Effect on GEOSURE.  Each of the Acquired Entities is, and at 
all times since December 31, 1996 has been, in substantial compliance with 
the terms and requirements of the respective Governmental Authorizations 
identified in Part 2.13 of GEOSURE Disclosure Schedule.  Since December 31, 
1996, GEOSURE has not received any notice or other communication from any 
Governmental Body regarding (a) any actual or possible violation of or 
failure to comply with any term or requirement of any Governmental 
Authorization, or (b) any actual or possible revocation, withdrawal, 
suspension, cancellation, termination or modification of any Governmental 
Authorization.

       2.14   TAX MATTERS.

              (a)    All Tax Returns required to be filed by or on behalf of 
any Acquired Entity with any Governmental Body with respect to any taxable 
period ending on or before the Closing Date (the "GEOSURE Returns") (i) have 
been or will be filed on or before the applicable due date (including any 
extensions of such due date), and (ii) have been, or will be when filed, 
prepared in all material respects in compliance with all applicable Legal 
Requirements.  All amounts shown on GEOSURE Returns to be due on or before 
the Closing Date have been or will be paid on or before the Closing Date.  
GEOSURE has delivered or made available to VISTA accurate and complete copies 
of all GEOSURE Returns filed since December 31, 1995 which have been 
requested by VISTA.

              (b)    GEOSURE Financial Statements fully accrue all actual and 
contingent liabilities for Taxes with respect to all periods through the 
dates thereof in accordance with generally accepted accounting principles.

              (c)    Except as set forth in Part 2.14 of GEOSURE Disclosure 
Schedule, there have been no examinations or audits of any GEOSURE Return 
since December 31, 1995.  GEOSURE has delivered to VISTA accurate and 
complete copies of all audit reports and similar documents (to which it has 
access) relating to GEOSURE Returns.  Except as set forth in


                                       10

<PAGE>


Part 2.14 of GEOSURE Disclosure Schedule, no extension or waiver of the 
limitation period applicable to any of GEOSURE Returns has been granted and 
no such extension or waiver has been requested from any Acquired Entity.

              (d)    Except as set forth in Part 2.14 of GEOSURE Disclosure 
Schedule, since December 31, 1996 no material claim or Legal Proceeding is 
pending or has been threatened against or with respect to any Acquired Entity 
in respect of any Tax.  There are no unsatisfied liabilities for Taxes 
(including liabilities for interest, additions to tax and penalties thereon 
and related expenses) with respect to any notice of deficiency or similar 
document received by any Acquired Entity with respect to any Tax (other than 
liabilities for Taxes asserted under any such notice of deficiency or similar 
document which are being contested in good faith by any such Acquired Entity 
and with respect to which adequate reserves for payment have been 
established).  There are no liens for Taxes upon any of the assets of any 
Acquired Entity except liens for current Taxes not yet due and payable.  Each 
of the Acquired Entities has not entered into or become bound by any 
agreement or consent pursuant to Section 341(f) of the Code.  Each of the 
Acquired Entities has not been, and will not be, required to include any 
adjustment in taxable income for any tax period (or portion thereof) pursuant 
to Section 481 or 263A of the Code or any comparable provision under state or 
foreign Tax laws as a result of transactions or events occurring, or 
accounting methods employed, prior to the Closing.

              (e)    There is no agreement, plan, arrangement or other 
Contract covering any employee or independent contractor or former employee 
or independent contractor of any Acquired Entity that, considered 
individually or considered collectively with any other such Contracts, will, 
or could reasonably be expected to, give rise directly or indirectly to the 
payment of any amount that would not be deductible pursuant to Section 280G 
or Section 162 of the Code.  Each of the Acquired Entities is not, and has 
never been, a party to or bound by any tax indemnity agreement, tax sharing 
agreement, tax allocation agreement or similar Contract.

       2.15   EMPLOYEE AND LABOR MATTERS; BENEFIT PLANS.

              (a)    Part 2.15(a) of GEOSURE Disclosure Schedule identifies 
each salary, bonus, deferred compensation, incentive compensation, stock 
purchase, stock option, severance pay, or termination pay plan (collectively, 
the "Compensation Plans"), and each hospitalization, medical, life or other 
insurance, supplemental unemployment benefits, profit-sharing, pension or 
retirement plan, program or agreement (collectively, the "Plans") sponsored, 
maintained, contributed to or required to be contributed to by any Acquired 
Entity for the benefit of any employee of any Acquired Entity ("Employee"), 
except for Plans which would not require the Acquired Entities to make 
payments or provide benefits having a value in excess of $50,000 in the 
aggregate.

              (b)    Except as set forth in Part 2.15(a) of GEOSURE 
Disclosure Schedule, the Acquired Entities do not maintain, sponsor or 
contribute to, and, to the best of the knowledge of GEOSURE, have not at any 
time in the past maintained, sponsored or contributed to, any employee 
pension benefit plan (as defined in Section 3(2) of the Employee Retirement 
Income Security Act of 1974, as amended ("ERISA"), whether or not excluded 
from coverage under


                                       11

<PAGE>


specific Titles or Merger Subtitles of ERISA) for the benefit of Employees or 
former Employees (a "Pension Plan").

              (c)    Each of the Acquired Entities maintains, sponsors or 
contributes only to those employee welfare benefit plans (as defined in 
Section 3(1) of ERISA, whether or not excluded from coverage under specific 
Titles or Merger Subtitles of ERISA) for the benefit of Employees or former 
Employees which are described in Part 2.15(c) of GEOSURE Disclosure Schedule 
(the "Welfare Plans"), none of which is a multi-employer plan (within the 
meaning of Section 3(37) of ERISA).

              (d)    With respect to each Plan, GEOSURE has delivered to 
VISTA:

                     (i)    an accurate and complete copy of such Plan 
(including all amendments thereto);

                     (ii)   an accurate and complete copy of the annual 
report, if required under ERISA, with respect to such Plan for the last two 
years; 

                     (iii)  an accurate and complete copy of the most recent 
summary plan description, together with each Summary of Material 
Modifications, if required under ERISA, with respect to such Plan, and all 
material employee communications relating to such Plan;

                     (iv)   if such Plan is funded through a trust or any 
third party funding vehicle, an accurate and complete copy of the trust or 
other funding agreement (including all amendments thereto) and accurate and 
complete copies the most recent financial statements thereof;

                     (v)    accurate and complete copies of all Contracts 
relating to such Plan, including service provider agreements, insurance 
contracts, minimum premium contracts, stop-loss agreements, investment 
management agreements, subscription and participation agreements and record 
keeping agreements; and

                     (vi)   an accurate and complete copy of the most recent 
determination letter received from the Internal Revenue Service with respect 
to such Plan (if such Plan is intended to be qualified under Section 401(a) 
of the Code).

              (e)    No Acquired Entity is required to be, and, to the best 
of the knowledge of GEOSURE, has ever been required to be, treated as a 
single employer with any other Person under Section 4001(b)(1) of ERISA or 
Section 414(b), (c), (m) or (o) of the Code.  No Acquired Entity has ever 
been a member of an "affiliated service group" within the meaning of Section 
414(m) of the Code.  To the best of the knowledge of GEOSURE, the Acquired 
Entities have never made a complete or partial withdrawal from a 
multi-employer plan, as such term is defined in Section 3(37) of ERISA, 
resulting in "withdrawal liability," as such term is defined in Section 4201 
of ERISA (without regard to subsequent reduction or waiver of such liability 
under either Section 4207 or 4208 of ERISA).


                                       12

<PAGE>


              (f)    The Acquired Entities do not have any plan or commitment 
to create any additional Welfare Plan or any Pension Plan, or to modify or 
change any existing Welfare Plan or Pension Plan (other than to comply with 
applicable law) in a manner that would affect any Employee.

              (g)    Except as set forth in Part 2.15(g) of GEOSURE 
Disclosure Schedule, no Welfare Plan provides death, medical or health 
benefits (whether or not insured) with respect to any current or former 
Employee after any such Employee's termination of service (other than (i) 
benefit coverage mandated by applicable law, including coverage provided 
pursuant to Section 4980B of the Code, (ii) deferred compensation benefits 
accrued as liabilities on the GEOSURE Financial Statements, and (iii) 
benefits the full cost of which are borne by current or former Employees (or 
the Employees' beneficiaries)).

              (h)    With respect to each of the Welfare Plans constituting a 
group health plan within the meaning of Section 4980B(g)(2) of the Code, the 
provisions of Section 4980B of the Code ("COBRA") have been complied with in 
all material respects.

              (i)    Each of the Compensation Plans and the Plans has been 
operated and administered in all material respects in accordance with 
applicable Legal Requirements, including but not limited to ERISA and the 
Code.

              (j)    Each of the Compensation Plans and the Plans intended to 
be qualified under Section 401(a) of the Code has received a favorable 
determination from the Internal Revenue Service, GEOSURE is not aware of any 
reason why any such determination letter should be revoked.

              (k)    Except as set forth in Part 2.15(k) of GEOSURE 
Disclosure Schedule, neither the execution, delivery or performance of this 
Agreement, nor the consummation of the Acquisition or any of the other 
transactions contemplated by this Agreement, will result in any payment 
(including any bonus, golden parachute or severance payment) to any current 
or former Employee or director of any Acquired Entity (whether or not under 
any Plan), or materially increase the benefits payable under any Compensation 
Plan or Plan, or result in any acceleration of the time of payment or vesting 
of any such benefits.

              (l)    GEOSURE has provided to VISTA documentation showing all 
salaried employees of the Acquired Entities, and correctly reflecting, in all 
material respects, their salaries, any other compensation payable to them 
(including compensation payable pursuant to bonus, deferred compensation or 
commission arrangements), their dates of employment and their positions.  The 
Acquired Entities are not a party to any collective bargaining contract or 
other Contract with a labor union involving any of its Employees.  Except as 
set forth in Part 2.15(l) of the GEOSURE Disclosure Schedule, all of 
GEOSURE's employees are "at will" employees.

              (m)    Part 2.15(m) of GEOSURE Disclosure Schedule identifies 
each Employee who is not fully available to perform work because of 
disability or other leave and sets forth the basis of such leave and the 
anticipated date of return to full service.


                                       13

<PAGE>


              (n)    Each of the Acquired Entities is in compliance in all 
material respects with all applicable Legal Requirements and Contracts 
relating to employment, employment practices, wages, bonuses and terms and 
conditions of employment, including employee compensation matters.

              (o)    Except as set forth in Part 2.15(o) of GEOSURE 
Disclosure Schedule, each of the Acquired Entities has good labor relations, 
and GEOSURE has no reason to believe that (i) the consummation of the 
Acquisition or any of the other transactions contemplated by this Agreement 
will have a material adverse effect on any Acquired Entity's labor relations, 
or (ii) any Acquired Entity's employee(s) intend(s) to terminate his or her 
employment with the Acquired Entity.

       2.16   ENVIRONMENTAL MATTERS.  Each of the Acquired Entities is in 
compliance in all material  respects with all applicable Environmental Laws, 
which compliance includes the possession by each of the Acquired Entities of 
all permits and other Governmental Authorizations required under applicable 
Environmental Laws, and compliance with the terms and conditions thereof.  
Each of the Acquired Entities has not received any notice or other 
communication (in writing or otherwise), whether from a Governmental Body or 
citizens group, that alleges that any of the Acquired Entities is not in 
compliance with any Environmental Law, and, to the best of the knowledge of 
GEOSURE, there are no circumstances that may prevent or interfere with the 
Acquired Entities' compliance with any Environmental Law in the future.  To 
the best of the knowledge of GEOSURE, no current or prior owner of any 
property leased or controlled by any of the Acquired Entities has received 
any notice or other communication (in writing or otherwise), whether from a 
Government Body, citizens group, employee or otherwise, that alleges that 
such current or prior owner or any of the Acquired Entities is not in 
compliance with any Environmental Law.  All Governmental Authorizations 
currently held by each of the Acquired Entities pursuant to Environmental 
Laws are identified in Part 2.16 of GEOSURE Disclosure Schedule.  (For 
purposes of this Section 2.16: (i) "Environmental Law" means any federal, 
state, local or foreign Legal Requirement relating to pollution or protection 
of human health or the environment (including ambient air, surface water, 
ground water, land surface or subsurface strata), including any law or 
regulation relating to emissions, discharges, releases or threatened releases 
of Materials of Environmental Concern, or otherwise relating to the 
manufacture, processing, distribution, use, treatment, storage, disposal, 
transport or handling of Materials of Environmental Concern; and (ii) 
"Materials of Environmental Concern" include chemicals, pollutants, 
contaminants, wastes, toxic substances, petroleum and petroleum products and 
any other substance that is now or hereafter regulated by any Environmental 
Law.)

