SECURITIES AND EXCHANGE COMMISSION

Washington, D.C.  20549

FORM 8-K

CURRENT REPORT

PURSUANT TO SECTION 13 OR 15(d) OF THE

SECURITIES EXCHANGE ACT OF 1934

DATE OF REPORT (DATE OF EARLIEST EVENT REPORTED):  September 2, 2011

TGC INDUSTRIES, INC.

(Exact name of registrant as specified in its charter)

101 E. Park Blvd., Suite 955

Plano, TX 75074

(Address of principal executive offices) (Zip Code)

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

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (see General Instruction A.2. below):

x          Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

o            Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

o            Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

o            Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Item 8.01.                                          Other Events.

On September 6, 2011, TGC Industries, Inc. (“TGC”) and Dawson Geophysical Company (“Dawson”) issued a joint press release announcing that the Antitrust Division of the United States Department of Justice has closed its investigation without taking any action and that early termination of the waiting period under the Hart-Scott-Rodino Antitrust Improvements Act of 1976, as amended (the “HSR Act”), has been granted in connection with Dawson’s previously announced proposed acquisition of TGC.  Accordingly, the condition to the proposed acquisition of TGC relating to the expiration or termination of the HSR Act waiting period has been satisfied.

A copy of the joint press release is included herein as Exhibit 99.1 and is incorporated by reference herein.

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Important Information For Investors and Shareholders

This report does not constitute an offer to sell or the solicitation of an offer to buy any securities or a solicitation of any vote or approval.  Subject to the terms of the Amendment, the transactions contemplated by the Merger Agreement between TGC and Dawson, including the proposed Merger and the proposed issuance of Dawson common stock in the Merger, will, as applicable, be submitted to the shareholders of TGC and Dawson for their consideration.  Dawson has filed with the Securities and Exchange Commission (“SEC”) Amendment No. 3 to its registration statement on Form S-4 (commission file number 333-174843) that includes a preliminary Proxy Statement/Prospectus regarding the proposed Merger.  After the registration statement has been declared effective by the SEC and subject to the terms of the Amendment, Dawson and TGC will mail the definitive Proxy Statement/Prospectus to their respective shareholders. Dawson and TGC also plan to file other documents with the SEC regarding the proposed transaction. INVESTORS AND SECURITY HOLDERS OF TGC AND DAWSON ARE URGED TO READ THE PROXY STATEMENT/PROSPECTUS (INCLUDING ALL AMENDMENTS AND SUPPLEMENTS THERETO) AND OTHER RELEVANT DOCUMENTS FILED WITH THE SEC CAREFULLY AND IN THEIR ENTIRETY AS THEY BECOME AVAILABLE BECAUSE THEY WILL CONTAIN IMPORTANT INFORMATION ABOUT THE PROPOSED TRANSACTION.  Investors and shareholders may currently obtain free copies of the Proxy Statement/Prospectus filed on June 10, 2011 and amended on July 20, 2011, August 8, 2011 and August 29, 2011, and will be able to obtain free copies of any further amendments to the Proxy Statement/Prospectus as well as other documents containing important information about TGC and Dawson, through the website maintained by the SEC at www.sec.gov. TGC and Dawson make available free of charge at www.tgcseismic.com and www.dawson3d.com, respectively (in the “Investor Relations” section), copies of materials they file with, or furnish to, the SEC, or investors and shareholders may contact TGC at (972) 881-1099 or Dawson at (432) 684-3000 to receive copies of documents that each company files with or furnishes to the SEC.

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Participants in the Proxy Solicitation

TGC, Dawson, and certain of their respective directors and officers may be deemed to be participants in the solicitation of proxies from the shareholders of TGC and Dawson in connection with the proposed transactions.  Information about the directors and officers of TGC is set forth in its Amendment No. 1 to Annual Report on Form 10-K/A, which was filed with the SEC on April 15, 2011.  Information about the directors and officers of Dawson is set forth in its proxy statement for its 2011 annual meeting of shareholders, which was filed with the SEC on December 7, 2010. These documents can be obtained free of charge from the sources indicated above. Other information regarding the participants in the proxy solicitation and a description of their direct and indirect interests, by security holdings or otherwise, is contained in the Proxy Statement/Prospectus and other relevant materials filed with the SEC.

Item 9.01.                                          Financial Statements and Exhibits.

