Document:

Exhibit 10.10

                              FORM OF RCGI WARRANT

THE SECURITIES REPRESENTED BY THIS WARRANT HAVE NOT BEEN REGISTERED UNDER THE
SECURITIES ACT OF 1933, AS AMENDED, OR APPLICABLE STATE SECURITIES LAWS. THE
SECURITIES MAY NOT BE OFFERED FOR SALE, SOLD, TRANSFERRED OR ASSIGNED (I) IN THE
ABSENCE OF (A) AN EFFECTIVE REGISTRATION STATEMENT FOR THE SECURITIES UNDER THE
SECURITIES ACT OF 1933, AS AMENDED, OR APPLICABLE STATE SECURITIES LAWS OR (B)
AN OPINION OF COUNSEL, IN A GENERALLY ACCEPTABLE FORM, THAT REGISTRATION IS NOT
REQUIRED UNDER SAID ACT OR APPLICABLE STATE SECURITIES LAWS OR (II) UNLESS SOLD
PURSUANT TO RULE 144 UNDER SAID ACT. NOTWITHSTANDING THE FOREGOING, THE
SECURITIES MAY BE PLEDGED IN CONNECTION WITH A BONA FIDE MARGIN ACCOUNT OR OTHER
LOAN OR FINANCING ARRANGEMENT SECURED BY THE SECURITIES. ANY TRANSFEREE OF THIS
WARRANT SHOULD CAREFULLY REVIEW THE TERMS OF THIS WARRANT, INCLUDING SECTION
2(f) HEREOF. THE SECURITIES REPRESENTED BY THIS WARRANT MAY BE LESS THAN THE
NUMBER SET FORTH ON THE FACE HEREOF PURSUANT TO SECTION 2(f) HEREOF.

                            SONTERRA RESOURCES, INC.

                        WARRANT TO PURCHASE COMMON STOCK

Warrant No.: __________                           Number of Shares: ____________

Date of Issuance: ______, 2007

Sonterra Resources, Inc. (f/k/a River Capital Group, Inc.), a Delaware
corporation (the "Company"), hereby certifies that, for Ten United States
Dollars ($10.00) and other good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, ____________________, the
registered holder hereof or its permitted assigns (the "Holder"), is entitled,
subject to the terms set forth below, to purchase from the Company, at any time
or times on or after the date hereof, but not after 11:59 P.M. New York Time on
the Expiration Date (as defined herein) ________________ (________) [INSERT: a
number of shares equal to the quotient of (A) $1,500,000 divided by (B) 110% of
the Per Share Purchase Price (as defined in the Securities Exchange Agreement)]
fully paid nonassessable shares of Common Stock (as defined in Section 1(b)) of
the Company (the "Warrant Shares") at the Warrant Exercise Price (as defined in
Section 1(b)).

         Section 1.

                  (a)      Securities Exchange Agreement. This Warrant was
issued pursuant to Section 1 of that certain Securities Exchange and Additional
Note Purchase Agreement, dated as of _______, 2007, between the Company and The
Longview Fund, L.P., a California limited partnership (as such agreement may be
amended, modified, restated or supplemented from time to time as provided

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therein, the "Securities Exchange Agreement"), or issued in exchange or
substitution therefor or replacement thereof. Each capitalized term used, and
not otherwise defined, herein shall have the meaning ascribed thereto in the
Securities Exchange Agreement.

                  (b)      Definitions. The following words and terms used in
this Warrant shall have the following meanings:

                           (i)      "Approved Stock Plan" means any employee
benefit plan that has been approved by the Board of Directors and stockholders
of the Company after the date of the Securities Exchange Agreement, pursuant to
which the Company's securities may be issued to consultants, employees, officers
and directors for services provided to the Company.

                           (ii)     "Business Day" means any day other than
Saturday, Sunday or other day on which commercial banks in the City of New York
are authorized or required by law to remain closed.

                           (iii)    "Common Stock" means (A) the Company's
Common Stock, par value $.001 per share, and (B) any capital stock into which
such Common Stock shall have been changed or any capital stock resulting from a
reclassification of such Common Stock.

                           (iv)     "Convertible Securities" means any stock or
securities (other than Options) directly or indirectly convertible into or
exchangeable or exercisable for Common Stock.

                           (v)      "dollar" or "$" means U.S. dollars.

                           (vi)     "Exchange Act" means the Securities Exchange
Act of 1934, as amended.

                           (vii)    "Exempted Issuances" means (I) shares of
Common Stock issued or deemed to be issued by the Company pursuant to, and in
accordance with the terms of, an Approved Stock Plan, provided that the Company
does not (A) amend any Option to reduce its exercise price, (B) cancel any
Option and re-grant an Option with a lower exercise price than the original
exercise price of the cancelled Option, or (C) take any other action (whether in
the form of an amendment, cancellation or replacement grant) that has the effect
of repricing an Option, except pursuant to a proportional adjustment to the
exercise price and number of shares issuable thereunder in accordance with such
Approved Stock Plan to reflect a stock split dividend or stock combination with
respect to the Common Stock; (II) shares of Common Stock issued or deemed to be
issued by the Company upon the exercise of any Initial Officer Option, provided
that the terms of such Initial Officer Option or security are not amended or
otherwise modified on or after the Exchange Closing Date, and provided that the
exercise price thereof is not reduced, adjusted or otherwise modified and the
number of shares of Common Stock issuable thereunder is not increased (whether
by operation of, or in accordance with, the relevant governing documents or
otherwise) on or after the Exchange Closing Date, except pursuant to a
proportional adjustment to the exercise price and number of shares issuable
thereunder in accordance with the 2007 Option Plan to reflect a stock split
dividend or stock combination with respect to the Common Stock; (III) shares of
Common Stock issued or deemed to be issued by the Company upon exercise of this
Warrant or (IV) shares of Common Stock issued to C.K. Cooper & Company ("CKC")

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as compensation for services pursuant to the engagement letter dated July 25,
2007 between the Company and CKC.

                           (viii)   "Expiration Date" means the date that is
five (5) years after the Warrant Date (as defined in Section 12) or, if such
date does not fall on a Business Day, then the next Business Day.

                           (ix)     "Options" means any rights, warrants or
options to subscribe for or purchase any Common Stock or Convertible Securities.

                           (x)      "Person" means an individual, a limited
liability company, a partnership, a joint venture, a corporation, a trust, an
unincorporated organization or a government or any department or agency thereof
or any other legal entity.

                           (xi)     "Securities Act" means the Securities Act of
1933, as amended.

                           (xii)    "Trading Day" means any day on which the
Common Stock is traded on the Principal Market; provided that "Trading Day"
shall not include any day on which the Common Stock is scheduled to trade, or
actually trades, on the Principal Market for less than 4.5 hours.

                           (xiii)   "Warrant" means this Warrant and all
warrants issued in exchange, transfer or replacement thereof pursuant to the
terms of this Warrant.

                           (xiv)    "Warrant Exercise Price" shall be equal to,
with respect to any Warrant Share, $________ [INSERT: 110% of the Per Share
Purchase Price], subject to adjustment as hereinafter provided.

                           (xv)     "Weighted Average Price" means, for any
security as of any date, the dollar volume-weighted average price for such
security on its Principal Market during the period beginning at 9:30 a.m. New
York City time (or such other time as its Principal Market publicly announces is
the official open of trading) and ending at 4:00 p.m. New York City time (or
such other time as its Principal Market publicly announces is the official close
of trading) as reported by Bloomberg Financial Markets (or any successor
thereto) ("Bloomberg") through its "Volume at Price" functions, or if the
foregoing does not apply, the dollar volume-weighted average price of such
security in the over-the-counter market on the electronic bulletin board for
such security during the period beginning at 9:30 a.m. New York City time (or
such other time as such over-the-counter market publicly announces is the
official open of trading), and ending at 4:00 p.m. New York City time (or such
other time as such over-the-counter market publicly announces is the official
close of trading) as reported by Bloomberg, or, if no dollar volume-weighted
average price is reported for such security by Bloomberg for such hours, the
average of the highest closing bid price and the lowest closing ask price of any
of the market makers for such security as reported in the "pink sheets" by the
National Quotation Bureau, Inc. If the Weighted Average Price cannot be
calculated for such security on such date on any of the foregoing bases, the
Weighted Average Price of such security on such date shall be the fair market
value as mutually determined by the Company and the Holder. If the Company and
the Holder are unable to agree upon the fair market value of such security, then
such dispute shall be resolved pursuant to Section 2(a). All such determinations
shall be appropriately adjusted for any stock dividend, stock split, stock

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combination or other similar transaction during any period during which the
Weighted Average Price is being determined.

         Section 2.        Exercise of Warrant.
                           -------------------

                  (a)      Subject to the terms and conditions hereof, this
Warrant may be exercised by the Holder hereof then registered on the books of
the Company, in whole or in part, at any time on any Business Day on or after
the opening of business on the date hereof and prior to 11:59 P.M. New York City
time on the Expiration Date by (i) delivery of a written notice, in the form of
the exercise notice attached as Exhibit A hereto (the "Exercise Notice"), of the
Holder's election to exercise this Warrant, which notice shall specify the
number of Warrant Shares to be purchased and, if such exercise is conditioned
upon consummation of any transaction ("Exercise Trigger Transaction"), such
condition to exercise, (ii) (A) payment to the Company of an amount equal to the
product of the Warrant Exercise Price multiplied by the number of Warrant Shares
as to which this Warrant is being exercised (such product, the "Aggregate
Exercise Price") by wire transfer of immediately available funds (or by check if
the Company has not provided the Holder with wire transfer instructions for such
payment), or (B) notifying the Company that this Warrant is being exercised
pursuant to a Cashless Exercise (as defined in Section 2(e)), and (iii) if
required by Section 2(f) unless the Holder has previously delivered this Warrant
to the Company and it or a new replacement Warrant has not yet been delivered to
the Holder, the surrender to a common carrier for overnight delivery to the
Company as soon as practicable following such date, of this Warrant (or an
indemnification undertaking, in customary form, with respect to this Warrant in
the case of its loss, theft or destruction pursuant to Section 10); provided,
that if such Warrant Shares are to be issued in any name other than that of the
Holder, such issuance shall be deemed a transfer and the provisions of Section 7
shall be applicable. In the event of any exercise of the rights represented by
this Warrant in compliance with this Section 2(a), on the second (2nd) Business
Day (the "Warrant Share Delivery Date") following the date of its receipt of the
Exercise Notice, the Aggregate Exercise Price (or notice of Cashless Exercise)
and if required by Section 2(f) (unless the Holder has previously delivered this
Warrant to the Company and a new or replacement Warrant has not yet been
delivered to the Holder), this Warrant (or an indemnification undertaking, in
customary form, with respect to this Warrant in the case of its loss, theft or
destruction pursuant to Section 10) (the "Exercise Delivery Documents") (or, if
the exercise of this Warrant is conditioned upon the consummation of an Exercise
Trigger Transaction, on the later of such second (2nd) Business Day and the date
of consummation of such Exercise Trigger Transaction), (A) if the transfer agent
for the Common Stock is participating in The Depository Trust Company ("DTC")
Fast Automated Securities Transfer Program and the Holder is eligible to receive
shares through DTC, the Company shall credit such aggregate number of shares of
Common Stock to which the Holder shall be entitled to the Holder's or its
designee's balance account with DTC through its Deposit Withdrawal Agent
Commission system or (B) if not, the Company shall issue and deliver to the
address specified in the Exercise Notice, a certificate, registered in the name
of the Holder or its designee, for the number of shares of Common Stock to which
the Holder shall be entitled. Upon the latest of (x) the date of delivery of the
Exercise Notice, (y) the date of delivery of the Aggregate Exercise Price
referred to in clause (ii)(A) above or notification to the Company of a Cashless
Exercise referred to in Section 2(e), and (z) if the exercise of this Warrant is
conditioned upon the consummation of an Exercise Trigger Transaction, the date
of such consummation, the Holder shall be deemed for all purposes to have become
the Holder of record of the Warrant Shares with respect to which this Warrant

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has been exercised (the date thereof being referred to as the "Deemed Issuance
Date"), irrespective of the date of delivery of this Warrant as required by
clause (iii) above or the certificates evidencing such Warrant Shares. In the
case of a dispute as to the determination of the Warrant Exercise Price, the
Weighted Average Price of a security or the arithmetic calculation of the number
of Warrant Shares, the Company shall promptly issue to the Holder the number of
shares of Common Stock that is not disputed and shall submit the disputed
determinations or arithmetic calculations to the Holder via facsimile within two
(2) Business Days after receipt of the Holder's Exercise Notice. If the Holder
and the Company are unable to agree upon the determination of the Warrant
Exercise Price, the Weighted Average Price or arithmetic calculation of the
number of Warrant Shares within one (1) Business Day of such disputed
determination or arithmetic calculation being submitted to the Holder, then the
Company shall immediately submit via facsimile (i) the disputed determination of
the Warrant Exercise Price or the Weighted Average Price to an independent,
reputable investment banking firm agreed to by the Company and the Holder or
(ii) the disputed arithmetic calculation of the number of Warrant Shares to an
independent, reputable certified public accounting firm agreed to by the Company
and the Holder. The Company shall cause the investment banking firm or the
accountant, as the case may be, to perform the determinations or calculations
and notify the Company and the Holder of the results no later than two (2)
Business Days after the date it receives the disputed determinations or
calculations. Such investment banking firm's or accountant's determination or
calculation, as the case may be, shall be deemed conclusive absent manifest
error.