       2.17   BANK ACCOUNTS.  GEOSURE has provided to VISTA accurate records 
for each account (including account numbers) maintained by or for the benefit 
of any of the Acquired Entities at any financial institution and the persons 
authorized to draw on such accounts.

       2.18   INSURANCE.  Part 2.18 of GEOSURE Disclosure Schedule identifies 
all insurance policies maintained by, at the expense of or for the benefit of 
the Acquired Entities and identifies any material claims made thereunder, and 
GEOSURE has delivered or made available to VISTA accurate and complete copies 
of the insurance policies identified on Part 2.18 of GEOSURE Disclosure 
Schedule. Each of the insurance policies identified in Part 2.18 of GEOSURE 


                                       14

<PAGE>


Disclosure Schedule is in full force and effect.  Since December 31, 1996, 
each of the Acquired Entities has not received any notice or other 
communication regarding any actual or possible (a) cancellation or 
invalidation of any insurance policy, (b) refusal of any coverage or 
rejection of any claim under any insurance policy, or (c) material adjustment 
in the amount of the premiums payable with respect to any insurance policy.

       2.19   RELATED PARTY TRANSACTIONS.  Except as set forth in Part 2.19 
of the GEOSURE Disclosure Schedule, no Related Party has, and no Related 
Party has at any time since December 31, 1996 had, any direct or indirect 
interest in any material asset used in or otherwise relating to the 
businesses of the Acquired Entities; (b) no Related Party is, or has at any 
time since December 31, 1996 been, indebted to any of the Acquired Entities; 
(c) since December 31, 1996, no Related Party has entered into, or has had 
any direct or indirect financial interest in, any Material GEOSURE Contract, 
transaction or business dealing involving any of the Acquired Entities; (d) 
no Related Party is competing, or has at any time since December 31, 1996 
competed, directly or indirectly, with any of the Acquired Entities; and (e) 
no Related Party has any claim or right against any of the Acquired Entities 
(other than rights to receive compensation for services performed as an 
employee of any of the Acquired Entities).  (For purposes of this Section 
2.19 each of the following shall be deemed to be a "Related Party": (i) each 
of the GEOSURE Partners; (ii) each individual who is, or who has at any time 
since December 31, 1996 been, an officer, partner or manager of any of the 
Acquired Entities; (iii) each member of the immediate family of each of the 
individuals referred to in clauses "(i)" and "(ii)" above; and (iv) any trust 
or other Entity (other than the Acquired Entities) in which any one of the 
individuals referred to in clauses "(i)," "(ii)" and "(iii)" above holds (or 
in which more than one of such individuals collectively hold), beneficially 
or otherwise, a material voting, proprietary or equity interest. No Related 
Party shall have any liability or obligation to VISTA with respect to this 
Section 2.19.)

       2.20   LEGAL PROCEEDINGS; ORDERS.

              (a)    Except as set forth in Part 2.20 of GEOSURE Disclosure 
Schedule, GEOSURE has not been served with or otherwise received any 
documents initiating a Legal Proceeding, there is (to the best knowledge of 
GEOSURE) no pending Legal Proceeding, and (to the best of the knowledge of 
GEOSURE) no Person has threatened to commence any Legal Proceeding: (i) that 
involves any of the Acquired Entities or any of the assets owned or used by 
any of the Acquired Entities or (to the best knowledge of GEOSURE) any Person 
whose liability any of the Acquired Entities has or may have retained or 
assumed, either contractually or by operation of law; or (ii) that 
challenges, or that may have the effect of preventing, delaying, making 
illegal or otherwise interfering with, the Acquisition or any of the other 
transactions contemplated by this Agreement.  To the best of the knowledge of 
GEOSURE, except as set forth in Part 2.20 of GEOSURE Disclosure Schedule, no 
event has occurred, and no claim, dispute or other condition or circumstance 
exists, that will, or that could reasonably be expected to, give rise to or 
serve as a basis for the commencement of any such Legal Proceeding.

              (b)    Except as set forth in Part 2.20 of GEOSURE Disclosure 
Schedule, no material Legal Proceeding has been commenced by or has been 
pending against any of the Acquired Entities since December 31, 1996.


                                       15

<PAGE>


              (c)    There is no order, writ, injunction, judgment or decree 
to which any of the Acquired Entities, or any of the assets owned or used by 
any of the Acquired Entities, is subject.  To the best of the knowledge of 
GEOSURE, no employee of any of the Acquired Entities is subject to any order, 
writ, injunction, judgment or decree that prohibits such employee from 
engaging in or continuing any conduct, activity or practice relating to any 
such Acquired Entity's business.

       2.21   AUTHORITY; BINDING NATURE OF AGREEMENT.  Subject to the 
approval of the GEOSURE Partners, GEOSURE has the absolute and unrestricted 
right and authority to enter into and to perform its obligations under this 
Agreement; and the execution, delivery and performance by GEOSURE of this 
Agreement have been duly authorized by all necessary action on the part of 
GEOSURE and its general partners.  This Agreement constitutes the legal, 
valid and binding obligation of GEOSURE, enforceable against GEOSURE in 
accordance with its terms, subject to (i) laws of general application 
relating to bankruptcy, insolvency and the relief of debtors, and (ii) rules 
of law governing specific performance, injunctive relief and other equitable 
remedies.

       2.22   NON-CONTRAVENTION; CONSENTS.  Except as set forth in Part 2.22 
of GEOSURE Disclosure Schedule, neither (1) the execution, delivery or 
performance of this Agreement or any of the other agreements referred to in 
this Agreement, nor (2) the consummation of the Acquisition or any of the 
other transactions contemplated by this Agreement, will directly or 
indirectly (with or without notice or lapse of time):

              (a)    contravene, conflict with or result in a violation of 
(i) any of the provisions of GEOSURE's Limited Partnership Agreement, or (ii) 
any resolution adopted by GEOSURE's partners;

              (b)    contravene, conflict with or result in a violation of, 
or give any Governmental Body or other Person the right to challenge any of 
the transactions contemplated by this Agreement or to exercise any remedy or 
obtain any relief under, any material Legal Requirement or any order, writ, 
injunction, judgment or decree to which GEOSURE, or any of the assets owned 
or used by any of the Acquired Entities, is subject; 

              (c)    contravene, conflict with or result in a violation of 
any of the terms or requirements of, or give any Governmental Body the right 
to revoke, withdraw, suspend, cancel, terminate or modify, any material 
Governmental Authorization that is held by any of the Acquired Entities or 
that otherwise relates to any of the Acquired Entities' business or to any of 
the assets owned or used by any of the Acquired Entities; 

              (d)    contravene, conflict with or result in a violation or 
breach of, or result in a default under, any provision of any GEOSURE 
Contract that is or would constitute a Material GEOSURE Contract, or give any 
Person the right to (i) declare a default or exercise any remedy under any 
such GEOSURE Contract, (ii) accelerate the maturity or performance of any 
such GEOSURE Contract, or (iii) cancel, terminate or modify any such GEOSURE 
Contract; or 

              (e)    result in the imposition or creation of any lien or 
other Encumbrance upon or with respect to any asset owned or used by any of 
the Acquired Entities (except for minor


                                       16

<PAGE>


liens that will not, in any case or in the aggregate, materially detract from 
the value of the assets subject thereto or materially impair the operations 
of any such Acquired Entity).  Except as set forth in Part 2.22 of GEOSURE 
Disclosure Schedule or for those filings, notice or Consents the failure of 
which to make or obtain would not have a Material Adverse Effect on GEOSURE, 
the Acquired Entities are not and will not be required to make any filing 
with or give any notice to, or to obtain any Consent from, any Person in 
connection with (x) the execution, delivery or performance of this Agreement 
or any of the other agreements referred to in this Agreement, or (y) the 
consummation of the Acquisition or any of the other transactions contemplated 
by this Agreement.

       2.23   FULL DISCLOSURE.  This Agreement (including GEOSURE Disclosure 
Schedule) does not (i) contain any representation, warranty or information 
that is false or misleading with respect to any material fact, or (ii) omit 
to state any material fact or necessary in order to make the representations, 
warranties and information contained and to be contained herein and therein 
(in the light of the circumstances under which such representations, 
warranties and information were or will be made or provided) not false or 
misleading.

       2.24   ACCOUNTING MATTERS.  To the knowledge of GEOSURE, based on 
consultation with its independent accountants, neither GEOSURE nor any of its 
affiliates has taken or agreed to, or plans to, take any action that would 
prevent VISTA from accounting for the Acquisition as a "pooling of interests."

       2.25   BROKERS.  No broker, finder or financial adviser retained by 
GEOSURE is entitled to any brokerage, finder's or other fee or commission 
from GEOSURE in connection with the transactions contemplated by this 
Agreement.

       2.26   CONSENTS.  GEOSURE consents to the assignment of the 
partnership interests by each Partner and DP pursuant to the terms of this 
Agreement.

3.     REPRESENTATIONS AND WARRANTIES OF THE PARTNERS AND DP.

       3.1    REPRESENTATIONS AND WARRANTIES.  The Partners and DP (each, a 
"Transferor"), severally and not jointly, represent and warrant to VISTA and 
SUB that:

              (a)    to the best knowledge of such Transferor, the 
representations and warranties of GEOSURE contained herein (as qualified by 
GEOSURE Disclosure Schedule) are true and correct in all material respects, 
and do not set forth facts that are false or misleading in any material 
respect, nor do they omit to set forth facts the absence of which would make 
such representations and warranties materially false or misleading.  

              (b)    The respective Transferor has full right, power, legal 
capacity and authority to enter into and perform his or her obligations under 
this Agreement and the other related agreements to which he or she is a 
party. Subject to approval of the transfers from State Street Bank and Trust 
Company, no authorization or approval is necessary in order to enable such 
Transferor to enter into and perform the terms of this Agreement or the other 
related agreements to which he, she or it may be a party.  This Agreement is, 
and the other related


                                       17

<PAGE>


agreements when executed and delivered by the Transferor shall be, valid and 
binding obligations of the Partner enforceable in accordance with their 
respective terms.

              (c)    The Transferor has full right, title and interest to the 
GEOSURE partnership interests being sold by such Transferors, without any 
liens, encumbrances or adverse claims, except for encumbrances held by State 
Street Bank and Trust Company disclosed in Part 2.3(a) of the GEOSURE 
Disclosure Schedule.  Upon consummation of the transactions contemplated by 
this Agreement, the Transferor shall have no right to any ownership interest 
or rights to acquire an ownership interest of GEOSURE.

              (d)    The Transferor consents to the assignment by the other 
Transferors of their respective GEOSURE partnership interests to VISTA and 
SUB.

              (e)    The Transferor is acquiring the Exchange Shares for 
investment for the Transferor's own account.  The Transferor is an accredited 
investor as defined in Rule 501(a) of Regulation D promulgated under the 
Securities Act.  

              (f)    The Transferor understands that the Exchange Shares have 
not been registered under the Securities Act, by reason of a specific 
exemption from the registration provisions which depends upon, among other 
things, the bona fide nature of the investment intent and the accuracy of the 
Transferor's representations as expressed herein.  The Transferor understands 
that the Exchange Shares are "restricted securities" under applicable U.S. 
federal and state securities laws and that, pursuant to these laws, the 
Transferor must hold the Exchange Shares until such transfer is registered 
under the Securities Act and qualified by state authorities, or an exemption 
from such registration and qualification requirements is available.  The 
Transferor understands that the certificates evidencing the Exchange Shares 
will bear a legend in substantially the following form:  "THE SECURITIES 
REPRESENTED BY THIS CERTIFICATE HAVE NOT BEEN REGISTERED UNDER THE SECURITIES 
ACT OF 1933.  NO SALE OR DISTRIBUTION OF THESE SECURITIES MAY BE EFFECTED 
UNLESS SUBJECT TO AN EFFECTIVE REGISTRATION STATEMENT OR PURSUANT TO AN 
EXEMPTION FROM SUCH REGISTRATION."

