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UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 10-K/A

Amendment No. 1

x      ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the fiscal year ended December 31, 2009

o         TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the transition period from                  to                   .

Commission File Number 01-14908

TGC INDUSTRIES, INC.

(Exact name of registrant as specified in its charter)

Registrant’s telephone number, including area code:  (972) 881-1099

Securities registered pursuant to Section 12(b) of the Act:

Securities registered pursuant to Section 12(g) of the Act: None

Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act.  Yes o    No x

Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the Act.  Yes o    No x

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15 (d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days.  Yes  x    No  o

Indicate by check mark whether the registrant has submitted electronically and posted on its corporate Website, if any, every Interactive Data File required to be submitted and posted pursuant to Rule 405 of Regulation S-T (Section 232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit and post such files).  Yes o    No o

Indicate by check mark if disclosure of delinquent filers pursuant to Item 405 of Regulation S-K (229.405) is not contained herein, and will not be contained, to the best of Registrant’s knowledge, in definitive proxy or information statements incorporated by reference in Part III of this Form 10-K or any amendment to this Form 10-K.  x

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, or a smaller reporting company.  See the definitions of “large accelerated filer,” “accelerated filer” and “smaller reporting company” in Rule 12b-2 of the Exchange Act.

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act).  Yes o    No x

The aggregate market value of the voting and non-voting common equity held by non-affiliates computed by reference to the price at which the common equity was last sold as of the last business day of the Registrant’s most recently completed second  fiscal quarter was $64,577,846.

Number of shares of Common Stock outstanding as of February 26, 2010:  18,285,288

Documents incorporated by reference

Listed below are documents, parts of which are incorporated herein by reference, and the part of this report into which the document is incorporated:

Proxy statement for the 2010 annual meeting of shareholders — Part III

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Part I

EXPLANATORY NOTE

The purpose of this Form 10-K/A is to amend Part II, Item 8 and Item 9A of the TGC Industries, Inc. Form 10-K (the “Original Filing”) for the fiscal year ended December 31, 2009, as filed with the Securities and Exchange Commission on March 16, 2010, to include a signed copy of the Report of Independent Registered Public Accounting Firm (the “Report”).  The Original Filing inadvertently included an unsigned copy of the Report.  Except for providing a signed copy of the Report, this Form 10-K/A does not reflect any events that occurred after the filing of the Original Filing nor does it modify, amend or update any disclosures contained in the Original Filing to reflect any subsequent events.

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PART II

ITEM 8. FINANCIAL STATEMENTS AND SUPPLEMENTARY DATA.

Consolidated Financial Statements

December 31, 2009, 2008, and 2007

CONTENTS

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Report of Independent Registered Public Accounting Firm

Board of Directors and Shareholders

TGC Industries, Inc. and Subsidiary

We have audited the accompanying consolidated balance sheets of TGC Industries, Inc. and Subsidiary (“the Company”) as of December 31, 2009 and 2008, and the related consolidated statements of income, shareholders’ equity, and cash flows for each of the three years in the period ended December 31, 2009.  We also have audited the Company’s internal control over financial reporting as of December 31, 2009, based on criteria established in Internal Control—Integrated Framework issued by the Committee of Sponsoring Organizations of the Treadway Commission (COSO). The Company’s management is responsible for these consolidated financial statements, for maintaining effective internal control over financial reporting, and for its assessment of the effectiveness of internal control over financial reporting, included in the accompanying Management’s Report on Internal Control over Financial Reporting. Our responsibility is to express an opinion on these consolidated financial statements and an opinion on the Company’s internal control over financial reporting based on our audits.

We conducted our audits in accordance with the standards of the Public Company Accounting Oversight Board (United States). Those standards require that we plan and perform the audits to obtain reasonable assurance about whether the consolidated financial statements are free of material misstatement and whether effective internal control over financial reporting was maintained in all material respects. Our audits of the consolidated financial statements included examining, on a test basis, evidence supporting the amounts and disclosures in the consolidated financial statements, assessing the accounting principles used and significant estimates made by management, and evaluating the overall financial statement presentation. Our audit of internal control over financial reporting included obtaining an understanding of internal control over financial reporting, assessing the risk that a material weakness exists, and testing and evaluating the design and operating effectiveness of internal control based on the assessed risk. Our audits also included performing such other procedures as we considered necessary in the circumstances. We believe that our audits provide a reasonable basis for our opinions.