                  (b)      If this Warrant is submitted for exercise, as may be
required by Section 2(f), and unless the rights represented by this Warrant
shall have expired or shall have been fully exercised, the Company shall, as
soon as practicable and in no event later than three (3) Business Days after
receipt of this Warrant (the "Warrant Delivery Date") and at its own expense,
issue a new Warrant identical in all respects to this Warrant except it shall
represent rights to purchase the number of Warrant Shares purchasable
immediately prior to such exercise under this Warrant, less the number of
Warrant Shares with respect to which such Warrant is exercised (together with,
in the case of a Cashless Exercise, the number of Warrant Shares surrendered in
lieu of payment of the Exercise Price).

                  (c)      No fractional shares of Common Stock are to be issued
upon the exercise of this Warrant, but rather the number of shares of Common
Stock issued upon exercise of this Warrant shall be rounded up or down to the
nearest whole number (with 0.5 rounded up).

                  (d)      If the Company shall fail for any reason or for no
reason (x) to issue and deliver to the Holder within two (2) Business Days of
receipt of the Exercise Delivery Documents a certificate for the number of
shares of Common Stock to which the Holder is entitled or to credit the Holder's
balance account with DTC for such number of shares of Common Stock to which the
Holder is entitled upon the Holder's exercise of this Warrant or (y) to issue
and deliver to the Holder on the Warrant Delivery Date a new Warrant for the
number of shares of Common Stock to which such holder is entitled pursuant to
Section 2(b) hereof, if any, then the Company shall, in addition to any other
remedies under this Warrant or the Securities Exchange Agreement or otherwise
available to such holder, including any indemnification under Section 8 of the
Securities Exchange Agreement, pay as additional damages in cash to such holder
on each day after such second (2nd) Business Day that such shares of Common

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Stock are not issued and delivered to the Holder, in the case of clause (x)
above, or such third (3rd) Business Day that such Warrant is not delivered, in
the case of clause (y) above, an amount equal to the sum of (i) 0.5% of the
product of (A) the number of shares of Common Stock not issued to the Holder on
or prior to the Warrant Share Delivery Date and (B) the Weighted Average Price
of the Common Stock on the Warrant Share Delivery Date, in the case of the
failure to deliver Common Stock, and (ii) if the Company has failed to deliver a
Warrant to the Holder on or prior to the Warrant Delivery Date, 0.5% of the
product of (x) the number of shares of Common Stock issuable upon exercise of
the Warrant as of the Warrant Delivery Date, and (y) the Weighted Average Price
of the Common Stock on the Warrant Delivery Date; provided that in no event
shall cash damages accrue pursuant to this Section 2(d) during the period, if
any, in which any Warrant Shares are the subject of a bona fide dispute that is
subject to and being resolved pursuant to, and in compliance with the time
periods and other provisions of, the dispute resolution provisions of Section
2(a). Alternatively, at the election of the Holder made in the Holder's sole
discretion, the Company shall pay to the Holder, in lieu of the additional
damages referred to in the preceding sentence (but in addition to all other
available remedies that the Holder may pursue hereunder and under the Securities
Exchange Agreement (including indemnification pursuant to Section 8 thereof)),
110% of the amount that (A) the Holder's total purchase price (including
brokerage commissions, if any) for shares of Common Stock purchased to make
delivery in satisfaction of a sale by such holder of the shares of Common Stock
to which the Holder is entitled but has not received upon an exercise, exceeds
(B) the net proceeds received by the Holder from the sale of the shares of
Common Stock to which the Holder is entitled but has not received upon such
exercise.

                  (e)      Notwithstanding anything contained herein to the
contrary, at any time after the Warrant Date (as defined in Section 12) that all
of the Warrant Shares issuable hereunder are not registered and available for
resale pursuant to an effective registration statement under the Securities Act
in accordance with the Registration Rights Agreement, for any reason whatsoever,
including as a result of a Grace Period (as defined in the Registration Rights
Agreement), or as a result of a limitation on the number of Warrant Shares that
may be registered pursuant to Rule 415 under the Act, the Holder may, at its
election exercised in its sole discretion, exercise this Warrant in whole or in
part and, in lieu of making the cash payment otherwise contemplated to be made
to the Company upon such exercise in payment of the Aggregate Exercise Price,
elect instead to receive upon such exercise the "Net Number" of shares of Common
Stock determined according to the following formula (a "Cashless Exercise"):

         Net Number = (A x B) - (A x C)
                      -----------------
                              B

                  For purposes of the foregoing formula:

                           A= the total number of shares with respect to which
                           this Warrant is then being exercised;

                           B= the Weighted Average Price per share of Common
                           Stock on the Trading Day immediately preceding the
                           date of the delivery of the Exercise Notice; and

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                           C= the Warrant Exercise Price then in effect for the
                           applicable Warrant Shares at the time of such
                           exercise.

                  (f)      Book-Entry. Notwithstanding anything to the contrary
set forth herein, upon exercise of this Warrant in accordance with the terms
hereof, the Holder shall not be required to physically surrender this Warrant to
the Company unless it is being exercised for all of the Warrant Shares
represented by the Warrant. The Holder and the Company shall maintain records
showing the number of Warrant Shares exercised and issued and the dates of such
exercises or shall use such other method, reasonably satisfactory to the Holder
and the Company, so as not to require physical surrender of this Warrant upon
each such exercise. In the event of any dispute or discrepancy, such records of
the Company establishing the number of Warrant Shares to which the Holder is
entitled shall be controlling and determinative in the absence of error.
Notwithstanding the foregoing, if this Warrant is exercised as aforesaid, the
Holder may not transfer this Warrant unless the Holder first physically
surrenders this Warrant to the Company, whereupon the Company will forthwith
issue and deliver upon the order of the Holder a new Warrant of like tenor,
registered as the Holder may request, representing in the aggregate the
remaining number of Warrant Shares represented by this Warrant. The Holder and
any assignee, by acceptance of this Warrant, acknowledge and agree that, by
reason of the provisions of this paragraph, following exercise of any portion of
this Warrant, the number of Warrant Shares represented by this Warrant may be
less than the number stated on the face hereof.

         Section 3.        Covenants as to Common Stock. The Company hereby
covenants and agrees as follows:

                  (a)      This Warrant is, and any Warrants issued in
substitution for or replacement of this Warrant will upon issuance be, duly
authorized and validly issued.

                  (b)      All Warrant Shares that may be issued upon the
exercise of the rights represented by this Warrant will, upon issuance and
receipt of payment therefor from the Holder (including pursuant to a Cashless
Exercise, as applicable), be validly issued, fully paid and nonassessable and
free from all taxes, liens and charges with respect to the issue thereof.

                  (c)      During the period within which the rights represented
by this Warrant may be exercised, the Company will at all times have authorized
and reserved at least 100% of the number of shares of Common Stock needed to
provide for the exercise of the rights then represented by this Warrant.

                  (d)      The Company shall promptly secure the quotation or
listing of the Warrant Shares on the Principal Market (subject to official
notice of issuance upon exercise of this Warrant) and each other market or
exchange on which the Common Stock is traded or listed and shall maintain, so
long as any other shares of Common Stock shall be so traded or listed, such
listing of all Warrant Shares from time to time issuable upon the exercise of
this Warrant; and the Company shall so list on the Principal Market and each
other market or exchange on which the Common Stock is traded or listed and shall
maintain such listing of, any other shares of capital stock of the Company
issuable upon the exercise of this Warrant if and so long as any shares of the

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same class shall be listed on the Principal Market and each other market or
exchange on which such shares are traded or listed.

                  (e)      The Company will not, by amendment of its Certificate
of Incorporation or through any reorganization, transfer of assets,
consolidation, merger, dissolution, issue or sale of securities, or any other
voluntary action, avoid or seek to avoid the observance or performance of any of
the terms to be observed or performed by it hereunder, but will at all times in
good faith assist in the carrying out of all the provisions of this Warrant and
in the taking of all such action as may reasonably be requested by the Holder in
order to protect the exercise privilege of the Holder against impairment,
consistent with the tenor and purpose of this Warrant. Without limiting the
generality of the foregoing, the Company (i) will not increase the par value of
any shares of Common Stock receivable upon the exercise of this Warrant, and
(ii) will take all such actions as may be necessary or appropriate in order that
the Company may validly and legally issue fully paid and nonassessable shares of
Common Stock upon the exercise of this Warrant.

                  (f)      This Warrant will be binding upon any entity
succeeding to the Company by merger, consolidation or acquisition of all or
substantially all of the Company's assets.

         Section 4.        Taxes. The Company shall pay any and all taxes that
may be payable with respect to the issuance and delivery of Warrant Shares upon
exercise of this Warrant.

         Section 5.        Warrant Holder Not Deemed a Stockholder. Except as
expressly provided herein, the Holder, as holder of this Warrant shall not be
entitled to vote or be deemed the holder of stock of the Company for any purpose
(other than to the extent that the Holder is deemed to be a beneficial holder of
Warrant Shares under applicable securities laws), or otherwise have any of the
rights of a stockholder of the Company or any right to vote, give or withhold
consent to any corporate action (whether any reorganization, issue of stock,
reclassification of stock, consolidation, merger, conveyance or otherwise),
receive notice of meetings, or receive dividends or subscription rights, prior
to the Deemed Issuance Date of the Warrant Shares that such holder is then
entitled to receive upon the due exercise of this Warrant. In addition, nothing
contained in this Warrant shall be construed as imposing any liabilities on such
holder to purchase any securities (except to the extent set forth in an Exercise
Notice that has been delivered by the Holder to the Company) or as a stockholder
of the Company, whether such liabilities are asserted by the Company or by
creditors of the Company. Notwithstanding the foregoing, the Company will
provide the Holder with copies of the same notices (without duplication if the
Holder is also a stockholder of the Company) and other information given to the
stockholders of the Company generally, contemporaneously with the giving thereof
to the stockholders.

         Section 6.        Representations of Holder. The holder of this
Warrant, by the acceptance hereof, represents that it is acquiring this Warrant,
and upon exercise hereof (other than pursuant to a Cashless Exercise) will
acquire the Warrant Shares, for its own account and not with a view towards, or
for resale in connection with, the public sale or distribution of this Warrant
or the Warrant Shares, except pursuant to sales registered, or exempted from
registration, under the Securities Act; provided, however, that by making the
representations herein, the Holder does not agree to hold this Warrant or any of
the Warrant Shares for any minimum or other specific term and reserves the right
to dispose of this Warrant and the Warrant Shares at any time in accordance with

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or pursuant to a registration statement or an exemption under the Securities
Act. The holder of this Warrant further represents, by acceptance hereof, that,
as of this date, such holder is an "accredited investor" as such term is defined
in Rule 501(a)(3) of Regulation D promulgated by the Securities and Exchange
Commission under the Securities Act. Each delivery of an Exercise Notice, other
than in connection with a Cashless Exercise, shall constitute confirmation at
such time by the Holder of the representations concerning the Warrant Shares set
forth in the first two sentences of this Section 6, unless contemporaneously
with the delivery of such Exercise Notice, the Holder notifies the Company in
writing that it is not making such representations (a "Representation Notice").
If the Holder delivers a Representation Notice in connection with an exercise,
it shall be a condition to such Holder's exercise of this Warrant and the
Company's obligations set forth in Section 2 in connection with such exercise,
that the Company receive such other representations as the Company considers
reasonably necessary to assure the Company that the issuance of its securities
upon exercise of this Warrant shall not violate any United States or state
securities laws.