4.     REPRESENTATIONS AND WARRANTIES OF VISTA AND SUB.

       VISTA and SUB represent and warrant to GEOSURE and each of the 
Partners that, except as set forth in the disclosure schedule prepared by the 
VISTA and delivered by the VISTA to GEOSURE on or before the date of this 
Agreement (the "VISTA Disclosure Schedule"):

       4.1    DUE ORGANIZATION; QUALIFICATION.

              (a)    VISTA and SUB are each duly organized, validly existing 
and in good standing under the laws of the State of Delaware and have all 
necessary power and authority: (i) to conduct their respective businesses in 
the manner in which such business is currently being conducted; (ii) to own 
and use their respective assets in the manner in which such assets are 
currently owned and used; and (iii) to perform their respective obligations 
under all Material VISTA Contracts by which they are or will be bound. 


                                       18

<PAGE>

              (b)    VISTA and SUB are qualified, authorized, registered or 
licensed to do business as a foreign entity in any jurisdiction where so 
required under applicable law, except where the failure to be so qualified, 
authorized, registered or licensed has not had and will not have a Material 
Adverse Effect on VISTA or SUB.  VISTA and SUB are in good standing as a 
foreign entity in each of such jurisdictions.

       4.2    CHARTER DOCUMENTS.  True, correct and complete copies of the 
charter documents, as amended to date, of VISTA and SUB have been provided to 
GEOSURE.  The charter documents of VISTA and SUB are in full force and 
effect. VISTA and SUB are not in violation of any provision of their 
respective charter documents.

       4.3    CAPITALIZATION, ETC.  The authorized and issued capital stock 
of VISTA is as set forth on Schedule 4.3 attached hereto.  All of the 
outstanding shares of VISTA capital stock have been duly authorized and 
validly issued, and are fully paid and nonassessable, and none of such shares 
is subject to any repurchase option or restriction on transfer other than 
restrictions imposed by federal or state securities laws.  All outstanding 
shares of VISTA capital stock have been issued in compliance with all 
applicable securities laws and other applicable Legal Requirements, and all 
requirements set forth in applicable Contracts.  As of December 30, 1998, 
VISTA had outstanding options to purchase 1,515,457 shares of common stock as 
of the date hereof and warrants to acquire 622,315 shares of common stock or 
securities convertible into common stock.  The Exchange Shares to be issued 
in the Acquisition, when issued by VISTA and SUB in accordance with the terms 
of this Agreement, will be duly authorized, validly issued, fully paid and 
nonassessable, will be issued in compliance with all applicable federal and 
state securities laws and, except for the restrictions imposed by applicable 
federal and state securities laws, will be free and clear of any Encumbrances 
created or imposed, directly or indirectly, by VISTA or SUB (subject to the 
terms of Affiliate Agreements (as defined below) entered into as contemplated 
by this Agreement).

       4.4    SEC FILINGS; FINANCIAL STATEMENTS. 

              (a)    VISTA has delivered or made available to GEOSURE 
accurate and complete copies (excluding copies of exhibits) of each report, 
registration statement (on a form other than Form S-8) and definitive proxy 
statement filed by VISTA with the SEC between January 1, 1998 and the date of 
this Agreement (the "VISTA SEC Documents").  As of the time it was filed with 
the SEC (or, if amended or superseded by a filing prior to the date of this 
Agreement, then on the date of such filing): (i) each of the VISTA SEC 
Documents complied in all material respects with the applicable requirements 
of the Securities Act or the Exchange Act (as the case may be); and (ii) none 
of the VISTA SEC Documents contained any untrue statement of a material fact 
or omitted to state a material fact required to be stated therein or 
necessary in order to make the statements therein, in the light of the 
circumstances under which they were made, not misleading.

              (b)    The consolidated financial statements contained in the 
VISTA SEC Documents: (i) complied as to form in all material respects with 
the published rules and regulations of the SEC applicable thereto; (ii) were 
prepared in accordance with generally accepted accounting principles applied 
on a consistent basis throughout the periods covered, 

                                   19

<PAGE>

except as may be indicated in the notes to such financial statements and (in 
the case of unaudited statements) as permitted by Form 10-QSB of the SEC, and 
except that unaudited financial statements may not contain footnotes and are 
subject to year end audit adjustments; and (iii) fairly present the 
consolidated financial position of VISTA and its subsidiaries as of the 
respective dates thereof and the consolidated results of operations of VISTA 
and its subsidiaries for the periods covered thereby.

       4.5    ABSENCE OF CERTAIN CHANGES OR EVENTS.  Since September 30, 
1998, there has not been (a) any change, or any development or combination of 
developments, that has had or would reasonably be expected to have a Material 
Adverse Effect on VISTA or SUB, or (b) any damage, destruction or loss, 
whether or not covered by insurance, that has had or would reasonably be 
expected to have a Material Adverse Effect on VISTA or SUB.

       4.6    COMPLIANCE WITH LEGAL REQUIREMENTS.  VISTA and SUB are, and 
have at all times since December 31, 1996 been, in compliance with all 
applicable Legal Requirements, except where the failure to comply with such 
Legal Requirements has not had and will not have a Material Adverse Effect on 
VISTA or SUB.  Since December 31, 1996, neither VISTA nor SUB has received 
any notice or other communication from any Governmental Body regarding any 
actual or possible violation of, or failure to comply with, any Legal 
Requirements, except where the failure to comply with such Legal Requirements 
has not had and will not have a Material Adverse Effect on VISTA or SUB.

       4.7    GOVERNMENTAL AUTHORIZATIONS.  The Governmental Authorizations 
held by VISTA are valid and in full force and effect, and collectively 
constitute all Governmental Authorizations necessary to enable VISTA and SUB 
to conduct their respective businesses in the manner in which such business 
is currently being conducted except where any failure to have such 
Governmental Authorizations has not had and will not have a Material Adverse 
Effect on VISTA or SUB.  VISTA and SUB are in substantial compliance with the 
terms and requirements of such Governmental Authorizations.

       4.8    LEGAL PROCEEDINGS; ORDERS. 

              (a)    Except as set forth in the VISTA SEC Documents, there is 
no pending Legal Proceeding, and (to the best of the knowledge of VISTA or 
SUB) no Person has threatened to commence any Legal Proceeding that has had 
or would reasonably be expected to have a Material Adverse Effect on VISTA or 
SUB: (i) that involves VISTA or SUB or any of the assets owned or used by 
VISTA or SUB or (to the best knowledge of VISTA or SUB) any Person whose 
liability VISTA or SUB has or may have retained or assumed, either 
contractually or by operation of law; or (ii) that challenges, or that may 
have the effect of preventing, delaying, making illegal or otherwise 
interfering with, the Acquisition or any of the other transactions 
contemplated by this Agreement.  To the best of the knowledge of VISTA or 
SUB, except as set forth in the VISTA SEC Documents, no event has occurred, 
and no claim, dispute or other condition or circumstance exists, that will, 
or that could reasonably be expected to, give rise to or serve as a basis for 
the commencement of any such Legal Proceeding.

                                       20

<PAGE>

              (b)    Except as set forth in the VISTA SEC Documents, no 
material Legal Proceeding has been commenced by or has been pending against 
any of the Acquiring Entities since December 31, 1997. 

              (c)    There is no order, writ, injunction, judgment or decree 
to which VISTA or SUB, or any of the assets owned or used by VISTA or SUB, is 
subject.  To the best of the knowledge of VISTA and SUB, no officer or other 
employee of VISTA or SUB is subject to any order, writ, injunction, judgment 
or decree that prohibits such officer or other employee from engaging in or 
continuing any conduct, activity or practice relating to the business of 
VISTA or SUB.

       4.9    AUTHORITY; BINDING NATURE OF AGREEMENT.  Each of VISTA and SUB 
has the absolute and unrestricted right and authority to perform their 
obligations under this Agreement; and the execution, delivery and performance 
by VISTA and SUB of this Agreement (including the contemplated issuance of 
VISTA Common Stock in the Acquisition in accordance with this Agreement) have 
been duly authorized by all necessary action on the part of VISTA, SUB and 
their respective Boards of Directors.  Upon conversion to Common Stock of 
certain shares of VISTA Preferred Stock, as to which VISTA has received oral 
commitments, no vote of VISTA's stockholders is needed to approve the 
Acquisition.  This Agreement constitutes the legal, valid and binding 
obligation of VISTA and SUB, enforceable against it in accordance with its 
terms, subject to (i) laws of general application relating to bankruptcy, 
insolvency and the relief of debtors, and (ii) rules of law governing 
specific performance, injunctive relief and other equitable remedies.

       4.10   NON-CONTRAVENTION; CONSENTS.  Neither (1) the execution, 
delivery or performance of this Agreement or any of the other agreements 
referred to in this Agreement, nor (2) the consummation of the Acquisition or 
any of the other transactions contemplated by this Agreement, will directly 
or indirectly (with or without notice or lapse of time):

              (a)    contravene, conflict with or result in a violation of 
(i) any of the provisions of the charter documents of VISTA or SUB, or (ii) 
any resolution adopted by the Board of Directors of VISTA or SUB, 
respectively;

              (b)    contravene, conflict with or result in a violation of, 
or give any Governmental Body or other Person the right to challenge any of 
the transactions contemplated by this Agreement or to exercise any remedy or 
obtain any relief under, any material Legal Requirement or any order, writ, 
injunction, judgment or decree to which VISTA or SUB, or any of their 
respective assets owned or used by it, is subject;

              (c)    contravene, conflict with or result in a violation of 
any of the terms or requirements of, or give any Governmental Body the right 
to revoke, withdraw, suspend, cancel, terminate or modify, any material 
Governmental Authorization that is held by VISTA or SUB or that otherwise 
relates to the business of VISTA or SUB or to any of the assets owned or used 
by them; 

              (d)    contravene, conflict with or result in a violation or 
breach of, or result in a default under, any provision of any Contract 
material to VISTA or SUB, or give any Person the 

                                       21

<PAGE>

right to (i) declare a default or exercise any remedy under any such 
Contract, (ii) accelerate the maturity or performance of any such Contract, 
or (iii) cancel, terminate or modify any such Contract; or 

              (e)    result in the imposition or creation of any lien or 
other Encumbrance upon or with respect to any asset owned or used by VISTA or 
SUB (except in each case for minor liens that will not, in any case or in the 
aggregate, materially detract from the value of the assets subject thereto or 
materially impair the operations of any such Acquiring Entity).  Except as 
may be required by the Securities Act, the Exchange Act, state securities or 
"blue sky" laws, and the Nasdaq Rules and Regulations, neither VISTA nor SUB 
will be required to make any filing with or give any notice to, or to obtain 
any Consent from, any Person in connection with (x) the execution, delivery 
or performance of this Agreement or any of the other agreements referred to 
in this Agreement, or (y) the consummation of the Acquisition or any of the 
other transactions contemplated by this Agreement.

       4.11   FULL DISCLOSURE.  This Agreement (including the VISTA 
Disclosure Schedule) does not (i) contain any representation, warranty or 
information that is false or misleading with respect to any material fact, or 
(ii) omit to state any material fact necessary in order to make the 
representations, warranties and information contained and to be contained 
herein and therein (in the light of the circumstances under which such 
representations, warranties and information were or will be made or provided) 
not false or misleading.

       4.12   ACCOUNTING MATTERS.  To the knowledge of VISTA, VISTA has not 
taken and has not agreed, and does not plan, and will not take any action 
that would prevent VISTA from accounting for the business combination to be 
effected by the Acquisition as a "pooling of interests."

       4.13   BROKERS.  No broker, finder or financial adviser retained by 
VISTA or SUB is entitled to any brokerage, finder's or other fee or 
commission from VISTA or SUB in connection with the transactions contemplated 
by this Agreement.

5.     PRE-CLOSING COVENANTS OF GEOSURE AND THE PARTNERS

       5.1    ACCESS AND INVESTIGATION.  During the period from the date of 
this Agreement through the Effective Time (the "Pre-Closing Period"), GEOSURE 
shall, and shall cause its Representatives to: (A) provide VISTA and VISTA's 
Representatives with reasonable access to GEOSURE's Representatives, 
personnel and assets and to all existing books, records, Tax Returns, work 
papers and other documents and information relating to GEOSURE; and (B) 
provide VISTA and VISTA's Representatives with copies of such existing books, 
records, Tax Returns, work papers and other documents and information 
relating to GEOSURE, and with such additional financial, operating and other 
data and information regarding GEOSURE, as VISTA may reasonably request.