A Company’s internal control over financial reporting is a process designed to provide reasonable assurance regarding the reliability of financial reporting and the preparation of consolidated financial statements for external purposes in accordance with generally accepted accounting principles. A Company’s internal control over financial reporting includes those policies and procedures that (1) pertain to the maintenance of records that, in reasonable detail, accurately and fairly reflect the transactions and dispositions of the assets of the Company; (2) provide reasonable assurance that transactions are recorded as necessary to permit preparation of consolidated financial statements in accordance with generally accepted accounting principles, and that receipts and expenditures of the Company are being made only in accordance with authorizations of management and directors of the Company; and (3) provide reasonable assurance regarding prevention or timely detection of unauthorized acquisition, use, or disposition of the Company’s assets that could have a material effect on the consolidated financial statements.

Because of its inherent limitations, internal control over financial reporting may not prevent or detect misstatements. Also, projections of any evaluation of effectiveness to future periods are subject to the risk that controls may become inadequate because of changes in conditions, or that the degree of compliance with the policies or procedures may deteriorate.

In our opinion, the consolidated financial statements referred to above present fairly, in all material respects, the financial position of TGC Industries, Inc. and Subsidiary as of December 31, 2009 and 2008, and the results of its operations and its cash flows for each of the years in the three year period ended December 31, 2009 in conformity with accounting principles generally accepted in the United States of America. Also in our opinion, the Company maintained, in all material respects, effective internal control over financial reporting as of December 31, 2009, based on criteria established in Internal Control—Integrated Framework issued by the COSO.

/s/ Lane Gorman Trubitt, L.L.P.

Dallas, Texas

March 16, 2010

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TGC Industries, Inc.

CONSOLIDATED BALANCE SHEETS

December 31,

The accompanying notes are an integral part of these consolidated financial statements

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TGC Industries, Inc.

CONSOLIDATED BALANCE SHEETS — Continued

December 31,

The accompanying notes are an integral part of these consolidated financial statements

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TGC Industries, Inc.

CONSOLIDATED STATEMENTS OF EARNINGS

Years Ended December 31,

The accompanying notes are an integral part of these consolidated financial statements

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TGC Industries, Inc.

CONSOLIDATED STATEMENTS OF SHAREHOLDERS’ EQUITY

The accompanying notes are an integral part of these consolidated financial statements

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TGC Industries, Inc.

CONSOLIDATED STATEMENTS OF CASH FLOWS

Years Ended December 31,

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TGC Industries, Inc.

CONSOLIDATED STATEMENTS OF CASH FLOWS - CONTINUED

Years Ended December 31,

The accompanying notes are an integral part of these consolidated financial statements

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TGC Industries, Inc.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

December 31, 2009, 2008, and 2007

NOTE A - NATURE OF OPERATIONS

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

Management has evaluated subsequent events through March 16, 2010, which is the date of the consolidated financial statements were available to be issued.

NOTE B - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

Principles of Consolidation

The Consolidated Financial Statements include the accounts of TGC Industries, Inc. and its wholly-owned subsidiary, Eagle Canada, Inc.  We have eliminated all significant intercompany accounts and transactions.

Business Combinations

We record acquisitions using the purchase method of accounting and, accordingly, have included the results of operations of acquired businesses in our consolidated results from the date of each acquisition.  We allocate the purchase price of our acquisitions to the tangible assets, liabilities, and intangible assets acquired based on their estimated fair values. The excess purchase price over those fair values is recorded as goodwill. The fair value assigned to assets acquired is based on valuations provided by independent consultants and using management’s estimates and assumptions.

Foreign Currency

The functional currency of the Company’s international subsidiary is the local currency.  Local currency assets and liabilities are translated at the rates of exchange on the balance sheet date, and local currency revenues and expenses are translated at average rates of exchange during the period.  The resulting translation adjustments are recorded directly into a separate component of stockholders’ equity and represents the only component of accumulated other comprehensive income.