         Section 7.        Ownership and Transfer.
                           ----------------------

                  (a)      The Company shall maintain at its principal executive
offices (or such other office or agency of the Company as it may designate by
notice to the Holder), a register for this Warrant, in which the Company shall
record the name and address of the person in whose name this Warrant has been
issued, as well as the name and address of each transferee. The Company may
treat the person in whose name any Warrant is registered on the register as the
owner and holder thereof for all purposes, notwithstanding any notice to the
contrary, but in all events recognizing any transfers made in accordance with
the terms of this Warrant.

                  (b)      This Warrant and the rights granted hereunder shall
be assignable by the Holder hereof in accordance with the Securities Exchange
Agreement.

                  (c)      The Company is obligated to register the Warrant
Shares for resale under the Securities Act pursuant to the Registration Rights
Agreement and the initial holder of this Warrant (and certain assignees thereof)
is entitled to the registration rights in respect of the Warrant Shares as set
forth in the Registration Rights Agreement.

         Section 8.        Adjustment of Warrant Exercise Price and Number of
Warrant Shares. The Warrant Exercise Price and the number of shares of Common
Stock issuable upon exercise of this Warrant shall be adjusted from time to time
as follows:

                  (a)      Adjustment of Warrant Exercise Price and Number of
Shares upon Issuance of Common Stock. If and whenever on or after the Warrant
Date (as defined in Section 12), the Company issues or sells, or is deemed to
have issued or sold, any shares of Common Stock (including the issuance or sale
of shares of Common Stock owned or held by or for the account of the Company,
but excluding Exempted Issuances), for a consideration per share less than a
price (the "Applicable Price") equal to the Warrant Exercise Price in effect
immediately prior to such issuance or sale, then immediately after such issue or
sale the Warrant Exercise Price then in effect shall be reduced to an amount
equal to such consideration per share. Upon each such adjustment of the Warrant
Exercise Price pursuant to the immediately preceding sentence, the number of
shares of Common Stock acquirable upon exercise of this Warrant shall be

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adjusted to the number of shares determined by multiplying the Warrant Exercise
Price in effect immediately prior to such adjustment by the number of shares of
Common Stock acquirable upon exercise of this Warrant immediately prior to such
adjustment and dividing the product thereof by the Warrant Exercise Price
resulting from such adjustment.

                  (b)      Effect on Warrant Exercise Price of Certain Events.
For all purposes of this Section 8, including for purposes of determining the
adjusted Warrant Exercise Price under Section 8(a) above and for purposes of
determining whether the Company has issued or sold, or shall be deemed to have
issued or sold, any shares of Common Stock for a consideration per share less
than a price equal to the Applicable Price), the following shall be applicable:

                           (i)      Issuance of Options. If the Company in any
manner grants or sells any Options (other than pursuant to an Approved Stock
Plan) and the lowest price per share for which one share of Common Stock is
issuable upon the exercise of any such Option or upon conversion, exchange or
exercise of any Convertible Securities issuable upon exercise of any such Option
is less than the Applicable Price, then such share of Common Stock shall be
deemed to be outstanding and to have been issued and sold by the Company at the
time of the granting or sale of such Option for such price per share. For
purposes of this Section 8(b)(i), the "lowest price per share for which one
share of Common Stock is issuable upon exercise of any such Option or upon
conversion, exchange or exercise of any Convertible Security issuable upon
exercise of any such Option" shall be equal to the sum of the lowest amounts of
consideration (if any) received or receivable by the Company with respect to any
one share of Common Stock upon the granting or sale of the Option, upon exercise
of the Option and upon conversion, exchange or exercise of any Convertible
Security issuable upon exercise of such Option. No further adjustment of the
Warrant Exercise Price shall be made upon the actual issuance of such Common
Stock or of such Convertible Securities upon the exercise of such Options or
upon the actual issuance of such Common Stock upon conversion, exchange or
exercise of such Convertible Securities.

                           (ii)     Issuance of Convertible Securities. If the
Company in any manner issues or sells any Convertible Securities and the lowest
price per share for which one share of Common Stock is issuable upon the
conversion, exchange or exercise thereof is less than the Applicable Price, then
such share of Common Stock shall be deemed to be outstanding and to have been
issued and sold by the Company at the time of the issuance or sale of such
Convertible Securities for such price per share. For the purposes of this
Section 8(b)(ii), the "lowest price per share for which one share of Common
Stock is issuable upon such conversion, exchange or exercise" shall be equal to
the sum of the lowest amounts of consideration (if any) received or receivable
by the Company with respect to one share of Common Stock upon the issuance or
sale of the Convertible Security and upon conversion, exchange or exercise of
such Convertible Security. No further adjustment of the Warrant Exercise Price
shall be made upon the actual issuance of such Common Stock upon conversion,
exchange or exercise of such Convertible Securities, and if any such issue or
sale of such Convertible Securities is made upon exercise of any Options for
which adjustment of the Warrant Exercise Price had been or are to be made
pursuant to other provisions of this Section 8(b), no further adjustment of the
Warrant Exercise Price shall be made by reason of such issue or sale.

                                       10
<PAGE>

                           (iii)    Change in Option Price or Rate of
Conversion. If the purchase, exchange or exercise price provided for in any
Options, the additional consideration, if any, payable upon the issue,
conversion, exchange or exercise of any Convertible Securities, or the rate at
which any Options or Convertible Securities are convertible into or exchangeable
or exercisable for Common Stock changes at any time, the Warrant Exercise Price
in effect at the time of such change shall be adjusted to the Warrant Exercise
Price that would have been in effect at such time had such Options or
Convertible Securities provided for such changed purchase, exchange or exercise
price, additional consideration or changed conversion rate, as the case may be,
at the time initially granted, issued or sold, and the number of shares of
Common Stock acquirable hereunder shall be correspondingly readjusted. For
purposes of this Section 8(b)(iii), if the terms of any Option or Convertible
Security that was outstanding as of the date of issuance of this Warrant are
changed in the manner described in the immediately preceding sentence, then such
Option or Convertible Security and the Common Stock deemed issuable upon
exercise, conversion or exchange thereof shall be deemed to have been issued as
of the date of such change. No adjustment shall be made if such adjustment would
result in an increase of the Warrant Exercise Price then in effect.

                           (iv)     Calculation of Consideration Received. In
case any Options are issued in connection with the issue or sale of other
securities of the Company, together comprising one integrated transaction or
series of related transactions, (A) the Options will be deemed to have been
issued for a consideration equal to the greatest of (I) $0.01, (II) the specific
aggregate consideration, if any, allocated to such Options, and (III) the
Black-Scholes Value (as defined below) of such Options (the greatest of (I),
(II) and (III), the "Option Consideration") and, for purposes of applying the
provisions of this Section 8, the Option Consideration shall be allocated pro
rata among all the shares of Common Stock issuable upon exercise of such Options
to determine the consideration per each such share of Common Stock and (B) the
other securities will be deemed to have been issued for an aggregate
consideration equal to the aggregate consideration received by the Company for
the Options and other securities (determined as provided below with respect to
each share of Common Stock represented thereby), less the Option Consideration.
If any Common Stock, Options or Convertible Securities are issued or sold or
deemed to have been issued or sold for cash, the consideration received therefor
will be deemed to be the net amount received by the Company therefor. If any
Common Stock, Options or Convertible Securities are issued or sold for a
consideration other than cash, the amount of such consideration received by the
Company will be the fair value of such consideration, except where such
consideration consists of marketable securities, in which case the amount of
consideration received by the Company will be the Weighted Average Price of such
securities on the date of receipt of such securities. If any Common Stock,
Options or Convertible Securities are issued to the owners of the non-surviving
entity in connection with any merger in which the Company is the surviving
entity, the amount of consideration therefor will be deemed to be the fair value
of such portion of the net assets and business of the non-surviving entity as is
attributable to such Common Stock, Options or Convertible Securities, as the
case may be. The fair value of any consideration other than cash or securities
will be determined jointly by the Company and the Holder. If such parties are
unable to reach agreement within ten (10) days after the occurrence of an event
requiring valuation (the "Valuation Event"), the fair value of such
consideration will be determined within five (5) Business Days after the tenth
(10th) day following the Valuation Event by an independent, reputable appraiser
jointly selected by the Company and the Holder. The determination of such
appraiser shall be final and binding upon all parties absent manifest error, and
the fees and expenses of such appraiser shall be borne by the Company.

                                       11
<PAGE>

                           (v)      Record Date. If the Company takes a record
of the Holders of Common Stock for the purpose of entitling them (1) to receive
a dividend or other distribution payable in Common Stock, Options or in
Convertible Securities or (2) to subscribe for or purchase Common Stock, Options
or Convertible Securities, then such record date will be deemed to be the date
of the issue or sale of the shares of Common Stock deemed to have been issued or
sold upon the declaration of such dividend or the making of such other
distribution or the date of the granting of such right of subscription or
purchase, as the case may be.

                           (vi)     Black-Scholes Value. The "Black-Scholes
Value" of any Options shall mean the sum of the amounts resulting from applying
the Black-Scholes pricing model to each such Option, which calculation is made
with the following inputs: (i) the "option striking price" being equal to the
lowest exercise price possible under the terms of such Option on the date of the
issuance of such Option (the "Valuation Date"), (ii) the "interest rate" being
equal to the Federal Reserve US H.15 T Note Treasury Constant Maturity 1 Year
rate on the Valuation Date (as reported by Bloomberg through its "ALLX H15T"
function (accessed by typing "ALLX H15T" [GO] on a Bloomberg terminal, and
inserting the date of the Valuation Date and then looking at the row entitled
"Treas Const Mat 1 Year" under the column entitled "Previous Value")), or if
such rate is not available then such other similar rate mutually agreed to by
the Company and the Holder, (iii) the "time until option expiration" being the
time from the Valuation Date until the expiration date of such Option, (iv) the
"current stock price" being equal to the Weighted Average Price of the Common
Stock on the Valuation Date, (v) the "volatility" being the 100-day historical
volatility of the Common Stock as of the Valuation Date (as reported by the
Bloomberg "HVT" screen), and (vi) the "dividend rate" being equal to zero.
Within three (3) Business Days after the Valuation Date, each of the Company and
the Holder shall deliver to the other a written calculation of its determination
of the Black-Scholes Value of the Options. If the Holder and the Company are
unable to agree upon the calculation of the Black-Scholes Value of the Options
within five (5) Business Days of the Valuation Date, then the Company shall
submit via facsimile the disputed calculation to an independent, reputable
investment banking firm (jointly selected by the Company and the Holder) within
seven (7) Business Days of the Valuation Date. The Company shall cause such
investment banking firm to perform the calculations and notify the Company and
the Holder of the results no later than ten (10) Business Days after the
Valuation Date. Such investment banking firm's calculation of the Black-Scholes
Value of the Options shall be deemed conclusive absent manifest error. The
Company shall bear the fees and expenses of such investment banking firm for
providing such calculation.

                  (c)      Adjustment of Warrant Exercise Price upon Subdivision
or Combination of Common Stock. If the Company at any time after the date of
issuance of this Warrant subdivides (by any stock split, stock dividend,
recapitalization or otherwise) its outstanding shares of Common Stock into a
greater number of shares, the Warrant Exercise Price in effect immediately prior
to such subdivision will be proportionately reduced and the number of shares of
Common Stock obtainable upon exercise of this Warrant will be proportionately
increased. If the Company at any time after the date of issuance of this Warrant
combines (by combination, reverse stock split or otherwise) its outstanding
shares of Common Stock into a smaller number of shares, the Warrant Exercise

                                       12
<PAGE>

Price in effect immediately prior to such combination will be proportionately
increased and the number of shares of Common Stock obtainable upon exercise of
this Warrant will be proportionately decreased. Any adjustment under this
Section 8(d) shall become effective at the close of business on the date the
subdivision or combination becomes effective or, if earlier, the record date
with respect to the subdivision or combination.