       5.2    OPERATION OF GEOSURE'S BUSINESS.  During the Pre-Closing 
Period, except pursuant to prior written consent of VISTA, GEOSURE shall, and 
shall cause each of the other Acquired  Corporations to:

                                       22
<PAGE>

              (a)    conduct its business and operations in the ordinary 
course and in substantially the same manner as such business and operations 
have been conducted prior to the date of this Agreement, except as may be 
otherwise required by the Sanborn Agreement;

              (b)    in each case, in all material respects use reasonable 
efforts to preserve intact its current business organization, keep available 
the services of its current officers and employees and maintain its relations 
and good will with all suppliers, customers, landlords, creditors, employees 
and other Persons having business relationships with it;

              (c)    use reasonable efforts to keep in full force all 
insurance policies identified in Part 2.18 of GEOSURE Disclosure Schedule;

              (d)    not declare, accrue, set aside or pay any dividend or 
make any other distribution in respect of any of its securities, and shall 
not repurchase, redeem or otherwise reacquire any of its securities;

              (e)    not sell, issue or authorize the issuance of (i) any 
securities, (ii) any option or right to acquire any securities, or (iii) any 
instrument convertible into or exchangeable for any securities;

              (f)    except as otherwise provided herein, not amend or permit 
the adoption of any amendment to GEOSURE's Limited Partnership Agreement, or 
effect or permit GEOSURE to become a party to any Acquisition Transaction, 
recapitalization, reclassification of its limited partnership interests or 
similar transaction; to which each of the GEOSURE Partners also covenants;

              (g)    not form any subsidiary or acquire any equity interest 
or other interest in any other Entity;

              (h)    not make any capital expenditure, except for capital 
expenditures that, when added to all other capital expenditures made on 
behalf of the Acquired Entities during the Pre-Closing Period, do not exceed 
$50,000 in the aggregate; 

              (i)    not (i) enter into, or permit any of the assets owned or 
used by it to become bound by, any Contract that is or would constitute a 
Material GEOSURE Contract, or (ii) amend or prematurely terminate, or waive 
any material right or remedy under, any such Material GEOSURE Contract;

              (j)    except in compliance with the limits of subsection (i) 
above, not (i) acquire, lease or license any right or other asset from any 
other Person, (ii) sell or otherwise dispose of, or lease or license, any 
right or other asset to any other Person, or (iii) waive or relinquish any 
right, except for assets acquired, leased, licensed or disposed of by the 
Acquired Entities pursuant to Contracts that are not Material GEOSURE 
Contracts;

              (k)    not (i) lend money to any Person or (ii) incur or 
guarantee any indebtedness for borrowed money (except that GEOSURE may make 
routine borrowings in the ordinary course of business under its line of 
credit with State Street Bank & Trust Company) and 

                                       23
<PAGE>

from its partners to fund payments due to said bank and otherwise provide 
working capital to GEOSURE;

              (l)    except as set forth in GEOSURE Disclosure Schedule, not 
(i) establish, adopt or amend any Employee Benefit Plan, (ii) pay any bonus 
or make any profit-sharing payment, cash incentive payment or similar payment 
to, or increase the amount of the wages, salary, commissions, fringe benefits 
or other compensation or remuneration payable to, any of its directors, 
officers or employees, except for items accrued and approved by VISTA or 
pursuant to agreements in effect on the date hereof, or in accordance with 
GEOSURE's past practices, or (iii) hire any new employee whose aggregate 
annual compensation from GEOSURE is expected to exceed $60,000;

              (m)    not change any of its methods of accounting or 
accounting practices in any material respect; 

              (n)    not make any Tax election;

              (o)    not commence or settle any material Legal Proceeding; and

              (p)    not agree or commit to take any of the actions described 
in clauses "(d)" through "(o)" above.

       5.3    NOTIFICATION; UPDATES TO GEOSURE DISCLOSURE SCHEDULE.

              (a)    During the Pre-Closing Period, GEOSURE shall promptly 
notify VISTA in writing of:

                     (i)    the discovery by GEOSURE of any event, condition, 
fact or circumstance that occurred or existed on or prior to the date of this 
Agreement and that caused or constitutes an inaccuracy in or breach of any 
representation or warranty made by GEOSURE or any of the Partners in this 
Agreement;

                     (ii)   any event, condition, fact or circumstance that 
occurs, arises or exists after the date of this Agreement and that would 
cause or constitute an inaccuracy in or breach of any representation or 
warranty made by GEOSURE or any of the Partners in this Agreement if (A) such 
representation or warranty had been made as of the time of the occurrence, 
existence or discovery of such event, condition, fact or circumstance, or (B) 
such event, condition, fact or circumstance had occurred, arisen or existed 
on or prior to the date of this Agreement;

                     (iii)  any breach of any covenant or obligation of 
GEOSURE (and each Partner shall promptly notify VISTA in writing of any 
breach of any covenant or obligation of such Partner set forth herein); and

                     (iv)   any event, condition, fact or circumstance that 
would make the timely satisfaction of any of the conditions set forth in 
Section 8 or Section 9 impossible or unlikely.

                                       24
<PAGE>

              (b)    If any event, condition, fact or circumstance that is 
required to be disclosed pursuant to Section 5.3(a) requires any change in 
GEOSURE Disclosure Schedule, or if any such event, condition, fact or 
circumstance would require such a change assuming GEOSURE Disclosure Schedule 
were dated as of the date of the occurrence, existence or discovery of such 
event, condition, fact or circumstance, then GEOSURE shall promptly deliver 
to VISTA an update to GEOSURE Disclosure Schedule specifying such change.  No 
such update shall be deemed to supplement or amend the GEOSURE Disclosure 
Schedule for the purpose of (i) determining the accuracy of any of the 
representations and warranties made by GEOSURE or any of the Partners in this 
Agreement, or (ii) determining whether any of the conditions set forth in 
Section 8 has been satisfied; provided, however, that if Closing occurs, the 
GEOSURE Disclosure Schedule shall be deemed to be modified at such time by 
such update.

       5.4    NO NEGOTIATION.  Neither GEOSURE nor any of the Partners shall, 
directly or indirectly:

              (a)    solicit or encourage the initiation of any inquiry, 
proposal or offer from any Person (other than VISTA) relating to a possible 
Acquisition Transaction;

              (b)    participate in any discussions or negotiations or enter 
into any agreement with, or provide any nonpublic information or afford 
access to the properties, books or records of GEOSURE to any Person (other 
than VISTA) relating to or in connection with a possible Acquisition 
Transaction; or

              (c)    consider, entertain or accept (subject to Section 
10.1(e)) any proposal or offer from any Person (other than VISTA) relating to 
a possible Acquisition Transaction.

       The parties acknowledge that any breach of the foregoing provisions by 
any officer, director or agent (including any employee of GEOSURE acting as 
agent) of any of the Acquired Entities shall be deemed a breach by GEOSURE.

       This Section 5.4 does not prohibit GEOSURE from furnishing information 
regarding GEOSURE or entering into discussions with any Person in response to 
an unsolicited bona fide written proposal or offer relating to a possible 
Acquisition Transaction submitted by such Person if the General Partners of 
GEOSURE conclude in good faith, after consultation with outside legal 
counsel, that such action is required in order for the General Partners of 
GEOSURE to comply with their fiduciary obligations to the Partners under 
applicable law.

GEOSURE shall promptly notify VISTA in writing of any inquiry, proposal or 
offer relating to a possible Acquisition Transaction that is received by 
GEOSURE or any of the Partners during the Pre-Closing Period.

       5.5    SECTION 754 ELECTION.  GEOSURE will file an election under 
section 754 of the Code and under similar provisions of applicable state tax 
laws.

                                       25
<PAGE>

6.     PRE-CLOSING COVENANTS OF VISTA AND SUB.

       6.1    ACCESS AND INVESTIGATION.  During the Pre-Closing Period, VISTA 
and SUB shall, and shall cause their Representatives to: (A) provide GEOSURE 
and GEOSURE's Representatives with reasonable access to VISTA's 
Representatives, personnel and assets and to all existing books, records, and 
other documents and information relating to VISTA; and (B) provide GEOSURE 
and GEOSURE's Representatives with copies of such existing books, records, 
and other documents and information relating to VISTA or SUB, and with such 
additional financial, operating and other data and information regarding 
VISTA, as GEOSURE may reasonably request.

       6.2    NOTIFICATION; UPDATES TO VISTA DISCLOSURE SCHEDULE.

              (a)    During the Pre-Closing Period, VISTA shall promptly 
notify GEOSURE in writing of:

                     (i)    the discovery by VISTA of any event, condition, 
fact or circumstance that occurred or existed on or prior to the date of this 
Agreement and that caused or constitutes an inaccuracy in or breach of any 
representation or warranty made by VISTA or SUB in this Agreement;

                     (ii)   any event, condition, fact or circumstance that 
occurs, arises or exists after the date of this Agreement and that would 
cause or constitute an inaccuracy in or breach of any representation or 
warranty made by VISTA or SUB in this Agreement if (A) such representation or 
warranty had been made as of the time of the occurrence, existence or 
discovery of such event, condition, fact or circumstance, or (B) such event, 
condition, fact or circumstance had occurred, arisen or existed on or prior 
to the date of this Agreement;

                     (iii)  any breach of any covenant or obligation of VISTA 
or SUB; and

                     (iv)   any event, condition, fact or circumstance that 
would make the timely satisfaction of any of the conditions set forth in 
Section 8 or Section 9 impossible or unlikely.

              (b)    If any event, condition, fact or circumstance that is 
required to be disclosed pursuant to Section 6.2(a) requires any change in 
the VISTA Disclosure Schedule, or if any such event, condition, fact or 
circumstance would require such a change assuming the VISTA Disclosure 
Schedule were dated as of the date of the occurrence, existence or discovery 
of such event, condition, fact or circumstance, then VISTA shall promptly 
deliver to GEOSURE an update to the VISTA Disclosure Schedule specifying such 
change.  No such update shall be deemed to supplement or amend the VISTA 
Disclosure Schedule for the purpose of (i) determining the accuracy of any of 
the representations and warranties made by VISTA or SUB in this Agreement, or 
(ii) determining whether any of the conditions set forth in Section 9 has 
been satisfied; provided, however, that if Closing occurs, VISTA's Disclosure 
Schedule shall be deemed to be modified at such time by such update.

                                       26
<PAGE>

7.     ADDITIONAL COVENANTS OF GEOSURE AND VISTA.

       7.1    FILINGS AND CONSENTS.  As promptly as practicable after the 
execution of this Agreement, each party to this Agreement (a) shall make all 
filings (if any) and give all notices (if any) required to be made and given 
by such party in connection with the Acquisition and the other transactions 
contemplated by this Agreement, and (b) shall use all commercially reasonable 
efforts to obtain all Consents (if any) required to be obtained (pursuant to 
any applicable Legal Requirement or Contract, or otherwise) by such party in 
connection with the Acquisition and the other transactions contemplated by 
this Agreement.  GEOSURE shall (upon request) promptly deliver to VISTA a 
copy of each such filing made, each such notice given and each such Consent 
obtained by GEOSURE during the Pre-Closing Period.

       7.2    PUBLIC ANNOUNCEMENTS.  During the Pre-Closing Period, (A) 
neither GEOSURE nor any of the Partners shall (and GEOSURE shall not permit 
any of its Representatives to) issue any press release or make any public 
statement regarding this Agreement or the Acquisition, or regarding any of 
the other transactions contemplated by this Agreement, without VISTA's prior 
written consent, which shall not be unreasonably withheld, and (B) except as 
may be required by law, VISTA will not issue any press release or make any 
public statement regarding this Agreement or the Acquisition, without 
GEOSURE's prior written consent, which shall not be unreasonably withheld.

       7.3    POOLING OF INTERESTS.  During the Pre-Closing Period, no party 
to this Agreement shall take any action that could reasonably be expected to 
have an adverse effect on the ability of VISTA to account for the Acquisition 
as a "pooling of interests."

       7.4    AFFILIATE AGREEMENTS.  Each Partner who is an affiliate of 
GEOSURE shall execute and deliver to VISTA, and GEOSURE shall use all 
commercially reasonable efforts to cause each other Person identified on 
EXHIBIT D-2 (and any other Person that could reasonably be deemed to be an 
"affiliate" of GEOSURE for purposes of the Securities Act), to execute and 
deliver to VISTA, as promptly as practicable after the execution of this 
Agreement, an Affiliate Agreement in the form of EXHIBIT D-1.