Cash Equivalents

The Company considers all highly liquid investments with original maturity dates of three months or less to be cash equivalents. The Company maintains its accounts at financial institutions located in Texas and Alberta, Canada.  The Texas bank accounts are insured by the Federal Deposit Insurance Corporation up to $250,000.  The Alberta bank accounts are insured by the Canadian Depository Insurance Corporation up to $100,000 Canadian dollars.

Trade Accounts Receivable

Trade accounts receivable are recorded in accordance with terms and amounts as specified in the related contracts on an ongoing basis. The Company evaluates the collectibility of accounts receivable on a specific account basis using a combination of factors including the age of the outstanding balances, evaluation of the customer’s financial condition, and discussions with relevant Company personnel and with the customers directly. An allowance for doubtful accounts or direct write-off is recorded when it is determined that the receivable may not be collected, depending on the facts known and the probability of collection of the outstanding amount.

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TGC Industries, Inc.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

December 31, 2009, 2008, and 2007

NOTE B - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES — CONTINUED

Property and Equipment

Property and equipment are stated at cost. Depreciation and amortization are provided using the straight-line method over the estimated useful lives of the individual assets ranging from 1 to 7 years.  The depreciation expense on assets acquired under capital leases is included with depreciation expense on owned assets.  Expenditures for major renewals and betterments that extend the useful lives of property and equipment are capitalized.  Expenditures for maintenance and repairs are charged to expense as incurred.

Long-Lived Assets

Long-lived assets held and used by the Company are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. For the purposes of evaluating the recoverability of long-lived assets, the recoverability test is performed using undiscounted cash flows estimated to be generated by those assets.  No impairment charge was necessary at December 31, 2009, 2008, and 2007.

Income Taxes

The Company utilizes the liability method of accounting for income taxes.  Under the liability method, deferred income tax assets and liabilities are provided based on the difference between the financial statement and tax bases of assets and liabilities measured by the currently enacted tax rates in effect for the years in which these differences are expected to reverse.  Deferred tax expense or benefit is the result of changes in deferred tax assets and liabilities.  An allowance against deferred tax assets is recorded in whole or in part when it is more likely than not that such tax benefits will not be realized.

Effective January 1, 2007, the Company adopted certain amendments of Topic No. 740 (“Topic 740”) which clarifies the accounting for income tax positions.  Topic 740 prescribes a recognition threshold and measurement attribute for the financial statement recognition and measurement of a tax position taken or expected to be taken in a tax return.  Under Topic 740, the Company recognizes in its financial statements the impact of a tax position if that position is “more likely than not” to be sustained on audit based on the technical merits of the position.  Topic 740 also provides guidance on derecognition, classification, interest and penalties, accounting in interim periods, and disclosure.  Interest and penalties related to unrecognized tax benefits are recorded as income tax expense.  See Note I for further information.

Revenue Recognition

Seismic Surveys

The Company provides seismic data acquisition survey services to its customers under general service agreements which define certain obligations for the Company and for its customers.  A supplemental agreement setting forth the terms of a specific project, which may be cancelled by either party upon 30 days advance written notice, is entered into for every project.  These supplemental agreements are either “turnkey” agreements providing for a fixed fee to be paid for each unit of seismic data acquired or “term” agreements providing for a fixed hourly, daily, or monthly fee during the term of the project.  The duration of these projects will vary from a few days to several months.  The Company recognizes revenue when services are performed under both types of agreements.  Services are defined as the commencement of data acquisition.  Under turnkey agreements, the total number of units of seismic data to be gathered is set forth in the agreement and revenue is recognized as services are performed on a per unit of seismic data acquired rate.  Under term agreements, revenue is recognized as services are performed based on the time worked rate provided in the term agreement.  Under both turnkey and term agreements, cost of earned revenue is recognized by multiplying total estimated agreement cost by the percentage-of-completion of the agreement.  The excess of that amount over the cost of earned revenue reported in prior periods is recognized as cost of earned revenue for the period.  Agreements are not segmented nor combined for purposes of calculating percentage of