                  (d)      Dividends; Distributions of Assets. If the Company
shall declare or make any dividend or other distribution of its assets (or
rights to acquire its assets) to holders of Common Stock, by way of return of
capital or otherwise (including any dividend or other distribution of cash,
stock or other securities, property or options by way of a dividend, spin off,
reclassification, corporate rearrangement or other similar transaction) (a
"Distribution"), at any time after the issuance of this Warrant, then, in each
such case, the Holder shall be entitled to receive such Distribution, and the
Company shall make such Distribution to the Holder, exactly as if the Holder had
exercised this Warrant in full (and, as a result, had held all of the shares of
Common Stock that the Holder would have received upon such exercise) immediately
prior to the record date for such Distribution, or if there is no record
therefor, immediately prior to the effective date of such Distribution (but
without the Holder's actually having to so exercise this Warrant).

                  (e)      Certain Events. If any event occurs of the type
contemplated by the provisions of this Section 8 but not expressly provided for
by such provisions (including the granting of stock appreciation rights, phantom
stock rights or other rights with equity features), then the Company's Board of
Directors will make an appropriate adjustment in the Warrant Exercise Price and
the number of shares of Common Stock obtainable upon exercise of this Warrant so
as to protect the rights of the Holder; provided that no such adjustment will
increase the Warrant Exercise Price or decrease the number of shares of Common
Stock obtainable as otherwise determined pursuant to this Section 8.

                  (f)      Notices.
                           -------

                           (i)      As soon as reasonably practicable, but in no
event later than two (2) Business Days, upon any adjustment of the Warrant
Exercise Price, the Company will give written notice thereof to the Holder,
setting forth in reasonable detail, and certifying, the calculation of such
adjustment; provided, however, that neither the timing of giving any such notice
nor any failure by the Company to give such a notice shall effect any such
adjustment or the effective date thereof.

                           (ii)     The Company will give written notice to the
Holder at least ten (10) days prior to the date on which the Company closes its
books or takes a record (A) with respect to any dividend or distribution upon
the Common Stock, (B) with respect to any pro rata subscription offer to holders
of Common Stock or (C) for determining rights to vote with respect to any
Organic Change (as defined below), dissolution or liquidation.

                           (iii)    The Company will also give written notice to
the Holder at least ten (10) days prior to the date on which any Organic Change,
dissolution or liquidation will take place.

                                       13
<PAGE>

         Section 9.        Purchase Rights; Reorganization, Reclassification,
Consolidation, Merger or Sale.

                  (a)      In addition to any adjustments pursuant to Section 8
above, if at any time the Company grants, issues or sells any Options,
Convertible Securities or rights to purchase stock, warrants, securities or
other property pro rata to the record holders of any class of its capital stock
(the "Purchase Rights"), then the Holder will be entitled to acquire, upon the
terms applicable to such Purchase Rights, the aggregate Purchase Rights that
such holder could have acquired if such holder had held the number of shares of
Common Stock acquirable upon complete exercise of this Warrant immediately
before the date on which a record is taken for the grant, issuance or sale of
such Purchase Rights, or, if no such record is taken, the date as of which the
record holders of Common Stock are to be determined for the grant, issue or sale
of such Purchase Rights.

                  (b)      Any recapitalization, reorganization,
reclassification, consolidation, merger, sale of all or substantially all of the
Company's assets to another Person or other transaction that is effected in such
a way that holders of Common Stock are entitled to receive (either directly or
upon subsequent liquidation) stock, securities or assets with respect to or in
exchange for Common Stock is referred to herein as "Organic Change." Prior to
the consummation of any (i) sale of all or substantially all of the Company's
assets to an acquiring Person or (ii) other Organic Change following which the
Company is not a surviving entity, the Company will secure from the Person
purchasing such assets or the successor resulting from such Organic Change (in
each case, the "Acquiring Entity") a written agreement (in form and substance
satisfactory to the Holder) to deliver to the Holder, in exchange for this
Warrant, a security of the Acquiring Entity evidenced by a written instrument
substantially similar in form and substance to this Warrant and satisfactory to
the Holder (including, an adjusted Warrant Exercise Price equal to the value for
the Common Stock reflected by the terms of such consolidation, merger or sale,
and exercisable for a corresponding number of shares of Common Stock acquirable
and receivable upon exercise of this Warrant, if the value so reflected is less
than the Warrant Exercise Price in effect immediately prior to such
consolidation, merger or sale). Prior to the consummation of any other Organic
Change, the Company shall make appropriate provision (in form and substance
satisfactory to the Holder) to ensure that the Holder will thereafter have the
right to acquire and receive in lieu of or in addition to (as the case may be)
the shares of Common Stock immediately theretofore acquirable and receivable
upon the exercise of such this Warrant, such shares of stock, securities or
assets that would have been issued or payable in such Organic Change with
respect to or in exchange for the number of shares of Common Stock that would
have been acquirable and receivable upon the exercise of this Warrant as of the
date of such Organic Change.

         Section 10.       Lost, Stolen, Mutilated or Destroyed Warrant. If this
Warrant is lost, stolen, mutilated or destroyed, the Company shall promptly, on
receipt of an indemnification undertaking in customary form (or in the case of a
mutilated Warrant, the Warrant), issue a new Warrant of like denomination and
tenor as this Warrant so lost, stolen, mutilated or destroyed.

         Section 11.       Notice. Any notices, consents, waivers or other
communications required or permitted to be given under the terms of this Warrant
must be in writing and will be deemed to have been delivered: (i) upon receipt,
when delivered personally; (ii) upon receipt, when sent by facsimile (provided

                                       14
<PAGE>

confirmation of transmission is mechanically or electronically generated and
kept on file by the sending party); or (iii) one (1) Business Day after deposit
with a nationally recognized overnight delivery service, in each case properly
addressed to the party to receive the same. The addresses and facsimile numbers
for such communications shall be:

         If to the Company:

                  Sonterra Resources, Inc.
                  300 East Sonterra Boulevard, Suite 1220
                  San Antonio, Texas
                  Facsimile: 210-545-3317
                  Attention: Michael J. Pawelek

                  With a copy to:

                  Thompson & Knight
                  333 Clay Street, Suite 3300
                  Houston, Texas 77002
                  Facsimile: 832-397-8110
                  Attention: Dallas Parker, Esq.

If to the initial Holder, to it at the address and facsimile number set forth in
the Securities Exchange Agreement, with copies to the Holder's representatives
as set forth in the Securities Exchange Agreement or, in the case of any other
Holder or any other Person named above, at such other address and/or facsimile
number and/or to the attention of such other person as the recipient party has
specified by written notice to the other party at least five (5) Business Days
prior to the effectiveness of such change. Written confirmation of receipt (A)
given by the recipient of such notice, consent, waiver or other communication,
(B) mechanically or electronically generated by the sender's facsimile machine
containing the time, date, recipient facsimile number and an image of the first
page of such transmission or (C) provided by a nationally recognized overnight
delivery service shall be rebuttable evidence of personal service, receipt by
facsimile or deposit with a nationally recognized overnight delivery service in
accordance with clause (i), (ii) or (iii) above, respectively.

         Section 12.       Date. The date of this Warrant is ___________
[INSERT: Exchange Closing Date] (the "Warrant Date"). This Warrant, in all
events, shall be wholly void and of no effect after 11:59 P.M., New York City
time, on the Expiration Date, except that notwithstanding any other provisions
hereof, the provisions of Section 7 shall continue in full force and effect
after such date as to any Warrant Shares or other securities issued upon the
exercise of this Warrant.

         Section 13.       Amendment and Waiver. Except as otherwise provided
herein, the provisions of this Warrant may be amended and the Company may take
any action herein prohibited, or omit to perform any act herein required to be
performed by it, only if the Company has obtained the written consent of the
Holder.

                                       15
<PAGE>

         Section 14.       Descriptive Headings; Governing Law. The descriptive
headings of the several sections and paragraphs of this Warrant are inserted for
convenience only and do not constitute a part of this Warrant. All questions
concerning the construction, validity, enforcement and interpretation of this
Warrant shall be governed by the internal laws of the State of New York, without
giving effect to any choice of law or conflict of law provision or rule (whether
of the State of New York or any other jurisdiction) that would cause the
application of the laws of any jurisdiction other than the State of New York.

         Section 15.       Rules of Construction. Unless the context otherwise
requires, (a) all references to Articles, Sections, Schedules or Exhibits are to
Articles, Sections, Schedules or Exhibits contained in or attached to this
Warrant, (b) each accounting term not otherwise defined in this Warrant or the
Securities Exchange Agreement has the meaning assigned to it in accordance with
GAAP, (c) words in the singular or plural include the singular and plural and
pronouns stated in either the masculine, the feminine or neuter gender shall
include the masculine, feminine and neuter and (d) the use of the word
"including" in this Warrant shall be by way of example rather than limitation.

         Section 16.       Signatures. In the event that any signature to this
Warrant or any amendment hereto is delivered by facsimile transmission or by
e-mail delivery of a ".pdf" format data file, such signature shall create a
valid and binding obligation of the party executing (or on whose behalf such
signature is executed) with the same force and effect as if such facsimile or
".pdf" signature page were an original thereof. Notwithstanding the foregoing,
the Company shall be obligated to deliver to the Holder an originally executed
Warrant. At the request of any party, each other party shall promptly re-execute
an original form of this Warrant or any amendment hereto and deliver the same to
the other party. No party hereto shall raise the use of a facsimile machine or
e-mail delivery of a ".pdf" format data file to deliver a signature to this
Warrant or any amendment hereto or the fact that such signature was transmitted
or communicated through the use of a facsimile machine or e-mail delivery of a
".pdf" format data file as a defense to the formation or enforceability of a
contract, and each party hereto forever waives any such defense.

                                  * * * * * *

                                       16
<PAGE>

         IN WITNESS WHEREOF, the Company has caused this Warrant to be executed
as of the ____ day of _________, 200_.

                                       SONTERRA RESOURCES, INC.

                                       By:____________________________________

                                       Name:__________________________________

                                       Title:_________________________________

                                       17
<PAGE>

                              EXHIBIT A TO WARRANT
                              --------------------

                                EXERCISE NOTICE

        TO BE EXECUTED BY THE REGISTERED HOLDER TO EXERCISE THIS WARRANT

                            SONTERRA RESOURCES, INC.

         The undersigned holder hereby exercises the right to purchase
_________________ of the shares of Common Stock ("Warrant Shares") of SONTERRA
RESOURCES, INC. (f/k/a River Capital Group, Inc.), a Delaware corporation (the
"Company"), evidenced by the attached Warrant (the "Warrant"). Capitalized terms
used herein and not otherwise defined shall have the respective meanings set
forth in the Warrant.

         1. Form of Warrant Exercise Price. The holder intends that payment of
the Warrant Exercise Price shall be made as:

           ____________      a "Cash Exercise" with respect to _________________
                             Warrant Shares; and/or

           ____________      a "Cashless Exercise" with respect to _____________
                             Warrant Shares.

         2. Payment of Warrant Exercise Price. In the event that the Holder has
elected a Cash Exercise with respect to some or all of the Warrant Shares to be
issued pursuant hereto, the Holder shall pay the Aggregate Exercise Price in the
sum of $___________________ to the Company in accordance with the terms of the
Warrant.

         3. Exercise Trigger Transaction. This exercise of the Warrant is
conditioned upon the consummation of the following Exercise Trigger Transaction:
__________________________*

         4. Delivery of Warrant Shares. The Company shall deliver __________
Warrant Shares in accordance with the terms of the Warrant in the following name
and to the following address:

Issue to:_______________________________________________________________________

         Facsimile Number:______________________________________________________

         DTC Participant Number and Name (if electronic book entry
         transfer):_____________________________________________________________

         Account Number (if electronic book entry transfer):____________________

Date: _______________ __, ______

Name of Registered Holder of this Warrant

By:______________________________________
Name:
Title:

__________________________________

*   No such condition applies if left blank

                                      -18-
<PAGE>

                                 ACKNOWLEDGMENT
                                 --------------

         The Company hereby acknowledges this Exercise Notice and hereby directs
[TRANSFER AGENT] to issue the above indicated number of shares of Common Stock
in accordance with the Transfer Agent Instructions dated ________________, 200_
from the Company and acknowledged and agreed to by [TRANSFER AGENT].

                                       SONTERRA RESOURCES, INC.

                                       By:____________________________________

                                       Name:__________________________________

                                       Title:_________________________________

                                      -19-
<PAGE>

                              EXHIBIT B TO WARRANT
                              --------------------

                             FORM OF WARRANT POWER

FOR VALUE RECEIVED, the undersigned does hereby assign and transfer to
________________, Federal Identification No. __________, a warrant to purchase
____________ shares of the capital stock of Sonterra Resources, Inc. (f/k/a
River Capital Group, Inc.), a Delaware corporation, represented by warrant
certificate no. _____, standing in the name of the undersigned on the books of
said corporation. The undersigned does hereby irrevocably constitute and appoint
______________, attorney to transfer the warrants of said corporation, with full
power of substitution in the premises.