       7.5    BEST EFFORTS.  During the Pre-Closing Period, (a) GEOSURE and 
the Partners shall use their best efforts to cause the conditions set forth 
in Section 8 to be satisfied on a timely basis, and (b) VISTA shall use their 
best efforts to cause the conditions set forth in Section 9 to be satisfied 
on a timely basis.

       7.6    SANBORN AGREEMENT.  GEOSURE shall have the right to fulfill its 
obligations, if any, under the Sanborn Agreement.

       7.7    REGULATORY APPROVALS.  In addition to the obligations of the 
parties set forth in the preceding section, GEOSURE and VISTA shall use all 
reasonable efforts to file, as soon as practicable after the date of this 
Agreement, all notices, reports and other documents required to be filed with 
any Governmental Body with respect to the Acquisition and the other 
transactions contemplated by this Agreement, and to submit promptly any 
additional information requested by any such Governmental Body.  Each of 
GEOSURE and VISTA shall (1) give the other party prompt notice of the 
commencement of any Legal Proceeding by or before any Governmental 

                                       27
<PAGE>

Body with respect to the Acquisition or any of the other transactions 
contemplated by this Agreement, (2) keep the other party informed as to the 
status of any Legal Proceeding, and (3) promptly inform the other party of 
any communication to or from any Governmental Body regarding the Acquisition. 
GEOSURE and VISTA will consult and cooperate with one another, and will 
consider in good faith the views of one another, in connection with any 
analysis, appearance, presentation, memorandum, brief, argument, opinion or 
proposal made or submitted in connection with any Legal Proceeding or any 
federal or state antitrust or fair trade law.  In addition, except as may be 
prohibited by any Governmental Body or by any Legal Requirement, in 
connection with any Legal Proceeding under or relating to any federal or 
state antitrust or fair trade law or any other similar Legal Proceeding, each 
of GEOSURE and VISTA agrees to permit authorized Representatives of the other 
party to be present at each meeting or conference relating to any such Legal 
Proceeding and to have access to and be consulted in connection with any 
document, opinion or proposal made or submitted to any Governmental Body in 
connection with any such Legal Proceeding.

       7.8    REGISTRATION RIGHTS. 

              (a)    On or before 10 days following the filing by VISTA of 
its Annual Report on Form 10-KSB for the fiscal year ended December 31, 1998, 
VISTA will file a registration statement under the Securities Act covering 
the registration for resale by the Partners or their distributees in 
accordance with a plan of distribution reasonably satisfactory to them of all 
of the Exchange Shares then outstanding (except for any Exchange Shares for 
Partners who do not return a Selling Stockholder Questionnaire by March 15, 
1999).  The registration statement will be on Form S-3 if VISTA then 
qualifies for such Form, or such other form as VISTA may then be eligible to 
use.  As used herein, the term "Registrable Securities" shall mean the 
Exchange Shares (including that portion of the Exchange Shares held in the 
escrow pursuant to Section 11.5) included in the registration statement.

              (b)    Notwithstanding the foregoing, if the Company shall 
furnish to the Partners a certificate signed by the President of the Company 
stating that in the good faith judgment of the Board of Directors of the 
Company, it would be seriously detrimental to the Company and its 
stockholders for such registration statement to be filed and it is therefore 
essential to defer the filing of such registration statement, the Company 
shall have the right to defer such filing for a period of not more than 20 
days.

              (c)    In connection with any registration pursuant to this 
Section 7.8, Vista will:

                     (i)    prepare and file with the Commission the 
requisite registration statement to effect such registration 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 and to comply with the provisions of the Securities Act 
with respect to the disposition of all securities covered by such 
registration statement until the earlier of two years after the effective 
date of the registration statement, such time as all remaining Registrable 
Securities could be sold in any 3 month period without 

                                       28
<PAGE>

registration,  or such time as all of such securities have been disposed of 
in accordance with the intended methods of disposition by the Holders thereof 
or their distributees set forth in such registration statement;

                     (iii)  furnish to each Partner holding Registrable 
Securities covered by such registration statement such number of conformed 
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 contained in such registration statement (including 
each preliminary prospectus and any summary prospectus) and any other 
prospectus filed under Rule 424 under the Securities Act, in conformity with 
the requirements of the Securities Act, and such other documents, as such 
Partner may reasonably request;

                     (iv)   use its best efforts to register or qualify all 
Registrable Securities and other securities covered by such registration 
statement under such other securities or blue sky laws of such jurisdictions 
in the United States as each Partner holding such securities shall reasonably 
request, to keep such registration or qualification in effect for so long as 
such registration statement remains in effect, and take any other action 
which may be reasonably necessary or advisable to enable such Partner to 
consummate the disposition in such jurisdictions of the securities owned by 
such Partner;

                     (v)    use its best efforts to cause all Registrable 
Securities to be registered with or approved by such other governmental 
agencies or authorities as may be necessary to enable the Partner(s) holding 
such securities to consummate the disposition of such Registrable Securities;

                     (vi)   promptly notify each Partner holding Registrable 
Securities at any time when a prospectus relating thereto is required to be 
delivered under the Securities Act, 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 under 
which they were made, and Partner promptly prepare and furnish to such 
Partner 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 securities, 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 under which they were made;

                     (vii)  otherwise use its best efforts to comply with all 
applicable rules and regulations of the Commission, and make available to its 
security holders, as soon as reasonably practicable, but not more than 
sixteen months after effectiveness, an earnings statement covering the period 
of at least twelve months, beginning with the first full calendar month after 
the effective date of such registration statement, which earnings statement 
shall satisfy the provisions of Section 11(a) of the Securities Act; 

                     (viii) use its best efforts to list all VISTA Common 
Stock covered by such registration statement on any securities exchange or 
the Nasdaq Stock Market on which any of the VISTA Common Stock is then 
listed; and

                                       29
<PAGE>

                     (ix)   provide each Partner holding Registrable 
Securities with an opinion of counsel, dated as of the effective date of the 
Registration Statement, that the Registration Statement has been declared 
effective by the Commission and complies as to form with the requirement of 
the Securities Act.

                     Each Partner holding Registrable Securities agrees that 
upon receipt of any notice from VISTA of the happening of any event of the 
kind described in subsection (vi) of this Section 7.8(c), such Partner will 
forthwith discontinue such Partner's disposition of Registrable Securities 
pursuant to the registration statement relating to such Registrable 
Securities until such Partner's receipt of the copies of the supplemented or 
amended prospectus and, if so directed by VISTA, will deliver to VISTA (at 
VISTA's expense) all copies, other than permanent file copies, then in such 
Partner's possession of the prospectus relating to such Registrable 
Securities current at the time of receipt of such notice.

              (d)    VISTA will indemnify each Partner, each of its officers 
and directors and partners, and each person controlling such Partner within 
the meaning of Section 15 of the Securities Act against all expenses 
(including but not limited to reasonable attorney's fees), claims, losses, 
damages or liabilities (or actions in respect thereof), including any of the 
foregoing incurred in settlement of any litigation, commenced or threatened, 
arising out of or based on any untrue statement (or alleged untrue statement) 
of a material fact contained in any registration statement, prospectus, 
preliminary prospectus, offering circular or other document, or any amendment 
or supplement thereto, incident to any registration, qualification or 
compliance effected pursuant to this Section 7.8, or based on any omission 
(or alleged omission) to state therein a material fact required to be stated 
therein or necessary to make the statements therein, in light of the 
circumstances in which they were made, not misleading, or any violation or 
any alleged violation in each instance by VISTA of any rule or regulation 
promulgated under the Securities Act or the Exchange Act in connection with 
any such registration, qualification or compliance, and VISTA will reimburse 
each such Partner, each of its officers and directors, and each person 
controlling such Partner, for any legal and any other expenses reasonably 
incurred in connection with investigating, preparing or defending any such 
claim, loss, damage, liability or action, as such expenses are incurred, 
provided that VISTA will not be liable in any such case to the extent that 
any such claim, loss, damage, liability or expense arises out of or is based 
on any untrue statement or omission or alleged untrue statement or omission, 
made in reliance upon and in conformity with written information furnished to 
VISTA by such Partner or controlling person specifically for use therein.

              (e)    Each Partner (an "Indemnifying Partner") will, if 
Exchange Shares held by such Indemnifying Partner are included in the 
securities as to which such registration is being effected, indemnify VISTA, 
each of its directors and officers, each person who controls VISTA within the 
meaning of Section 15 of the Securities Act, and each other Partner with 
securities included in such registration, each of its officers and directors 
and each person controlling such other Partner within the meaning of Section 
15 of the Securities Act, against all expenses (including but not limited to 
reasonable attorney's fees), claims, losses, damages and liabilities (or 
actions in respect thereof) arising out of or based on any untrue statement 
(or alleged untrue statement) of a material fact contained in any such 
registration statement, prospectus, offering circular or other document, or 
any omission (or alleged omission) to state therein a material fact 

                                       30
<PAGE>

required to be stated therein or necessary to make the statements therein, in 
light of the circumstances in which they were made, not misleading, and will 
reimburse VISTA, such other Partners, directors, officers, persons or control 
persons for any legal or any other expenses reasonably incurred in connection 
with investigating or defending any such claim, loss, damage, liability or 
action, as such expenses are incurred, in each case to the extent, but only 
to the extent, that such untrue statement (or alleged untrue statement) or 
omission (or alleged omission) is made in such registration statement, 
prospectus, offering circular or other document in reliance upon and in 
conformity with written information furnished to VISTA by the Indemnifying 
Partner specifically for use therein.

              (f)    Each party entitled to indemnification under Section 
7.8(d) or 7.8(e) (the "Indemnified Party") shall give notice to the party 
required to provide indemnification (the "Indemnifying Party") promptly after 
such Indemnified Party has actual knowledge of any claim as to which 
indemnity may be sought, and shall permit the Indemnifying Party to assume 
the defense of any such claim or any litigation resulting therefrom, provided 
that counsel for the Indemnifying Party, who shall conduct the defense of 
such claim or litigation, shall be approved by the Indemnified Party (whose 
approval shall not unreasonably be withheld), and the Indemnified Party may 
participate in such defense at such party's expense; PROVIDED, HOWEVER, that 
an Indemnified Party (together with all other Indemnified Parties which may 
be represented without conflict by one counsel) shall have the right to 
retain one separate counsel, with the fees and expenses to be paid by the 
Indemnifying Party, if representation of such Indemnified Party by the 
counsel retained by the Indemnifying Party would be inappropriate due to 
differing or potentially differing interests between such Indemnified Party 
and any other party represented by such counsel in such proceeding.  The 
failure of any Indemnified Party to give notice as provided herein shall not 
relieve the Indemnifying Party of its obligations under Section 7.9(d) or 
7.9(e) unless the failure to give such notice is materially prejudicial to an 
Indemnifying Party's ability to defend such action.  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.

              (g)    VISTA shall pay all of the out-of-pocket expenses (other 
than underwriting discounts and sales commissions, if any, allocable to any 
Partner's Registrable Securities and, except as contemplated by Section 
7.9(f), the fees and expenses of any counsel to the Partners) incurred in 
connection with any registration of Registrable Securities pursuant to this 
Section 7.8, including, without limitation, all registration and filing fees, 
printing expenses, transfer agents' and registrars' fees, and the reasonable 
fees and disbursements of VISTA's outside counsel and independent accountants.

              (h)    If for any reason the indemnification provided for in 
subsection 7.8(d) or 7.8(e) is unavailable to an Indemnified Party as 
contemplated therein, then the Indemnifying Party, in lieu of 
indemnification, shall contribute to the amount paid or payable by the 
Indemnified Party as a result of such loss, claim, damage, expense or 
liability (or action in respect hereof) in such proportion as is appropriate 
to reflect not only the relative benefits received by the Indemnified Party 
and the Indemnifying Party, but also the relative fault of the 

                                       31
<PAGE>

Indemnified Party and the Indemnifying Party, as well as any other relevant 
equitable considerations, provided that no holder of Registrable Securities 
shall be required to contribute in an amount greater than the difference 
between the net proceeds received by such holder with respect to the sale of 
any Registrable Securities and all amounts already contributed by such 
Partner with respect to such claims, including amounts paid for any legal or 
other fees or expenses incurred by such Partner.  No person guilty of a 
fraudulent misrepresentation (within the meaning of Section 11(f) of the 
Securities Act) shall be entitled to contribution from any person who was not 
guilty of any such fraudulent misrepresentation.  The relative fault of such 
Indemnifying Party and Indemnified Party shall be determined by reference to, 
among other things, whether any action in question, including any untrue or 
alleged untrue statement of a material fact or omission or alleged omission 
to state a material fact, has been made by, or relates to information 
supplied by, such Indemnifying Party or Indemnified Party, and the parties' 
relative intent, knowledge, access to information and opportunity to correct 
or prevent such action.

