EXHIBIT 10.21

Amendment No. 1
to
Promisssory note

From:

American Exploration Corporation

To:

mainland resources Inc.

THIS AMENDMENT NO. 1 TO PROMISSORY NOTE (the "Amendment")

is made as of December 23, 2010

BETWEEN:

MAINLAND RESOURCES, INC.

, a company existing under the laws of the State of Nevada, USA

("Mainland")

AND:

AMERICAN EXPLORATION CORPORATION

, a company existing under the laws of the State of Nevada, USA

("American Exploration")

WHEREAS

:

(A)     American Exploration (as Borrower) and Mainland (as Lender), entered
into that certain Promissory Note (the "Promissory Note") dated September 27,
2010, whereby American Exploration promised to pay Mainland, or the holder of
the Promissory Note, in accordance with the terms and conditions referenced
therein, the aggregate Principal Sum of U.S.$60,000, together with Interest
payable thereon commencing on the Effective Date of September 27, 2010 at the
rate of twelve percent (12%) per annum, calculated daily and payable in full
monthly during the continuance of any portion of the Principal Sum being
outstanding thereunder prior to maturity, in the manner as set forth in such
Promissory Note;

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(B)     The Promissory Note provides that the Principal Sum, together with all
outstanding Interest thereon, is due and payable by American Exploration to
Mainland on or before 5:00 p.m. (Vancouver, British Columbia, time) on the
"Final Principal Sum Payment Date", which is defined in the Promissory Note to
mean December 31, 2010;

(C)     American Exploration and Mainland wish to amend the terms of the
Promissory Note to extend the Final Principal Sum Payment Date to March 31,
2011;

THIS AMENDMENT WITNESSES

that in consideration of the respective covenants and agreements herein
contained, American Exploration and Mainland covenant and agree as follows:

Certain Definitions

1.     Capitalized terms not otherwise herein defined shall have the meaning
ascribed to them in the Promissory Note.

Termination Date

2.     The Promissory Note is hereby amended to replace "December 31, 2010" with
"March 31, 2011" in the definition of "Final Principal Sum Payment Date".

Amendment

3.     Except as expressly amended hereby, the Promissory Note is in all
respects ratified and confirmed and all the terms, conditions, and provisions
thereof shall remain in full force and effect as of the date hereof.

Effect of Amendment

4.     This Amendment shall form a part of the Promissory Note for all purposes,
and each of American Exploration and Mainland shall be bound hereby. From and
after the execution of this Amendment by the parties hereto, any reference to
the Promissory Note shall be deemed a reference to the Promissory Note as
amended hereby.

Entire Agreement

5.     This Amendment constitutes the entire agreement between the parties
hereto, and supersedes every previous agreement, communication, expectation,
negotiation, representation or understanding, whether oral or written, express
or implied, statutory or otherwise between the parties hereto, with respect to
the subject matter of this Amendment. Nothing in this Section 5 will limit or
restrict the effectiveness and validity of any document with respect to the
subject matter of this Amendment that is executed and delivered
contemporaneously with or pursuant to this Amendment.

Governing Laws

6.     This Amendment shall be governed by and construed in accordance with the
laws of the Province of British Columbia and the laws of Canada applicable
therein and shall be treated in all respects as a British Columbia contract.

Counterparts

7.     This Amendment may be executed in any number of counterparts, in original
form or by facsimile, each of which will together, for all purposes, constitute
one and the same instrument, binding

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on the parties hereto, and each of which will together be deemed to be an
original, notwithstanding that each party hereto is not a signatory to the same
counterpart.

Headings

8.     The descriptive headings of the several Sections of this Amendment were
formulated, used and inserted in this Amendment for convenience only and shall
not be deemed to affect the meaning or construction of any of the provisions
hereof.

THE BALANCE OF THIS PAGE IS INTENTIONALLY LEFT BLANK

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IN WITNESS WHEREOF

this Amendment has been executed by the parties hereto effective as of the day
and year first above written.

MAINLAND RESOURCES, INC.

By: /s/ William D. Thomas"
      Name: William D. Thomas
      Title: Chief Financial Officer

AMERICAN EXPLORATION CORPORATION

By: /s/ Steven Harding"
     Name: Steven Harding
     Title: President and CEO