Dated:  _________, 200_

                                       _________________________________________

                                       Name:__________________________________

                                       Title:_________________________________

                                      -20-Exhibit 10.11

                                FORM OF RCGI NOTE

THE SECURITIES REPRESENTED HEREBY HAVE NOT BEEN REGISTERED UNDER THE SECURITIES
ACT OF 1933, AS AMENDED, OR APPLICABLE STATE SECURITIES LAWS. THE SECURITIES MAY
NOT BE OFFERED FOR SALE, SOLD, TRANSFERRED OR ASSIGNED (I) IN THE ABSENCE OF (A)
AN EFFECTIVE REGISTRATION STATEMENT FOR THE SECURITIES UNDER THE SECURITIES ACT
OF 1933, AS AMENDED, OR APPLICABLE STATE SECURITIES LAWS OR (B) AN OPINION OF
COUNSEL, IN A GENERALLY ACCEPTABLE FORM, THAT REGISTRATION IS NOT REQUIRED UNDER
SAID ACT OR APPLICABLE STATE SECURITIES LAWS OR (II) UNLESS SOLD PURSUANT TO
RULE 144 UNDER SAID ACT. NOTWITHSTANDING THE FOREGOING, THE SECURITIES MAY BE
PLEDGED IN CONNECTION WITH A BONA FIDE MARGIN ACCOUNT OR OTHER LOAN OR FINANCING
ARRANGEMENT SECURED BY THE SECURITIES. ANY TRANSFEREE OF THIS NOTE SHOULD
CAREFULLY REVIEW THE TERMS OF THIS NOTE, INCLUDING SECTION 3(d) HEREOF. THE
PRINCIPAL AMOUNT REPRESENTED BY THIS NOTE MAY BE LESS THAN THE AMOUNTS SET FORTH
ON THE FACE HEREOF PURSUANT TO SECTION 3(d) HEREOF.

                               SENIOR SECURED NOTE
                               -------------------

_____ __, 200_

Note No.: [ _________ ]                                              $[________]

         FOR VALUE RECEIVED, SONTERRA RESOURCES, INC. (f/k/a River Capital
Group, Inc.), a Delaware corporation (the "Company"), hereby promises to pay to
the order of The Longview Fund, L.P. or its permitted assigns (the "Holder") the
principal amount of [___] Dollars ($[______]) when due, whether upon maturity,
acceleration, redemption or otherwise, and to pay interest ("Interest") on the
unpaid principal balance hereof on each Interest Payment Date (as defined in
Section 2) and upon maturity, or earlier upon acceleration or prepayment
pursuant to the terms hereof, at the Applicable Interest Rate (as defined in
Section 2). Interest on this Note payable on each Interest Payment Date and upon
maturity, or earlier upon acceleration or prepayment pursuant to the terms
hereof, shall accrue from the Issuance Date (as defined in Section 2) and shall
be computed on the basis of a 365-day year and actual days elapsed.

         (1) Payments of Principal and Interest. All payments under this Note
shall be made in lawful money of the United States of America by wire transfer
of immediately available funds to such account as the Holder may from time to
time designate by written notice in accordance with the provisions of this Note.
Interest on the Principal shall be paid quarterly in arrears on each Interest
Payment Date (as defined in Section 2). The Company has no right, but under
certain circumstances has an obligation, to make payments of Principal of this
Note prior to the Maturity Date (as defined in Section 2), except as set forth
in Section 3 hereof. Whenever any amount expressed to be due by the terms of
this Note is due on any day that is not a Business Day (as defined in Section
2), the same shall instead be due on the next succeeding day that is a Business
Day. This Note and all Other Notes (as defined in Section 2) issued by the
Company pursuant to the Securities Exchange Agreement (as defined in Section 2)

<PAGE>

on the Exchange Closing Date and any Additional Closing Dates, and all notes
issued in exchange or substitution therefor or replacement or addition thereof
are collectively referred to in this Note as the "Notes."

         (2) Certain Defined Terms. Each capitalized term used in this Note, and
not otherwise defined, shall have the meaning ascribed thereto in the Securities
Exchange and Additional Note Purchase Agreement, dated as of July __, 2007,
pursuant to which this Note was originally issued (as such agreement may be
amended, restated, supplemented or modified from time to time as provided
therein, the "Securities Exchange Agreement"). For purposes of this Note, the
following terms shall have the following meanings:

                  (a)      "3-Month LIBOR Rate" means the London Interbank
Offered Rate of LIBOR with respect to a three-month period for deposits of
United States Dollars as reported by Bloomberg Financial Markets (or any
successor thereto, "Bloomberg") at approximately 10:00 a.m. (New York time)
through its "LIBOR Rates" function (accessed by typing "LR" [GO] on a Bloomberg
terminal, and looking at the row entitled "3 MONTH" and under the column
entitled "DOLLAR LIBOR") (or such other page as may replace that page on that
service, or such other service as may be selected jointly by the Company and the
holders of the Notes). If such rate appears on the Bloomberg LIBOR Rates page on
any date of determination of the 3-Month LIBOR Rate (a "LIBOR Determination
Date"), the 3-Month LIBOR Rate for such date of determination will be such rate.
If on any LIBOR Determination Date such rate does not appear on the Bloomberg
LIBOR Rates page, the Company and the holders of Notes representing at least
two-thirds (2/3) of the aggregate principal amount of the Notes then outstanding
will jointly request each of four major reference banks in the London interbank
market, as selected jointly by the Company and such holders to provide the
Company with its offered quotation for United States dollar deposits for the
upcoming three-month period, to prime banks in the London interbank market at
approximately 4:00 p.m., London time on any such LIBOR Determination Date and in
a principal amount that is representative for a single transaction in United
States Dollars in such market at such time. If at least two reference banks
provide the Company with offered quotations, 3-Month LIBOR Rate on such LIBOR
Determination Date will be the arithmetic mean of all such quotations. If on
such LIBOR Determination Date fewer than two of the reference banks provide the
Company with offered quotations, 3-Month LIBOR Rate on such LIBOR Determination
Date will be the arithmetic mean of the offered per annum rates that three major
banks in New York City selected jointly by the Company and the holders of Notes
representing at least two-thirds (2/3) of the aggregate principal amount of the
Notes then outstanding quote at approximately 11:00 A.M. in New York City on
such LIBOR Determination Date for three-month United States dollar loans to
leading European banks, in a principal amount that is representative for a
single transaction in United States dollars in such market at such time. If
these New York City quotes are not available, then the 3-Month LIBOR Rate
determined on such LIBOR Determination Date will continue to be 3-Month LIBOR
Rate as then currently in effect on such LIBOR Determination Date.

                  (b)      "Applicable Interest Rate" means the Interest Rate,
or, for so long as an Event of Default shall have occurred and be continuing,
the Default Rate.

                                       2
<PAGE>

                  (c)      "Business Day" means any day other than Saturday,
Sunday or other day on which commercial banks in the city of New York are
authorized or required by law to remain closed.

                  (d)      "Cash and Cash Equivalents" means (I) cash, (II)
certificates of deposit or time deposits, having in each case a tenor of not
more than six (6) months, issued by any United States commercial bank or any
branch or agency of a non-United States bank licensed to conduct business in the
United States having combined capital and surplus of not less than $250,000,000,
and (III) money market funds, provided that substantially all of the assets of
such funds consist of securities of the type described in clauses (I) or (II)
immediately above, all as determined in accordance with GAAP applied on a
consistent basis.

                  (e)      "Change of Control" means (i) the consolidation,
merger or other business combination of the Company with or into another Person
(other than (A) a consolidation, merger or other business combination in which
holders of the Company's voting power immediately prior to the transaction
continue after the transaction to hold, directly or indirectly, a majority of
the combined voting power of the surviving entity or entities entitled to vote
generally for the election of a majority of the members of the board of
directors (or their equivalent if other than a corporation) of such entity or
entities, or (B) pursuant to a migratory merger effected solely for the purpose
of changing the jurisdiction of incorporation of the Company), (ii) the sale or
transfer of all or substantially all of the Company's assets (including, for the
avoidance of doubt, the sale of all or substantially all of the assets of the
Included Subsidiaries in the aggregate); or (iii) the consummation of a
purchase, tender or exchange offer made to and accepted by the holders of more
than the 50% of the outstanding RCGI Common Shares, provided that such shares
include more than 50% of the outstanding RCGI Common Shares held by Persons
other than the Holder and its Related Persons.

                  (f)      "Collateral Agent" shall have the meaning ascribed to
such term in the Security Agreement.

                  (g)      "Default Rate" means the per annum interest rate
equal to the sum of (i) the Interest Rate plus (ii) two percent (2.0%) (i.e.,
200 basis points).

                  (h)      "Dollars" or "$" means United States Dollars.

                  (i)      "Excluded Taxes" means, with respect to the Holder,
or any other recipient of payment to be made by or on account of any obligations
of the Company or any of the Subsidiaries under the Notes, the Securities
Exchange Agreement or under any other Transaction Document, income or franchise
taxes imposed on (or measured by) such recipient's net income by the United
States of America or such other jurisdiction under the laws of which such
recipient is organized or its principal offices are located.

                  (j)      "Financial Covenant Test Failure" means that, as of
any date of determination, (A) the Revenue from the sale of hydrocarbons and the
provision of related services for the three-month period ending on such date is
less than the Required Revenue as of such date, (B) the Total Proved Reserves as
of such date are less than the Required Total Proved Reserves as of such date,
or (C) the PRV Ratio as of such date is less than the Required PRV Ratio as of
such date.

                                       3
<PAGE>

                  (k)      "Financial Covenant Test Failure Amount" means that,
in the event that there is a Financial Covenant Test Failure, as of the date of
any determination, an amount equal to the sum of:

                  (i)      the product of (A) the result of (I) one (1) minus
                  (II) the quotient of the Revenue for the three-month period
                  ended on such date, divided by the Required Revenue for the
                  three-month period ended on such date, multiplied by (B) the
                  aggregate outstanding principal amount of all Notes then
                  outstanding; plus

                  (ii)     the product of (A) the result of (I) one (1) minus
                  (II) the quotient of the PRV Ratio as of such date, divided by
                  the Required PRV Ratio as of such date, multiplied by (B) the
                  aggregate outstanding principal amount of all Notes then
                  outstanding; plus

                  (iii)    the product of (A) the result of (I) one (1) minus
                  (II) the quotient of the Total Proved Reserves as of such
                  date, divided by the Required Total Proved Reserves as of such
                  date, multiplied by (B) the aggregate outstanding principal
                  amount of all Notes then outstanding.

                  (l)      "Governmental Authority" means the government of the
United States of America or any other nation, or any political subdivision
thereof, whether state, provincial or local, or any agency, authority,
instrumentality, regulatory body, court, central bank or other entity exercising
executive, legislative, judicial, taxing, regulatory or administration powers or
functions of or pertaining to government over the Company, or any of their
respective properties, assets or undertakings.

                  (m)      "Indemnified Taxes" means Taxes other than Excluded
Taxes.

                  (n)      "Interest Amount" means as of any date, with respect
to any Principal, all accrued and unpaid Interest (including any Interest at the
Default Rate) on such Principal through and including such date.

                  (o)      "Interest Payment Date" means the first Business Day
of each calendar quarter, beginning with the calendar quarter that commences on
[Insert: the first day of the first calendar quarter commencing after the
Issuance Date], through and including the last calendar quarter that commences
prior to the Maturity Date.

                  (p)      "Interest Rate" shall initially mean the per annum
interest rate equal to the sum of (a) the 3-Month LIBOR Rate in effect on the
Issuance Date and (b) eight and one quarter of one percent (8.25%) (i.e., 825
basis points). Thereafter, the "Interest Rate" shall adjust as of the first
Business Day of each calendar quarter thereafter (or, if not a London Banking
Day, then on the First London Banking Day thereafter) to equal the per annum
interest rate equal to the sum of (x) the 3-Month LIBOR Rate in effect on such
date and (y) eight and one quarter of one percent (8.25%) (i.e., 825 basis
points).