              (i)    With a view to making available to the Partners the 
benefits of Rule 144 promulgated under the Securities Act (or any other rule 
that may permit the Partners to sell Exchange Securities without registration 
or pursuant to a registration on Form S-3), VISTA will file with the 
Commission in a timely fashion all reports required under the Exchange Act.

       7.9    FIRPTA MATTERS.  At the Closing, GEOSURE shall deliver to VISTA 
a statement (in such form as may be reasonably requested by counsel to VISTA) 
conforming to the requirements of Section 1.1445-11T(d)(2)(i) of the United 
States Treasury Regulations, certifying that fifty percent (50%) or more of 
the value of the gross assets of GEOSURE does not consist of U.S. real 
property interests within the meaning of Code section 897.

       7.10   TREATMENT OF EMPLOYEE PLANS AND BENEFITS.  Except as otherwise 
agreed to by VISTA and GEOSURE, VISTA shall ensure that upon the Closing, the 
benefit plans and benefit arrangements of employees of GEOSURE will remain 
unchanged.  Following the Closing, benefits will be reviewed in consonance 
with VISTA benefit plans and arrangements, applicable law and marketplace 
factors.

       7.11   EMPLOYEE INDEMNIFICATION.  VISTA and GEOSURE agree to provide 
indemnification in favor of any employee of GEOSURE and its Subsidiaries (the 
"Indemnified Parties"), as currently provided in their respective charter 
documents or in an agreement between an Indemnified Party and GEOSURE or one 
of its Subsidiaries set forth in Part 7.11 of GEOSURE Disclosure Schedule, 
and rights to indemnification shall survive the Acquisition and shall 
continue in full force and effect for a period of two years after the 
Closing; provided that in the event any claim or claims are asserted or made 
within such two-year period, all rights to indemnification in respect to any 
such claim shall continue until final disposition of such claim; provided, 
however, that no Partner shall be eligible to assert a claim for 
indemnification from GEOSURE or any of its Subsidiaries in a matter subject 
to Section 11.

       7.12   TAX RETURNS AND FINANCIAL STATEMENTS.  VISTA shall arrange for 
its accountants to (i) audit the financial statements of GEOSURE as of and 
for the year ended December 31, 1998, and (ii) prepare, following the Closing 
Date, tax returns for GEOSURE for the year ended 

                                       32
<PAGE>

December 31, 1998 and for the partial year from January 1, 1999 until the 
Closing Date.  The parties acknowledge that the purchase of the partnership 
interests of GEOSURE will be reported as taxable transactions.

       7.13   CAPITAL AVAILABILITY AGREEMENT.  Following the Closing Date, 
VISTA shall indemnify the Partners, Bruce Llewellyn and Burton Rubin from any 
liabilities they may incur as a result of claims made by State Street Bank 
and Trust Company for additional amounts they may be required to pay pursuant 
to the Capital Availability Agreement with State Street Bank and Trust 
Company following the Closing Date.

8.     CONDITIONS PRECEDENT TO OBLIGATIONS OF VISTA AND SUB.

       The obligations of VISTA and SUB to effect the Acquisition and 
otherwise consummate the transactions contemplated by this Agreement are 
subject to the satisfaction, at or prior to the Closing, of each of the 
following conditions:

       8.1    ACCURACY OF REPRESENTATIONS.  Each of the representations and 
warranties made by GEOSURE and the Partners in this Agreement and in each of 
the other agreements and instruments delivered to VISTA in connection with 
the transactions contemplated by this Agreement shall have been accurate in 
all material respects as of the date of this Agreement (without giving double 
effect to any "Material Adverse Effect" or other materiality qualifications, 
or any similar qualifications, contained or incorporated directly or 
indirectly in such representations and warranties), and shall be accurate in 
all material respects as of the Closing Date as if made at the Closing Date 
(without giving double effect to any update to GEOSURE Disclosure Schedule 
not consented to in writing by VISTA, and without giving effect to any 
"Material Adverse Effect" or other materiality qualifications, or any similar 
qualifications, contained or incorporated directly or indirectly in such 
representations and warranties).

       8.2    PERFORMANCE OF COVENANTS.  All of the covenants and obligations 
that GEOSURE and the Partners are required to comply with or to perform at or 
prior to the Closing shall have been complied with and performed in all 
respects at or prior to Closing.

       8.3    NO DISTRIBUTIONS.  There will have not been any distributions 
to the Partners since September 30, 1998.

       8.4    CONSENTS.  All material Consents required to be obtained in 
connection with the Acquisition and the other transactions contemplated by 
this Agreement (including the Consents identified in Part 2.22 of GEOSURE 
Disclosure Schedule and the consent, on terms reasonably acceptable to VISTA, 
of State Street Bank & Trust Company, GEOSURE's bank) shall have been 
obtained and shall be in full force and effect.  

       8.5    AGREEMENTS AND DOCUMENTS.  VISTA shall have received the 
following agreements and documents, each of which shall be in full force and 
effect:  

                                       33
<PAGE>

              (a)    Affiliate's Agreements in the form of EXHIBIT D-1 
executed by any Person who could reasonably be deemed to be an "affiliate" of 
GEOSURE for purposes of the Securities Act;

              (b)    an agreement terminating GEOSURE's obligations under its 
contract with DP pursuant to the terms thereof, which would not involve a 
cost or charge to GEOSURE in excess of the $200,000 currently specified;

              (c)    to the extent reasonably requested by VISTA, 
confidential invention and assignment agreements, reasonably satisfactory in 
form and content to VISTA, executed by all employees of GEOSURE and by all 
consultants and independent contractors to GEOSURE who have not already 
signed such agreements (including the individuals identified in Part 2.9(f) 
of GEOSURE Disclosure Schedule);

              (d)    a legal opinion of Rubin Baum Levin Constant & Friedman, 
dated as of the Closing Date, covering the matters set forth in EXHIBIT E;

              (e)    a letter from Leslie Sufrin and Company, P.C., dated as 
of the Closing Date, confirming that no transaction entered into by GEOSURE, 
and no other fact or circumstance relating to GEOSURE, will prevent VISTA 
from accounting for the Acquisition as a "pooling of interests" in accordance 
with generally accepted principles, Accounting Principles Board Opinion No. 
16;

              (f)    a certificate executed by GEOSURE's General Partners 
(solely in their capacity as such and not in their capacity as a Partner) and 
containing the representation and warranty that each of the representations 
and warranties set forth in Section 2 is accurate in all respects as of the 
Closing Date as if made on the Closing Date and that the conditions set forth 
in Sections 8.1, 8.2, 8.3, 8.4, 8.7 and 8.8 have been duly satisfied (the 
"GEOSURE Closing Certificate"); and 

              (g)    The Escrow Agreement in substantially the form attached 
hereto as EXHIBIT G, executed by or on behalf of the Partners and the Escrow 
Agent (as defined therein).

       8.6    COMPLIANCE WITH THE SECURITIES ACT.  All applicable 
requirements of the Securities Act and state securities laws shall have been 
satisfied.

       8.7    NO RESTRAINTS.  No temporary restraining order, preliminary or 
permanent injunction or other order preventing the consummation of the 
Acquisition shall have been issued by any court of competent jurisdiction and 
remain in effect, and there shall not be any Legal Requirement enacted or 
deemed applicable to the Acquisition that makes consummation of the 
Acquisition illegal.

       8.8    NO LEGAL PROCEEDINGS.  No Person shall have commenced or 
threatened to commence any Legal Proceeding challenging or seeking the 
recovery of a material amount of damages in connection with the Acquisition 
or seeking to prohibit or limit the exercise by VISTA of any material right 
pertaining to its ownership of GEOSURE or its assets.

                                       34
<PAGE>

       8.9    GEOSURE'S KEY EMPLOYEES.  VISTA shall be reasonably satisfied 
that GEOSURE has used its best efforts during the Pre-Closing Period to 
ensure that certain key GEOSURE employees (as identified by VISTA) will 
continue their employment with the VISTA or the Acquired Entities.

       8.10   DUE DILIGENCE.VISTA shall be satisfied with the results of its 
inspection and review of GEOSURE and its business.

9.     CONDITIONS PRECEDENT TO OBLIGATIONS OF GEOSURE AND THE PARTNERS.

       The obligations of GEOSURE and the Partners to effect the Acquisition 
and otherwise consummate the transactions contemplated by this Agreement are 
subject to the satisfaction, at or prior to the Closing, of the following 
conditions:

       9.1    ACCURACY OF REPRESENTATIONS.  Each of the representations and 
warranties made by VISTA and SUB in this Agreement and in each of the other 
agreements and instruments delivered to GEOSURE and the Partners in 
connection herewith, shall have been accurate in all material respects as of 
the date of this Agreement (without giving effect to any "Materially Adverse 
Effect" or other materiality qualifications, or any similar qualifications, 
contained or incorporated directly or indirectly in such representations and 
warranties), and shall be accurate in all material respects as of the Closing 
Date as if made at the Closing Date (without giving effect to any "Material 
Adverse Effect" or other materiality qualifications, or any similar 
qualifications, contained in such representations and warranties).

       9.2    PERFORMANCE OF COVENANTS.  All of the covenants and obligations 
that VISTA or SUB are required to comply with or to perform at or prior to 
the Closing shall have been complied with and performed in all respects.

       9.3    DOCUMENTS.  GEOSURE shall have received the following documents:

              (a)    a legal opinion of Gray Cary Ware and Freidenrich LLP, 
dated as of the Closing Date, covering the matters set forth in EXHIBIT F; 

              (b)    a certificate executed by the Chief Executive Officer of 
each of VISTA and SUB and containing the representation and warranty that 
each of the representations and warranties set forth in Section 4 is accurate 
in all respects as of the Closing Date as if made on the Closing Date and 
that the conditions set forth in Sections 9.1 and 9.2 have been duly 
satisfied (the "VISTA Closing Certificate"); and

              (c)    The Escrow Agreement, executed by VISTA and the Escrow 
Agent.

       9.4    NO RESTRAINTS.  No temporary restraining order, preliminary or 
permanent injunction or other order preventing the consummation of the 
Acquisition shall have been issued by any court of competent jurisdiction and 
remain in effect, and there shall not be any Legal Requirement enacted or 
deemed applicable to the Merger that makes consummation of the Merger illegal.

                                       35

<PAGE>

       9.5    COMPLIANCE WITH THE SECURITIES ACT.  All applicable 
requirements of the Securities Act and state securities laws shall have been 
satisfied.

       9.6    NO LEGAL PROCEEDINGS.  No Person shall have commenced or 
threatened to commence any Legal Proceeding challenging or seeking the 
recovery of a material amount of damages in connection with the Acquisition 
or seeking to prohibit or limit the exercise by VISTA of any material right 
pertaining to its ownership of GEOSURE or its assets.