                                       4
<PAGE>

                  (q)      "Issuance Date" means the original date of issuance
of this Note pursuant to the Securities Exchange Agreement, regardless of any
exchange or replacement hereof.

                  (r)      "London Banking Day" means a day on which dealings in
U.S. dollar deposits are transacted in the London interbank market.

                  (s)      "Maturity Date" means August 31, 2010, unless such
date is not a Business Day, in which case "Maturity Date" shall mean the first
Business Day following August 31, 2010.

                  (t)      "Original Principal Amount" means [_______] Dollars
($[_______]).

                  (u)      "Other Notes" means all of the senior secured notes,
other than this Note, that have been issued by the Company pursuant to the
Securities Exchange Agreement and all notes issued in exchange or substitution
therefor, addition thereto or replacement thereof.

                  (v)      "PDNP" as of any date of determination, means the
total proved developed non-producing reserves of the Company and the Included
Subsidiaries, determined as of such date of determination in accordance with SEC
guidelines based on an independent reserve report prepared in good faith by the
Petroleum Engineer in accordance with the Petroleum Engineer Report Guidelines
attached as Exhibit A hereto (an "Independent Reserve Report"); provided,
however, that PDNP shall mean zero unless (A) it is based upon an Independent
Reserve Report (or an update thereof prepared (but not certified) by the
Petroleum Engineer, which update includes all material adjustments to the
amounts set forth in the most recent Independent Reserve Report to reflect the
Company's and the Included Subsidiaries' oil and gas drilling, exploration,
development and production since the date of such Independent Reserve Report (a
"Reserve Update")) that was current as of a date within 92 days of such date of
determination, (B) the Company has publicly disclosed the PDNP in a Periodic
Report as of a date within 274 days of such date of determination (based on an
Independent Reserve Report that was current as of such date of determination),
(C) the PDNP is based upon the same Independent Reserve Report or Reserve Update
on which the PDP and PUD are based as of such date of determination, and (D) if
the PDNP is not based upon an Independent Reserve Report (or a Reserve Update)
that was current as of such date of determination, the Company reasonably
believes, based upon its own analysis conducted in good faith and reflecting the
Company's and the Included Subsidiaries' oil and gas drilling, exploration,
development and production since the date of the Independent Reserve Report (or
Reserve Update) on which the PDNP is based (the "Recent Production") (and has
certified to the Holder in the applicable Officer's Certificate to the Holder
that it so reasonably believes), that the PDP is not less than that disclosed in
the Independent Reserve Report (or Reserve Update) on which the PDNP is based.

                  (w)      "PDP" means the total proved developed producing
reserves of the Company and the Included Subsidiaries, determined in accordance
with SEC guidelines based on an Independent Reserve Report; provided, however,
that PDP shall mean zero unless (A) it is based upon an Independent Reserve
Report (or a Reserve Update) that was current as of a date within 92 days of
such date of determination, (B) the Company has publicly disclosed the PDNP in a

                                       5
<PAGE>

Periodic Report as of a date within 274 days of such date of determination
(based on an Independent Reserve Report that was current as of such date of
determination), (C) the PDP is based upon the same Independent Reserve Report or
Reserve Update on which the PDNP and PUD are based as of such date of
determination, and (D) if the PDP is not based upon an Independent Reserve
Report (or a Reserve Update) that was current as of such date of determination,
the Company reasonably believes, based upon its own analysis conducted in good
faith and reflecting the Recent Production (and has certified to the Holder in
the applicable Officer's Certificate that it so reasonably believes), that the
PDP is not less than that disclosed in the Independent Reserve Report (or
Reserve Update) on which the PDP is based.

                  (x)      "Periodic Report" means a quarterly report on Form
10-Q or 10-QSB, or an annual report on Form 10-K or 10-KSB under the 1934 Act.

                  (y)      "Person" means an individual, a limited liability
company, a partnership, a joint venture, a corporation, a trust, an
unincorporated organization or a government or any department or agency thereof
or any other legal entity.

                  (z)      "Petroleum Engineer" means a petroleum engineer
selected and engaged by the Company and approved by the holders of Notes
representing at least two-thirds (2/3) of the aggregate principal amount of the
Notes then outstanding.

                  (aa)     "Prepayment Notice" means a written notice from the
Company to Holder indicating the Company's commitment to prepay a specified
amount of Principal, together with the applicable Interest Amount and Prepayment
Premium with respect thereto on the applicable Prepayment Date.

                  (bb)     "Prepayment Premium" means, with respect to any
prepayment of Principal, (1) at any time during the period beginning on the
Exchange Closing Date and ending on and including the day immediately preceding
the first anniversary of the Exchange Closing Date, 3% of the amount of
Principal so prepaid or required to be prepaid, (2) at any time during the
period beginning on and including the first anniversary of the Exchange Closing
Date and ending on and including the day immediately preceding the second
anniversary of the Exchange Closing Date, 2% of the amount of Principal so
prepaid or required to be prepaid, (3) at any time during the period beginning
on and including the second anniversary of the Exchange Closing Date and ending
on and including the day immediately preceding the Maturity Date, 1% of the
amount of Principal so prepaid or required to be prepaid; provided, that (i) in
respect of any prepayment of Principal occurring on or after the Company's
public announcement of a pending, proposed or intended Change of Control, but
before the abandonment or termination thereof and public announcement of such
abandonment or termination, or (ii) in respect of any prepayment of Principal
pursuant to Section 4(b) occurring as a result of an Event of Default set forth
in clause (i), (ii), (iii), (iv), (vii), (viii), (ix), (x), (xi), (xii), (xiii),
(xiv) or (xv) of Section 4(a), "Prepayment Premium" shall mean an amount equal
to twenty percent (20%) of the amount of Principal so prepaid or required to be
prepaid.

                  (cc)     "Principal" means the outstanding principal amount of
this Note as of any date.

                                       6
<PAGE>

                  (dd)     "Pro Rata Financial Covenant Test Failure Amount"
means, as of the date of any determination, an amount equal to the sum of (i)
the product of (A) a fraction, of which the numerator is the outstanding
Principal as of such date, and of which the denominator is the aggregate
outstanding principal amount of all Notes as of such date, multiplied by (B) the
Financial Covenant Test Failure Amount, and (ii) the Interest Amount with
respect to such Principal as of the date such amount is paid to the Holder.

                  (ee)     "PRV Ratio" means, as of any date of determination,
the quotient of:

                           (I) the result of:

                                    (i) (A) the product of the aggregate actual
                                    PDP and PDNP mcfe of the Company's and the
                                    Included Subsidiaries' oil and gas
                                    properties and interests in which the
                                    holders of the Notes have a valid, first
                                    priority, perfected security interest as of
                                    such date of determination, multiplied by
                                    (B) the relevant hub spot price as of such
                                    date of determination multiplied by (C) 40%;
                                    plus

                                    (ii) the product of (A) the actual PUD mcfe
                                    of such properties multiplied by (B)
                                    relevant hub spot price multiplied by (C)
                                    15%; plus

                                    (iii) the product of (A) the fair market
                                    value as of such date of determination of
                                    the pipeline systems and separation or tank
                                    farm facilities with respect to such
                                    properties that are owned by the Company or
                                    the Included Subsidiaries and in which the
                                    holders of the Notes have a valid, first
                                    priority, perfected security interest, as
                                    determined in good faith by a Qualified
                                    Appraiser, multiplied by (B) (1) on or prior
                                    to the one year anniversary of the Exchange
                                    Closing Date, 40% or (2) after the one year
                                    anniversary of the Exchange Closing Date but
                                    on or prior to the two year anniversary of
                                    the Exchange Closing Date, 20% and (3)
                                    thereafter, 0%; plus

                                    (iv) the aggregate Cash and Cash Equivalents
                                    of the Company and the Included
                                    Subsidiaries, the aggregate hydrocarbon
                                    receivables of the Company and the Included
                                    Subsidiaries, and the market value of hedges
                                    of the Company and the Included
                                    Subsidiaries, each as of such date of
                                    determination, as set forth in the financial
                                    statements included in the Periodic Report
                                    for the fiscal quarter or year ended on such
                                    date of determination; minus

                                    (vii) the aggregate hedge margin collateral
                                    of the Company and the Included
                                    Subsidiaries, the aggregate hydrocarbon

                                       7
<PAGE>

                                    payables of the Company and the Included
                                    Subsidiaries, and the aggregate accrued cash
                                    expenses of the Company and the Included
                                    Subsidiaries, each as of such date of
                                    determination, as set forth in the financial
                                    statements included in the Periodic Report
                                    for the fiscal quarter or year ended on such
                                    date of determination; minus

                                    (x) the aggregate Indebtedness for borrowed
                                    money of the Company and the Subsidiaries
                                    due within one year (excluding the Notes),
                                    as of such date of determination, as set
                                    forth in the financial statements included
                                    in the Periodic Report for the fiscal
                                    quarter or year ended on such date of
                                    determination ;

                           divided by

                           (II)     the aggregate outstanding principal amount
of all Notes.

                  (ff)     "PUD" means the total proved undeveloped reserves of
the Company and the Included Subsidiaries, determined in accordance with SEC
guidelines based on an Independent Reserve Report; provided, however, that PUD
shall mean zero unless (A) it is based upon an Independent Reserve Report (or a
Reserve Update) that was current as of a date within 92 days of such date of
determination, (B) the Company has publicly disclosed the PDNP in a Periodic
Report as of a date within 274 days of such date of determination (based on an
Independent Reserve Report that was current as of such date of determination),
(C) the PUD is based upon the same Independent Reserve Report or Reserve Update
on which the PDNP and PDP are based as of such date of determination, and (D) if
the PDNP is not based upon an Independent Reserve Report (or a Reserve Update)
that was current as of such date of determination, the Company reasonably
believes, based upon its own analysis conducted in good faith and reflecting the
Recent Production (and has certified in the applicable Officer's Certificate
that it so reasonably believes), that the PUD is not less than that disclosed in
the Independent Reserve Report (or Reserve Update) on which the PUD is based.

                  (gg)      "Qualified Appraiser" means a qualified, independent
appraiser selected and engaged by the Company and approved by holders of Notes
representing at least two-thirds (2/3) of the aggregate principal amount of the
Notes then outstanding.

                  (hh)     "Required PRV Ratio" means, with respect to any date
set forth below, the ratio set forth below opposite such date:

                  Date                                                Ratio
                  ----                                                -----
                  Exchange Closing Date
                  (if prior to September 30, 2007)             `      1.00

                  September 30, 2007                                  1.00

                  December 31, 2007                                   1.25

                                       8
<PAGE>

                  March 31, 2008                                      1.50

                  June 30, 2008 and
                  the last day of each fiscal quarter thereafter      1.75

                  (ii)     "Required Revenue" means, with respect to any fiscal
quarter (i) ending on or after September 30, 2007 and prior to or on June 30,
2008, $300,000 and (ii) ending after June 30, 2008, $500,000.

                  (jj)     "Required Total Proved Reserves" means, with respect
to any date set forth below, the amount set forth below opposite such date:

                                                                    Total Proved
                  Date                                                Reserves
                  ----                                                --------
                  Exchange Closing Date
                  (if prior to September 30, 2007)                    2.0  BCFE

                  September 30, 2007                                  2.0  BCFE

                  December 31, 2007                                   4.0  BCFE

                  March 31, 2008                                      5.0  BCFE

                  June 30, 2008 and the last day
                  of each fiscal quarter thereafter                   7.0 BCFE

                  (kk)      "Revenue" means the consolidated revenues of the
Company and the Included Subsidiaries determined in accordance with GAAP,
consistently applied; provided, however, that revenues of an Included Subsidiary
that is not a wholly-owned Subsidiary shall only be recognized in the percentage
amount of the Company or its wholly owned Subsidiaries' percentage ownership of
the Capital Stock of such Included Subsidiary; provided, however, that in
determining Revenue for any measurement period commencing prior to the Exchange
Closing and ending after the Exchange Closing, Revenue shall include the
revenues of Sonterra, determined in accordance with GAAP, consistently applied,
from the first day of such measurement period through (but not including) the
Exchange Closing Date.

                  (ll)     "SEC" means the U.S. Securities and Exchange
Commission, or any successor thereto.

                  (mm)      "Total Proved Reserves" means, as of any date of
determination, the sum of the PUD, the PDNP and the PDP of the oil and gas
properties and interests of the Company and the Included Subsidiaries in which
the holder of the Notes have a valid, first priority, perfected security
interest; provided, however, there shall be excluded, in making such
calculation, such portion, if any, of the PUD in excess of the portion that
would result in the PUD constituting 40% of such sum.