10.    TERMINATION

       10.1   TERMINATION EVENTS.  This Agreement may be terminated prior to 
the Closing without either party (except as provided in Section 10.1(e)) 
incurring any termination fee:

              (a)    by VISTA, if VISTA reasonably determines that the timely 
satisfaction of any condition set forth in Section 8 has become impossible 
(other than as a result of any failure on the part of VISTA to comply with or 
perform any covenant or obligation of VISTA set forth in this Agreement);

              (b)    by GEOSURE, if GEOSURE reasonably determines that the 
timely satisfaction of any condition set forth in Section 9 has become 
impossible (other than as a result of any failure on the part of GEOSURE or 
any of the Partners to comply with or perform any covenant or obligation set 
forth in this Agreement or in any other agreement or instrument delivered to 
VISTA);

              (c)    by VISTA, if the Closing has not taken place on or 
before March 31, 1999 (other than as a result of any failure on the part of 
VISTA to comply with or perform any covenant or obligation of VISTA set forth 
in this Agreement);

              (d)    by GEOSURE, if the Closing has not taken place on or 
before March 31, 1999 (other than as a result of the failure on the part of 
GEOSURE or any of the Partners to comply with or perform any covenant or 
obligation set forth in this Agreement or in any other agreement or 
instrument delivered to VISTA);

              (e)    by GEOSURE (at any time prior to Partner approval of 
this Agreement, the Acquisition and the transactions contemplated hereby) if, 
pursuant to and in compliance with Section 5.4, GEOSURE and its general 
partners conclude in good faith that GEOSURE must accept an unsolicited bona 
fide written proposed Acquisition Transaction which could reasonably be 
expected to result in a transaction that is more favorable to the Partners 
than the Acquisition (any such more favorable proposed Acquisition 
Transaction being referred to in this Agreement as a "Superior Proposal"); 
provided, however, that if this Agreement is terminated pursuant to this 
Section 10.1(e), GEOSURE shall pay to VISTA a nonrefundable fee of $500,000 
in cash upon GEOSURE's (or its General Partners') election to accept such 
Superior Proposal.  In reaching such conclusion, the general partners of 
GEOSURE shall consult with outside legal counsel (and other advisors as 
appropriate);

              (f)    by the mutual consent of VISTA and GEOSURE; or

                                       36
<PAGE>

              (g)    by VISTA, as provided in Section 10.3.

       10.2   TERMINATION PROCEDURES.  If VISTA wishes to terminate this 
Agreement pursuant to Section 10.1(a), Section 10.1(c) or Section 10.1(g), 
VISTA shall deliver to GEOSURE prompt written notice stating that VISTA is 
terminating this Agreement and setting forth a brief description of the basis 
on which VISTA is terminating this Agreement.  If GEOSURE wishes to terminate 
this Agreement pursuant to Section 10.1(b), Section 10.1(d) or Section 
10.1(e), GEOSURE shall deliver to VISTA prompt written notice stating that 
GEOSURE is terminating this Agreement and setting forth a brief description 
of the basis on which GEOSURE is terminating this Agreement.

       10.3   EFFECT OF TERMINATION.  If this Agreement is terminated 
pursuant to Section 10.1, all further obligations of the parties under this 
Agreement shall terminate; provided, however, that (i) neither GEOSURE nor 
VISTA shall be relieved of any obligation or liability arising from any prior 
breach by such party of any provision of this Agreement; (ii) the parties 
shall, in all events, remain bound by and continue to be subject to the 
provisions set forth in Section 12; and (iii) GEOSURE shall, in all events, 
remain bound by and continue to be subject to Section 7.3.

11.    SURVIVAL OF REPRESENTATIONS; INDEMNIFICATION.

       11.1   SURVIVAL OF REPRESENTATIONS.

              (a)    Subject to the indemnification limitations set forth in 
Section 11.2, the representations and warranties made by GEOSURE, the 
Partners and VISTA in Sections 2, 3 and 4 shall survive the Closing and shall 
expire on the first anniversary of the Closing Date (the "Claim Deadline") 
except as follows: (i) representations and warranties contained in Section 
7.5 shall survive the Closing Date indefinitely; (ii) representations and 
warranties contained in Section 2.14 shall survive for the period of the 
applicable statute of limitations plus any extensions or waivers granted or 
imposed with respect thereto; (iii) in the event of fraud, the applicable 
representations and warranties shall survive indefinitely; and (iv) if, at 
any time prior to the first anniversary of the Closing Date, any Indemnitee 
(acting in good faith) delivers to the Escrow Agent (in the case of a claim 
against the Partners) or to VISTA (in the case of a claim by a Partner) a 
written notice asserting a claim for recovery under Section 11.2, then the 
claim asserted in such notice shall survive the first anniversary of the 
Closing until such time as such claim is fully and finally resolved.  

              (b)    The representations, warranties, covenants and 
obligations of the parties hereto, and (except as provided herein) the rights 
and remedies that may be exercised pursuant hereto, shall not be limited or 
otherwise affected by or as a result of any information furnished to or any 
investigation made by or knowledge of (except as provided herein, in GEOSURE 
Disclosure Schedule or the VISTA Disclosure Schedule), any of the parties or 
any of their Representatives.

              (c)    For purposes of this Agreement, each statement or other 
item of information set forth in the parties' disclosure schedules or in any 
update to the parties' disclosure schedules shall be deemed to be a 
representation and warranty made by that party in this Agreement.

                                       37
<PAGE>

       11.2   INDEMNIFICATION.

              (a)    From and after the Closing Date, VISTA shall be held 
harmless and indemnified by the Partners from and against, and shall be 
compensated and reimbursed by the Partners for, any Damages which are 
directly or indirectly suffered or incurred by VISTA or to which VISTA may 
otherwise become subject (regardless of whether or not such Damages relate to 
any third-party claim) and which arise from or as a result of, or are 
directly or indirectly connected with: (i) any inaccuracy in or breach of any 
representation or warranty of GEOSURE or the Partners set forth in Sections 2 
and 3; and (ii) any Legal Proceeding relating to any inaccuracy or breach of 
the type referred to in clause "(i)" above (including any Legal Proceeding 
commenced by VISTA for the purpose of enforcing any of its rights under this 
Section 11); PROVIDED, HOWEVER, that (y) except as set forth in the following 
clause, VISTA shall not be entitled to any indemnification hereunder until 
the total Damages as to which it would otherwise be entitled to for 
indemnification hereunder exceed $50,000, and (z) VISTA shall be entitled to 
indemnification for any Damages resulting from a breach of the 
representations and warranties set forth in the final sentence of Section 
2.11.  The parties acknowledge and agree that, if GEOSURE or SUB suffers, 
incurs or otherwise becomes subject to any Damages as a result of or in 
connection with any inaccuracy in or breach of any representation, warranty, 
covenant or obligation of GEOSURE or the Partners set forth in Sections 2 or 
3, then VISTA shall also be deemed, by virtue of its ownership of GEOSURE and 
SUB (and their assets upon dissolution), to have incurred Damages as a result 
of and in connection with such inaccuracy or breach.  The liability of each 
Partner under this Agreement shall be limited to the number of Exchange 
Shares actually received by such Person pursuant to Section 1.4.

              (b)    In addition to the indemnification provided pursuant to 
Section 7.13, from and after the Closing Date, the Partners shall be held 
harmless and indemnified by VISTA from and against, and shall be compensated 
and reimbursed by VISTA for any Damages which are directly or indirectly 
suffered or incurred by the Partners or to which Partners may otherwise 
become subject (regardless of whether or not such Damages relate to any 
third-party claim) and which arise from or as a result of, or are directly or 
indirectly connected with: (i) any inaccuracy in or breach of any 
representation or warranty of VISTA or SUB set forth in Section 4; (ii) any 
Legal Proceeding relating to any inaccuracy or breach of the type referred to 
in clause "(i)" above (including any legal proceeding commenced by a Partner 
for purpose of enforcing any of its rights under this Section 11); PROVIDED, 
HOWEVER, that the Partners shall not be entitled to any indemnification 
hereunder until the total Damages as to which they would  otherwise be 
entitled to for indemnification hereunder exceed $50,000.  

       11.3   INTEREST.  Any Indemnitee provided indemnification pursuant to 
this Section 11 with respect to any Damages shall also be entitled to receive 
interest on the amount of such Damages (for the period commencing as of the 
date of a claim for recovery by such Indemnitee and ending on the date on 
which the liability to such Indemnitee is fully satisfied pursuant hereto) at 
a floating rate equal to the rate of interest publicly announced by Bank of 
America, N.T. & S.A.  from time to time as its prime, base or reference rate.

       11.4   DEFENSE OF THIRD PARTY CLAIMS.  In the event of the assertion 
or commencement by any Person of any claim or Legal Proceeding (whether 
against GEOSURE or against VISTA) 

                                       38
<PAGE>

with respect to which VISTA may be entitled to payment pursuant to this 
Section 11 and where the amount as to which VISTA may be entitled to such 
payment is reasonably expected to be $100,000 or less, VISTA shall have the 
right, at its election, to proceed with the defense of such claim or Legal 
Proceeding on its own.  If VISTA so proceeds with the defense of any such 
claim or Legal Proceeding, then, subject to the limitations of Section 
11.2(b):  (a)  all reasonable expenses relating to the defense of such claim 
or Legal Proceeding shall be borne and paid exclusively by the Partners;  
(b)  the parties shall use reasonable efforts to make available to VISTA any 
documents and materials in their possession or control that may be necessary 
to the defense of such claim or Legal Proceeding; and  (c)  VISTA shall not 
settle, adjust or compromise such claim or Legal Proceeding without the 
consent of a majority in interest of the Partners, which consents shall not 
be unreasonably withheld.  Notwithstanding the provisions of this Section 
11.4 to the contrary, in the event the claim or Legal Proceeding is 
reasonably expected to result in a payment in excess of $100,000, then the 
parties will use their good faith efforts to enter into a cooperative defense 
agreement addressing the relevant issues, including control, on the basis of 
the potential exposure of the parties, the importance of the matter to the 
ongoing business of GEOSURE (or its successors), the relative knowledge of 
the parties, and any perceived difference in the ability of the parties to 
resolve the matter efficiently.

       11.5   INDEMNITY ESCROW FUND.  At Closing, VISTA shall deliver a stock 
certificate representing ten percent (10%) of the Exchange Shares to Norwest 
Bank, N.A. as escrow agent (the "Indemnity Escrow Agent"), such deposit to 
constitute the "Indemnity Escrow Fund" which shall be governed by the terms 
set forth herein and substantially in the form Indemnity Escrow Agreement 
attached hereto as EXHIBIT G (the "Indemnity Escrow Agreement").  The 
Indemnity Escrow fund will serve as collateral for the indemnification 
obligations of and the payment of Damages by the Partners as set forth in 
this Section 11.  Withdrawal of such shares of stock shall be subject to 
restrictions consistent with this Section 11 and the terms of the Indemnity 
Escrow Agreement.  All such shares of stock that are not then subject to 
claims regarding Damages shall be released to the GEOSURE Partners in 
proportion to the distribution made at the Closing one year after the Closing 
Date; provided, however, that any such shares of stock which are subject to 
unresolved claims upon the first anniversary of the Closing shall be released 
to the Partners only upon the resolution of such claims. Subject to the 
limitations of Section 11.3, this Section 11.5 is not intended to establish a 
ceiling or maximum amount that the Partners shall indemnify VISTA pursuant to 
this Section 11.

12.    MISCELLANEOUS PROVISIONS.

       12.1   FURTHER ASSURANCES.  Each party hereto shall execute and cause 
to be delivered to each other party hereto such instruments and other 
documents, and shall take such other actions, as such other party may 
reasonably request (prior to, at or after the Closing) for the purpose of 
carrying out or evidencing any of the transactions contemplated by this 
Agreement.

       12.2   FEES AND EXPENSES.  Each party to this Agreement shall bear and 
pay all fees, costs and expenses (including legal fees and accounting fees) 
that have been incurred or that are incurred by such party in connection with 
the transactions contemplated by this Agreement, including all fees, costs 
and expenses incurred by such party in connection with or by virtue of (a) 
the investigation and review conducted by VISTA and its Representatives with 
respect to 

                                       39

<PAGE>

GEOSURE's business (and the furnishing of information to VISTA and its 
Representatives in connection with such investigation and review), (b) the 
negotiation, preparation and review of this Agreement (including the 
respective Disclosure Schedules) and all agreements, certificates, opinions 
and other instruments and documents delivered or to be delivered in 
connection with the transactions contemplated by this Agreement, (c) the 
preparation and submission of any filing or notice required to be made or 
given in connection with any of the transactions contemplated by this 
Agreement, and the obtaining of any Consent required to be obtained in 
connection with any of such transactions, and (d) the consummation of the 
Acquisition.  Following the Acquisition, VISTA will cause GEOSURE to pay the 
fees and expenses of GEOSURE's counsel and accountants with respect to this 
transaction following receipt of appropriately detailed invoices and in an 
aggregate amount up to $85,000.

       12.3   ATTORNEYS' FEES.  If any action or proceeding relating to this 
Agreement or the enforcement of any provision of this Agreement is brought 
against any party hereto, the prevailing party shall be entitled to recover 
reasonable attorneys' fees, costs and disbursements (in addition to any other 
relief to which the prevailing party may be entitled).