                  (nn)     "U.S." means the United States of America.

                                       9
<PAGE>

         (3)      Principal Payments.
                  ------------------

                  (a)      Optional Principal Prepayments.
                           ------------------------------

                           (i)      General. The Company shall have the right at
         any time not less than ten (10) Business Days following the receipt by
         Holder of a Prepayment Notice from the Company, to voluntarily prepay
         this Note (an "Optional Prepayment"), in whole or in part, for an
         amount in cash equal to the sum of (A) the Principal then being prepaid
         pursuant to this Section 3(a), (B) the Interest Amount with respect to
         such Principal as of the applicable prepayment date (the "Optional
         Prepayment Date") and (C) the Prepayment Premium with respect to such
         Principal as of the Optional Prepayment Date (collectively, the
         "Required Prepayment Amount"); provided, however, that the Company may
         not take such action unless it simultaneously takes the same action
         with respect to the same percentage of the outstanding principal amount
         of each outstanding Other Note.

                           (ii)     Mechanics of Optional Prepayments. If the
         Company has delivered a Prepayment Notice in accordance with Section
         3(a)(i), then the Company shall pay to the Holder the Required
         Prepayment Amount in cash by wire transfer of immediately available
         funds to an account designated by the Holder. The delivery of a
         Prepayment Notice by the Company to the Holder shall be irrevocable,
         and the failure of the Company to prepay the Required Prepayment Amount
         set forth therein on the applicable Optional Prepayment Date shall
         constitute an Event of Default hereunder.

                           (iii)    Condition to Optional Prepayment.
         Notwithstanding anything to the contrary contained in this Section
         3(a), the Company shall not be permitted to deliver any Prepayment
         Notice or to effect any Optional Prepayment at any time after any Event
         of Default, or any event that with the passage of time or the giving of
         notice (or both) and without being cured would constitute an Event of
         Default, has occurred and is continuing.

                  (b)      Mandatory Prepayment Upon Financial Covenant Test
Failure.

                           (i)      On the second Business Day following each
         date that the Company files or is required to file a Periodic Report
         (which in each case shall disclose the Company's Revenue for the
         three-month period ending on the last day of the period covered by such
         Periodic Report, and the Total Proved Reserves, the PRV Ratio and any
         Financial Covenant Test Failure Amount as of the last day of the period
         covered by such Periodic Report, and details of the calculations and
         components thereof), the Company shall deliver to the Holder, by
         facsimile or overnight courier, a certificate executed by its principal
         financial officer (an "Officer's Certificate") (1) certifying as to the
         accuracy of the Periodic Report and of the Total Proved Reserves, the
         PRV Ratio and any Financial Covenant Test Failure Amount disclosed
         therein, (2) if there is no Financial Covenant Test Failure disclosed
         therein, certifying that there was no Financial Covenant Test Failure
         as of the last day of the period covered by such Periodic Report, (3)

                                       10
<PAGE>

         if there was a Financial Covenant Test Failure as of the last day of
         the period covered by such Periodic Report, certifying as to the
         Holder's Pro Rata Financial Covenant Test Failure Amount as of the last
         day of the period covered by such Periodic Report. Notwithstanding
         anything contained herein to the contrary, no Officer's Certificate
         delivered by the Company to any Holder shall contain any material
         non-public information regarding the Company or any of the
         Subsidiaries. Upon the occurrence of any Financial Covenant Test
         Failure, the Company shall immediately prepay, without demand or notice
         by the Holder, by wire transfer of immediately available funds to such
         account as the Holder may from time to time designate, an amount equal
         to the Holder's Pro Rata Financial Covenant Test Failure Amount.

                           (ii)     In the case of a bona fide dispute as to the
         determination of the Revenue, PUD, PDP, PDNP, or PRV Ratio or the
         arithmetic calculation of any Financial Covenant Test Failure Amount,
         the Company shall pay any amount that is not disputed and shall
         transmit an explanation of the disputed determinations or arithmetic
         calculations to the Holder via facsimile within two (2) Business Days
         of the occurrence of the dispute. If the Holder and the Company are
         unable to agree upon the determination of the Revenue, PUD, PDP, PDNP,
         or PRV Ratio or the arithmetic calculation of any Financial Covenant
         Test Failure Amount within two (2) Business Days of such disputed
         determination or arithmetic calculation being transmitted to the
         Holder, then the Company shall promptly (and in any event within two
         (2) Business Days) submit via facsimile (A) the disputed determination
         of the PUD, PDP, PDNP, or PRV Ratio to a qualified, independent
         petroleum engineer and/or a qualified, independent appraiser (other
         than the Petroleum Engineer and the Qualified Appraiser), as
         applicable, agreed to by the Company and the holders of the Notes
         representing at least two-thirds (2/3) of the aggregate principal
         amounts of the Notes then outstanding as to which such determination is
         being made, or (B) the disputed arithmetic calculation of the Revenue
         or such Financial Covenant Test Failure Amount to an independent,
         outside certified public accountant, agreed to by the Company and the
         holder of the Notes representing at least two-thirds (2/3) of the
         aggregate principal amounts of the Notes then outstanding as to which
         such determination is being made. The Company shall direct the
         petroleum engineer, the appraiser, or the accountant, as the case may
         be, to perform the determinations or calculations, at the Company's
         expense, and notify the Company and the Holder of the results no later
         than two (2) Business Days from the time it receives the disputed
         determinations or calculations. Such petroleum engineer's, appraiser's,
         or accountant's determination or calculation, as the case may be, shall
         be binding upon all parties absent manifest error.

                  (c)      Mandatory Payment by the Company on Maturity Date. If
any Principal remains outstanding on the Maturity Date, then the Holder shall
surrender this Note, duly endorsed for cancellation to the Company, and such
Principal shall be redeemed by the Company as of the Maturity Date by payment on
the Maturity Date to the Holder, by wire transfer of immediately available
funds, of an amount equal to 100% of such Principal.

                                       11
<PAGE>

                  (d)      Surrender of Note. Notwithstanding anything to the
contrary set forth in this Note, upon any prepayment of this Note in accordance
with its terms, the Holder shall not be required to physically surrender this
Note to the Company unless all of the Principal is being repaid and the related
Interest Amount and all other obligations payable under this Note (including any
applicable Prepayment Premium) have been paid in full. The Holder and the
Company shall maintain records showing the Principal repaid and the date(s) of
such repayments or shall use such other method, reasonably satisfactory to the
Holder and the Company, so as not to require physical surrender of this Note
upon each such repayment. In the event of any dispute or discrepancy, such
records of the Holder establishing the Principal to which the Holder is entitled
shall be controlling and determinative in the absence of manifest error. The
Holder and any assignee, by acceptance of this Note, acknowledge and agree that,
by reason of the provisions of this paragraph, following partial repayment of
any portion of this Note, the Principal of this Note may be less than the
principal amount stated on the face hereof.

         (4)      Defaults and Remedies.
                  ---------------------

                  (a)      Events of Default. An "Event of Default" shall mean
any of: (i) default in payment of any Principal, Required Prepayment Amount, or
Pro Rata Financial Covenant Test Failure Amount under this Note or any Other
Note when and as due; (ii) default in payment of any Interest or other amount
due on this Note or any Other Note that is not included in an amount described
in the immediately preceding clause (i) that is not cured within three Business
Days from the date such or other amount was due; (iii) failure by the Company
for 10 days to comply with any other provision of this Note in all material
respects; (iv) any default in payment of at least $100,000, individually or in
the aggregate, under or acceleration prior to maturity of, or any event or
circumstances arising such that, any person is entitled, or could, with the
giving of notice and/or lapse of time and/or the fulfillment of any condition
and/or the making of any determination, become entitled, to require repayment
before its stated maturity of, or to take any step to enforce any security for,
any mortgage, indenture or instrument under which there may be issued or by
which there may be secured or evidenced any indebtedness for money borrowed of
at least $100,000 by the Company or any of the Subsidiaries, or for money
borrowed the repayment of at least $100,000 of which is guaranteed by the
Company or any of the Subsidiaries, whether such indebtedness or guarantee now
exists or shall be created hereafter; (v) the Company or any of the Subsidiaries
pursuant to or within the meaning of any Bankruptcy Law (as defined below); (A)
commences a voluntary case or applies for a receiving order; (B) consents to the
entry of an order for relief against it in an involuntary case or consents to
any involuntary application for a receiving order; (C) consents to the
appointment of a Custodian of it or any of the Subsidiaries for all or
substantially all of its property; (D) makes a general assignment for the
benefit of its creditors; or (E) admits in writing that it is generally unable
to pay its debts as the same become due; (vi) an involuntary case or other
proceeding is commenced directly against the Company or any of the Subsidiaries
seeking liquidation, reorganization or other relief with respect to it or its
Indebtedness under any Bankruptcy Law now or hereafter in effect or seeking the
appointment of a trustee, receiver, liquidator, custodian or other similar
official of it or any substantial part of its property, and such involuntary
case or other Bankruptcy Law proceeding remains undismissed and unstayed for a
period of 45 days, or an order of relief is entered against the Company as
debtor under the Bankruptcy Laws as are now or hereafter in effect; (vii) the
Company or any of the Subsidiaries breaches any covenant or other term or
condition of the Security Documents; (viii) the Company or any of the

                                       12
<PAGE>

Subsidiaries breaches any covenant or other term or condition of the Securities
Exchange Agreement, the Warrants, this Note or any other Transaction Document,
except, in the case of a breach of a covenant or other term that is curable,
only if such breach continues for a period of at least 20 days; (ix) the Company
breaches, or otherwise does not comply with, Section 4(u), or any of the
provisions of Section 5, of the Securities Exchange Agreement; (x) one or more
judgments, non-interlocutory orders or decrees shall be entered by a U.S. state
or federal or a foreign court or administrative agency of competent jurisdiction
against the Company or any of the Subsidiaries involving, in the aggregate, a
liability (to the extent not covered by independent third-party insurance) as to
any single or related series of transactions, incidents or conditions, of
$100,000 or more, and the same shall remain unsatisfied, unvacated, unbonded or
unstayed pending appeal for a period of 30 days after the entry thereof; (xi)
there shall occur a Change of Control; (xii) any representation, warranty,
certification or statement made by the Company or any of the Subsidiaries in the
Securities Exchange Agreement, the Registration Rights Agreement, the Warrants,
this Note, the Security Documents or any other Transaction Document or in any
certificate, financial statement or other document delivered pursuant to any
such Transaction Document is incorrect in any material respect when made (or
deemed made); (xiii) any Lien created by any of the Security Documents shall at
any time fail to constitute a valid and perfected Lien on all of the Collateral
purported to be secured thereby, subject to no prior or equal Lien except
Permitted Liens, or the Company or any of the Subsidiaries shall so assert,
(xiv) the Company fails to file, or is determined to have failed to file, in a
timely manner any Periodic Report or Current Report (other than a Current Report
that is required solely pursuant to Item 1.01, 1.02, 2.03, 2.04, 2.05, 2.06,
4.02(a) or 5.02(e) of Form 8-K as in effect on the Issuance Date) required to be
filed with the SEC pursuant to the 1934 Act (provided that any filing made
within the time period permitted by Rule 12b-25 under the 1934 Act and pursuant
to a timely filed Form 12b-25 shall, for purposes of this clause (xiv), be
deemed to be timely filed) or the Revenue, the Total Proved Reserves, the PRV
Ratio or any Financial Covenant Test Failure Amount disclosed in any Periodic
Report is not true and correct in all material respects; or (xv) the Company
fails to deliver an Officer's Certificate pursuant to Section 3(b)(i) within
five (5) days after the date such Officer's Certificate is required to be
delivered pursuant to Section 3(b)(i), any Officer's Certificate delivered to
the Holder does not contain any of the information required to be included
therein pursuant to Section 3(b)(i), or any of the information contained in any
Officer's Certificate delivered to the Holder is not true, correct and complete
in all material respects. The term "Bankruptcy Law" means Title 11, U.S. Code,
or any similar U.S. federal or state law or law of any applicable foreign
government or political subdivision thereof for the relief of debtors. The term
"Custodian" means any receiver, trustee, assignee, liquidator or similar
official under any Bankruptcy Law. Within two Business Days after the occurrence
of any Event of Default, the Company shall deliver written notice thereof to the
Holder.

                  (b)      Remedies. If an Event of Default occurs and is
continuing, the Holder may declare all or any portion of this Note, including
any or all amounts due hereunder, to be due and payable immediately, except that
in the case of an Event of Default arising from events described in clauses (v)
and (vi) of Section 4(a) above, all amounts due hereunder shall immediately
become due and payable without further action or notice. In addition to any
remedy the Holder may have under this Note, the Security Documents and the other
Transaction Documents, such unpaid amounts shall bear interest at the Default
Rate, and any payment of Principal prior to the scheduled maturity thereof as a
result of acceleration under this Section 4(b) shall be accompanied by the

                                       13
<PAGE>

Prepayment Premium in respect thereof. Nothing in this Section 4 shall limit any
other rights the Holder may have under this Note, the Security Documents or the
other Transaction Documents.

         (5)      Vote to Change the Terms of the Notes. The written consent of
the Company and the Holder shall be required in order to affect any amendment,
waiver or other modification of this Note.

         (6)      Lost or Stolen Notes. Upon receipt by the Company of evidence
reasonably satisfactory to the Company of the loss, theft, destruction or
mutilation of this Note, and, in the case of loss, theft or destruction, of an
indemnification undertaking by the Holder to the Company in customary form and
reasonably satisfactory to the Company and, in the case of mutilation, upon
surrender and cancellation of this Note, the Company shall execute and deliver a
new Note of like tenor and date.

         (7)      Remedies, Characterizations, Other Obligations, Breaches and
Injunctive Relief. The remedies provided in this Note shall be cumulative and in
addition to all other remedies available under the Securities Exchange
Agreement, the Security Documents and the other Transaction Documents, at law or
in equity (including a decree of specific performance and/or other injunctive
relief), and no remedy contained herein shall be deemed a waiver of compliance
with the provisions giving rise to such remedy, and nothing herein shall limit
the Holder's right to pursue actual damages for any failure by the Company to
comply with the terms of this Note. The Company covenants to the Holder that
there shall be no characterization concerning this instrument other than as
expressly provided herein. Amounts set forth or provided for herein with respect
to payments and the like (and the computation thereof) shall be the amounts to
be received by the Holder and shall not, except as expressly provided herein, be
subject to any other obligation of the Company (or the performance thereof). The
Company acknowledges that a breach by it of its obligations hereunder will cause
irreparable harm to the Holder and that the remedy at law for any such breach
may be inadequate. The Company therefore agrees that, in the event of any such
breach or threatened breach, the Holder shall be entitled, in addition to all
other available remedies, to an injunction restraining any breach, without the
necessity of showing economic loss and without any bond or other security being
required.

         (8)      Specific Shall Not Limit General; Construction. No specific
provision contained in this Note shall limit or modify any more general
provision contained herein. This Note shall be deemed to be jointly drafted by
the Company and the Buyers pursuant to the Securities Exchange Agreement and
shall not be construed against any person as the drafter hereof.

         (9)      Failure or Indulgence Not Waiver. No failure or delay on the
part of the Holder in the exercise of any power, right or privilege hereunder
shall operate as a waiver thereof, nor shall any single or partial exercise of
any such power, right or privilege preclude other or further exercise thereof or
of any other right, power or privilege.

                                       14
<PAGE>

         (10)     Notice. Whenever notice is required to be given under this
Note, unless otherwise provided herein, such notice shall be given in accordance
with Section 9(f) of the Securities Exchange Agreement.

         (11)     Transfer of this Note. The Holder may assign or transfer some
or all of its rights hereunder, subject to compliance with applicable Securities
Laws (if applicable) and the provisions of Section 2(f) of the Securities
Exchange Agreement without the consent of the Company. Notwithstanding anything
to the contrary contained in this Section 11, each such assignee or transferee,
upon becoming a Holder hereunder, acknowledges that it is bound by the terms and
conditions of Section 5.12 of the Security Agreement and agrees to, promptly
upon the request of the Collateral Agent, deliver to Collateral Agent a written
Joinder to the Security Agreement and other Security Documents.

         (12)     Payment of Collection, Enforcement and Other Costs. Without
limiting the provisions of the Securities Exchange Agreement, the Security
Documents and the other Transaction Documents, if (a) this Note is placed in the
hands of an attorney for collection or enforcement or is collected or enforced
through any legal proceeding; or (b) an attorney is retained to represent the
Holder in any bankruptcy, reorganization, receivership of the Company or other
proceedings affecting Company creditors' rights and involving a claim under this
Note, then the Company shall pay the costs incurred by the Holder for such
collection, enforcement or action, including reasonable attorneys' fees and
disbursements.

         (13)     Cancellation. After all principal and other amounts at any
time owed under this Note have been paid in full in accordance with the terms
hereof, this Note shall automatically be deemed canceled, shall be surrendered
to the Company for cancellation and shall not be reissued.

         (14)     Note Exchangeable for Different Denominations. Subject to
Section 3(d), in the event of an option, mandatory or scheduled payment of less
than all of the Principal pursuant to the terms hereof, the Company shall, upon
the request of Holder and tender of this Note promptly cause to be issued and
delivered to the Holder, a new Note of like tenor representing the remaining
Principal that has not been so repaid. This Note is exchangeable, upon the
surrender hereof by the Holder at the principal office of the Company, for a new
Note or Notes containing the same terms and conditions and representing in the
aggregate the Principal, and each such new Note will represent such portion of
such Principal as is designated by the Holder at the time of such surrender. The
date the Company initially issued this Note shall be the "Issuance Date" hereof
regardless of the number of times a new Note shall be issued.

         (15)     Taxes.
                  -----

                  (a)      Payments Free of Taxes. Any and all payments by or on
account of any obligation of the Company or any of the Included Subsidiaries
under this Note, the Securities Exchange Agreement, the Security Documents or
any other Transaction Document shall be made without any set-off, counterclaim
or deduction and free and clear of and without deduction for any Indemnified
Taxes; provided that if the Company or any of the Included Subsidiaries shall be
required to deduct any Indemnified Taxes from such payments, then (i) the sum
payable shall be increased as necessary so that after making all required
deductions (including deductions applicable to additional sums payable under

                                       15
<PAGE>

this Section 15(a)), the Holder receives an amount equal to the sum it would
have received had no such deductions been made, (ii) the Company or the
applicable Included Subsidiary shall make such deductions and (iii) the Company
or the applicable Included Subsidiary as applicable shall pay the full amount
deducted to the relevant Governmental Authority in accordance with applicable
law.

                  (b)      Indemnification by the Company. The Company shall
indemnify the Holder, within ten (10) days after written demand therefor, for
the full amount of any Indemnified Taxes paid by the Holder, on or with respect
to any payment by or on account of any obligation of the Company or any of the
Included Subsidiaries under the Notes, the Securities Exchange Agreement, the
Security Documents or any of the other Transaction Documents (including
Indemnified Taxes imposed or asserted on or attributable to amounts payable
under this Section 15) and any penalties, interest and reasonable expenses
arising therefrom or with respect thereto, whether or not such Indemnified Taxes
were correctly or legally imposed or asserted by the relevant Governmental
Authority. A certificate of the Holder as to the amount of such payment or
liability under this Section 15 shall be delivered to the Company and shall be
conclusive absent manifest error. In addition, the Company shall promptly pay
the fees, costs and expenses incurred thereby in connection with the engagement
of the Petroleum Engineer and the Qualified Appraiser with respect to the
determination of the PUD, the PDNP, the PDP, the PRV Ratio, the Revenue and the
Financial Covenant Test Failure Amount.

         (16)     Waiver of Notice. To the extent permitted by law, the Company
hereby waives demand, notice, protest and all other demands and notices in
connection with the delivery, acceptance, performance, default or enforcement of
this Note, the Security Documents, the Securities Exchange Agreement and the
other Transaction Documents.

         (17)     Governing Law. This Note shall be construed and enforced in
accordance with, and all questions concerning the construction, validity,
interpretation and performance of this Note shall be governed by, the internal
laws of the State of New York, without giving effect to any choice of law or
conflict of law provision or rule (whether of the State of New York or any other
country or jurisdiction) that would cause the application of the laws of any
jurisdiction or country other than the State of New York. Each party hereby
irrevocably submits to the exclusive jurisdiction of the state and federal
courts sitting in the City of New York, borough of Manhattan, for the
adjudication of any dispute hereunder or in connection herewith or with any
transaction contemplated hereby or discussed herein, and hereby irrevocably
waives, and agrees not to assert in any suit, action or proceeding, any claim
that it is not personally subject to the jurisdiction of any such court, that
such suit, action or proceeding is brought in an inconvenient forum or that the
venue of such suit, action or proceeding is improper. Each party hereby
irrevocably waives personal service of process and consents to process being
served in any such suit, action or proceeding by mailing a copy thereof by
registered or certified U.S. mail, return receipt requested, or by a nationally
recognized overnight delivery service, to such party at the address for such
notices to it under this Note and agrees that such service shall constitute good
and sufficient service of process and notice thereof. Nothing contained herein
shall be deemed to limit in any way any right to serve process in any manner
permitted by law. EACH PARTY HEREBY IRREVOCABLY WAIVES ANY RIGHT IT MAY HAVE,
AND AGREES NOT TO REQUEST, A JURY TRIAL FOR THE ADJUDICATION OF ANY DISPUTE
HEREUNDER OR IN CONNECTION HEREWITH OR ARISING OUT OF THIS NOTE OR ANY
TRANSACTION CONTEMPLATED HEREBY.

                                       16
<PAGE>

         (18)     Further Assurances. The Company shall do and perform, or cause
to be done and performed, all such further acts and things, and shall execute
and deliver all such other agreements, certificates, instruments and documents,
as the Holder may reasonably request in order to carry out the intent and
accomplish the purposes of this Note and the consummation of the transactions
contemplated hereby.

         (19)     Payment Set Aside. To the extent that the Company makes a
payment or payments to the Holder hereunder or the Holder enforces or exercises
its rights hereunder, and such payment or payments or the proceeds of such
enforcement or exercise or any part thereof are subsequently invalidated,
declared to be fraudulent or preferential, set aside, recovered from, disgorged
by or are required to be refunded, repaid or otherwise restored to the Company,
by a trustee, receiver or any other person under any law (including any
Bankruptcy Law, U.S. state or federal law, the laws of any foreign government or
any political subdivision thereof, common law or equitable cause of action),
then to the extent of any such restoration the obligation or part thereof
originally intended to be satisfied shall be revived and continued in full force
and effect as if such payment had not been made or such enforcement or setoff
had not occurred.

         (20)     Interpretative Matters. Unless the context otherwise requires,
(a) all references to Sections, Schedules or Exhibits are to Sections, Schedules
or Exhibits contained in or attached to this Note, (b) words in the singular or
plural include the singular and plural and pronouns stated in either the
masculine, the feminine or neuter gender shall include the masculine, feminine
and neuter and (d) the use of the word "including" in this Note shall be by way
of example rather than limitation.

         (21)     Signatures. In the event that any signature to this Note or
any amendment hereto is delivered by facsimile transmission or by e-mail
delivery of a ".pdf" format data file, such signature shall create a valid and
binding obligation of the party executing (or on whose behalf such signature is
executed) with the same force and effect as if such facsimile or ".pdf"
signature page were an original thereof. Notwithstanding the foregoing, the
Company shall be required to deliver an originally executed Note to the Holder.
At the request of any party each other party shall promptly re-execute an
original form of this Note or any amendment hereto and deliver the same to the
other party. No party hereto shall raise the use of a facsimile machine or
e-mail delivery of a ".pdf" format data file to deliver a signature to this Note
or any amendment hereto or the fact that such signature was transmitted or
communicated through the use of a facsimile machine or e-mail delivery of a
".pdf" format data file as a defense to the formation or enforceability of a
contract and each party hereto forever waives any such defense.

     [ Remainder of Page Intentionally Left Blank; Signature Page Follows ]

                                       17
<PAGE>

         IN WITNESS WHEREOF, the Company has caused this Note to be executed on
its behalf by the undersigned as of the year and date first above written.

                                       SONTERRA RESOURCES, INC., a Delaware
                                       corporation

                                       By: _____________________________________

                                       Name: ___________________________________

                                       Title: __________________________________

<PAGE>

                                    EXHIBIT A

                      Petroleum Engineer Report Guidelines

                                   [Attached]

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