       12.4   NOTICES.  Any notice or other communication required or 
permitted to be delivered to any party under this Agreement shall be in 
writing and shall be deemed properly delivered, given and received when 
delivered (by hand, by registered mail return receipt requested, postage and 
fees prepaid, by courier or express delivery service or by facsimile with 
electronic confirmation of receipt) to the address or facsimile telephone 
number set forth beneath the name of such party below (or to such other 
address or facsimile telephone number as such party shall have specified in a 
written notice given to the other parties hereto):

       if to VISTA or SUB:

       VISTA Information Solutions, Inc.
       Attn.:  Chief Financial Officer
       5000 Shoreham Place, #300
       San Diego, CA 92122
       Telephone: (619) 450-6100
       Facsimile: (619) 450-6185

       with a copy to:

       Gray Cary Ware & Freidenrich LLP
       Attn.:  Douglas J. Rein 
       4365 Executive Drive, Suite 1600
       San Diego, California 92121-2189
       Telephone: (619) 677-1400
       Facsimile: (619) 677-1477

       if to GEOSURE:

       Burton R. Rubin
       c/o   Rubin Baum Levin Constant & Friedman

                                       40
<PAGE>

       30 Rockefeller Plaza
       New York, NY 10012
       Telephone: (212) 698-7700
       Facsimile: (212) 698-7825

       with a copy to:

       Rubin Baum Levin Constant & Friedman
       Attn: Robert B. Zimmerman
       30 Rockefeller Plaza
       New York, NY 10012
       Telephone: (212) 698-7700
       Facsimile: (212) 698-7825

if to the Partners (respectively):

       At the address set forth on Exhibit A. 

       12.5   CONFIDENTIALITY.  Without limiting the generality of anything 
contained in Section 7.3, on and at all times after the Closing Date, each 
Partner shall keep confidential, and shall not use or disclose to any other 
Person, any nonpublic document or other nonpublic information in such 
Partner's possession that relates to the business of GEOSURE or VISTA; 
provided, however, the Confidentiality Agreement dated May 21, 1998 between 
Bachow and Associates, Inc. and GEOSURE shall remain in full force and 
effect, unaffected by the execution of this Agreement or by the Acquisition.  
By execution of this Agreement, VISTA agrees to be bound by the terms of such 
Confidentiality Agreement.

       12.6   TIME OF THE ESSENCE.  Time is of the essence of this Agreement.

       12.7   HEADINGS.  The underlined headings contained in this Agreement 
are for convenience of reference only, shall not be deemed to be a part of 
this Agreement and shall not be referred to in connection with the 
construction or interpretation of this Agreement.

       12.8   COUNTERPARTS.  This Agreement may be executed in several 
counterparts, each of which shall constitute an original and all of which, 
when taken together, shall constitute one agreement.  Any such counterpart 
may be executed and delivered by telecopier or other facsimile transmission 
all with the same force and effect as if such counterpart had been manually 
executed and delivered as an original.

       12.9   GOVERNING LAW.  This Agreement shall be construed in accordance 
with, and governed in all respects by, the internal laws of the State of 
Delaware (without giving effect to principles of conflicts of laws), except 
to the extent the New York Revised Limited Partnership Act governs.

       12.10  SUCCESSORS AND ASSIGNS.  This Agreement shall be binding upon: 
GEOSURE and its successors and assigns (if any); the Partners and DP and 
their respective personal representatives, executors, administrators, 
estates, heirs, successors and assigns (if any); and 

                                       41
<PAGE>

VISTA and its successors and assigns (if any).  This Agreement shall inure to 
the benefit of: GEOSURE; the Partners and DP; VISTA; the other Indemnitees 
(subject to Section 11.2); and the respective successors and assigns (if any) 
of the foregoing.  Neither VISTA nor SUB may assign any or all of their 
rights under this Agreement to any Entity, in whole or in part, without 
obtaining the prior written consent of GEOSURE; PROVIDED, HOWEVER, that 
without the consent of GEOSURE, VISTA and/or SUB shall assign its rights to 
purchase some or all of the partnership interests from the Partners to 
wholly-owned direct or indirect subsidiaries of SUB as long as such 
assignment does not affect the consideration to be received by the Partners 
or the covenants or obligations of VISTA or SUB hereunder.  Neither GEOSURE 
nor any Partner or DP may assign any or all of its rights hereunder, in whole 
or in part, without obtaining the prior written consent of VISTA.

       12.11  REMEDIES CUMULATIVE; SPECIFIC PERFORMANCE.  The rights and 
remedies of the parties hereto shall be cumulative (and not alternative).  
The parties to this Agreement agree that, in the event of any breach or 
threatened breach by any party to this Agreement of any covenant, obligation 
or other provision set forth in this Agreement for the benefit of any other 
party to this Agreement, such other party shall be entitled (in addition to 
any other remedy that may be available to it) to (A) a decree or order of 
specific performance or mandamus to enforce the observance and performance of 
such covenant, obligation or other provision, and (B) an injunction 
restraining such breach or threatened breach.

       12.12  WAIVER.

              (a)    No failure on the part of any Person to exercise any 
power, right, privilege or remedy under this Agreement, and no delay on the 
part of any Person in exercising any power, right, privilege or remedy under 
this Agreement, shall operate as a waiver of such power, right, privilege or 
remedy; and no single or partial exercise of any such power, right, privilege 
or remedy shall preclude any other or further exercise thereof or of any 
other power, right, privilege or remedy.

              (b)    No Person shall be deemed to have waived any claim 
arising out of this Agreement, or any power, right, privilege or remedy under 
this Agreement, unless the waiver of such claim, power, right, privilege or 
remedy is expressly set forth in a written instrument duly executed and 
delivered on behalf of such Person; and any such waiver shall not be 
applicable or have any effect except in the specific instance in which it is 
given.

       12.13  AMENDMENTS.  This Agreement may not be amended, modified, 
altered or supplemented other than by means of a written instrument duly 
executed and delivered on behalf of all of the parties hereto.

       12.14  SEVERABILITY.  In the event that any provision of this 
Agreement, or the application of any such provision to any Person or set of 
circumstances, shall be determined to be invalid, unlawful, void or 
unenforceable to any extent, the remainder of this Agreement, and the 
application of such provision to Persons or circumstances other than those as 
to which it is determined to be invalid, unlawful, void or unenforceable, 
shall not be impaired or otherwise affected and shall continue to be valid 
and enforceable to the fullest extent permitted by law.

                                       42

<PAGE>

       12.15  PARTIES IN INTEREST.  Except for the provisions of Sections 
7.8, 7.13 and 11, none of the provisions of this Agreement is intended to 
provide any rights or remedies to any Person other than the parties hereto 
and their respective successors and assigns (if any).

       12.16  ENTIRE AGREEMENT.  This Agreement and the other agreements 
referred to herein set forth the entire understanding of the parties hereto 
relating to the subject matter hereof and thereof and supersede all prior 
agreements and understandings among or between any of the parties relating to 
the subject matter hereof and thereof; provided, however, that any agreement 
with respect to confidentiality or proprietary information executed on behalf 
of VISTA and GEOSURE prior to the date hereof shall not be superseded by this 
Agreement and shall remain in effect in accordance with its terms and until 
the earlier of (a) the Effective Time, or (b) the date on which such 
agreement is terminated in accordance with its terms.

       12.17  CONSTRUCTION.

              (a)    For purposes of this Agreement, whenever the context 
requires: the singular number shall include the plural, and vice versa; the 
masculine gender shall include the feminine and neuter genders; the feminine 
gender shall include the masculine and neuter genders; and the neuter gender 
shall include the masculine and feminine genders.

              (b)    The parties hereto agree that any rule of construction 
to the effect that ambiguities are to be resolved against the drafting party 
shall not be applied in the construction or interpretation of this Agreement.

              (c)    As used in this Agreement, the words "include" and 
"including," and variations thereof, shall not be deemed to be terms of 
limitation, but rather shall be deemed to be followed by the words "without 
limitation."

       Except as otherwise indicated, all references in this Agreement to 
"Sections" and "Exhibits" are intended to refer to Sections hereof and 
Exhibits hereto.

                                       43

<PAGE>

       The parties hereto have caused this Agreement to be executed and 
delivered as of the date first written above.

                                         VISTA INFORMATION SOLUTIONS, INC.,

                                         a Delaware Corporation


                                         By:__________________________________
                                         Its:_________________________________


                                         SUB:


                                         VISTA Environmental Information, Inc.

                                         By:__________________________________
                                         Its:_________________________________


                                         GEOSURE, L.P.,

                                         a New York limited partnership

                                         By:    LRB Envio Enterprises, Inc.,
                                                   its general partner


                                         By:__________________________________
                                         Its:_________________________________


                                         By:    Chadwyck-Healey Ventures, Inc.
                                                   its general partner


                                         By:__________________________________
                                         Its:_________________________________


                                         THE PARTNERS OF GEOSURE:

                                         LRB Envio Enterprises, Inc.,


                                         By:__________________________________
                                         Its:_________________________________


                                         Chadwyck-Healey Ventures, Inc.


                                         By:__________________________________
                                         Its:_________________________________
                                         _____________________________________
                                         Sir Charles Chadwyck-Healey

                                       44

<PAGE>
                                         _____________________________________
                                         Charles Debare*


                                         _____________________________________
                                         Emily Unterberg Satloff*


                                         _____________________________________
                                         Ellen Unterberg Celli*


                                         _____________________________________
                                         Ann Unterberg*


                                         _____________________________________
                                         Benjamin J. Arno and
                                         Nancy Arno JTWROS*


                                         _____________________________________
                                         C.E. Unterberg Towbin 401K Plan*
                                         (f/k/a Unterberg Harris 401K Plan)
                                         FBO Robert C. Harris, Jr.


                                         _____________________________________
                                         C.E. Unterberg Towbin 401K Plan*
                                         (f/k/a Unterberg Harris 401K Plan)
                                         FBO Jody A. Owen


                                         _____________________________________
                                         C.E. Unterberg Towbin 401K Plan*
                                         (f/k/a Unterberg Harris 401K Plan)
                                         FBO C.E. Unterberg


                                         _____________________________________
                                         Thomas I. Unterberg*


                                         _____________________________________
                                         John Dexheimer*


                                         _____________________________________
                                         C.E. Unterberg Towbin 401K Plan*
                                         (f/k/a Unterberg Harris 401K Plan)
                                         FBO David S. Wachter


                                         _____________________________________
                                         James William Weil*

                                       45
<PAGE>

                                         _____________________________________
                                         Nancy Moyer*


                                         _____________________________________
                                         Andrew Celli & James Satloff*
                                         TTEE uad 5/13/93 FBO Rebecca Rose
                                         Celli


                                         _____________________________________
                                         Andrew Celli & James Satloff*
                                         TTEE uad 5/19/93
                                         FBO Dustin N. Satloff


                                         _____________________________________
                                         Andrew Arno*
                                         ACF Matthew Arno UGMA/NY


                                         _____________________________________
                                         C.E. Unterberg Capital Partners I,
                                         L.P.
                                         (f/k/a Unterberg Harris Capital
                                         Partners)*


                                         _____________________________________
                                         Ellen V. Celli & Emily V. Satloff*
                                         TTE FBO T.I. Unterberg's
                                         Grandchildren's
                                         Trust uad 4/26/93


                                         _____________________________________
                                         C.E. Unterberg, Towbin LLC
                                         (f/k/a Unterberg Harris, L.P.)


                                         _____________________________________
                                         Andrew Arno and Jane K. Arno, JTWROS*


                                         _____________________________________
                                         Elizabeth Arno*


                                         _____________________________________
                                         Mary Debare*


                                         _____________________________________
                                         C.E. Unterberg Towbin 401K Plan*
                                         (f/k/a Unterberg Harris 401K Plan)
                                         FBO Mel Lavitt

                                       46
<PAGE>

                                         _____________________________________
                                         C.E. Unterberg Towbin 401K Plan*
                                         (f/k/a Unterberg Harris 401K Plan)
                                         FBO Steven P. Novak


                                         _____________________________________
                                         Robert Matluck*


                                         _____________________________________
                                         Andrew Arno*
                                         ACF Jesse Arno UGMA/NY


                                         * By:________________________________
                                                   Attorney in Fact


                                         _____________________________________
                                         Dan S. Prickett

                                       47




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