(d)                                  Exhibits

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SIGNATURES

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

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INDEX TO EXHIBITS

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Exhibit 99.1

NEWS RELEASE

Dawson Geophysical Company

508 West Wall, Suite 800

Midland, TX 79701

DAWSON GEOPHYSICAL AND TGC INDUSTRIES
ANNOUNCE CLOSING OF THE DOJ INVESTIGATION AND EARLY TERMINATION OF HART-SCOTT-RODINO WAITING PERIOD

MIDLAND, Texas, September 6, 2011/PR Newswire/ — Dawson Geophysical Company (Dawson) (NASDAQ: DWSN) and TGC Industries, Inc. (TGC) (NASDAQ: TGE) today announced that the Antitrust Division of the United States Department of Justice has closed its investigation without taking any action and that early termination of the waiting period under the Hart-Scott-Rodino Antitrust Improvements Act of 1976, as amended (HSR Act), has been granted, in connection with Dawson’s previously announced proposed acquisition of TGC.  Accordingly, the condition to the proposed acquisition of TGC relating to the expiration or termination of the HSR Act waiting period has been satisfied.

Stephen Jumper, President and Chief Executive Officer of Dawson, said: “We are pleased to have completed this important milestone in the approval process for the merger.  We expect to complete our SEC review and to commence mailing of a joint proxy statement to our respective shareholders.  We look forward to holding our special meeting and, if we receive a favorable vote, eventually welcoming the shareholders of TGC as shareholders of Dawson.”

The acquisition remains subject to certain other closing conditions, including the approval of each of Dawson’s and TGC’s shareholders.

About Dawson

Dawson Geophysical Company is the leading provider of U.S. onshore seismic data acquisition services as measured by the number of active data acquisition crews. Founded in 1952, Dawson acquires and processes 2-D, 3-D and multi-component seismic data solely for its clients, ranging from major oil and gas companies to independent oil and gas operators as well as providers of multi-client data libraries.

About TGC Industries

TGC Industries, Inc., based in Plano, Texas, is a provider of seismic data acquisition services with operations throughout the continental United States and Canada.  TGC has branch offices in Houston, Midland, Oklahoma City and Calgary.

Cautionary Statement Regarding Forward-Looking Statements

In accordance with the Safe Harbor provisions of the Private Securities Litigation Reform Act of 1995, Dawson and TGC caution that statements in this press release which are forward-looking and which provide other than historical information involve risks and uncertainties that may materially affect Dawson’s or TGC’s actual results of operations. These risks include but are not limited to the volatility of oil and natural gas prices, dependence upon energy industry spending, disruptions in the global economy, industry competition, delays, reductions or cancellations of service contracts, high fixed costs of operations, external factors affecting Dawson’s or TGC’s crews such as weather interruptions and inability to obtain land access rights of way, whether either company enters into turnkey or term contracts, crew productivity, limited number of customers, credit risk related to Dawson’s or TGC’s customers, the availability of capital resources, operational disruptions, the ability to obtain all necessary approvals for the merger and the possibility that the shareholder meetings may not be held pursuant to the terms of the merger agreement, as amended.  A discussion of these and other factors, including risks and uncertainties with respect to Dawson is set forth in Dawson’s Form 10-K for the fiscal year ended September 30, 2010 and Dawson’s Form 10-Qs for the three months ended March 31, and June 30, 2011 and with respect to TGC, is set forth in TGC’s Form 10-K for the fiscal year ended December 31, 2010 and TGC’s Form 10-Qs for the three months ended March 31, and June 30, 2011.  Dawson and TGC disclaim any intention or obligation to revise any forward-looking statements, whether as a result of new information, future events or otherwise.

Important Information For Investors and Shareholders

This communication does not constitute an offer to sell or the solicitation of an offer to buy any securities or a solicitation of any vote or approval. Subject to the terms of the merger agreement between Dawson and TGC, as amended, the transactions contemplated by the merger agreement, including the proposed merger and the proposed issuance of Dawson common stock in the merger, will, as applicable, be submitted to the shareholders of Dawson and TGC for their consideration.  Dawson filed with the Securities and Exchange Commission (“SEC”) a registration statement on Form S-4 that included a joint proxy statement of Dawson and TGC that also constitutes a prospectus of Dawson.  After the registration statement has been declared effective and subject to the terms of the merger agreement, Dawson and TGC will mail the joint proxy statement/prospectus to their respective shareholders.  Dawson and TGC also plan to file other documents with the SEC regarding the proposed transaction. INVESTORS AND SECURITY HOLDERS OF DAWSON AND TGC ARE URGED TO READ THE JOINT PROXY STATEMENT/PROSPECTUS AND OTHER RELEVANT DOCUMENTS FILED WITH THE SEC CAREFULLY AND IN THEIR ENTIRETY AS THEY BECOME AVAILABLE BECAUSE THEY WILL CONTAIN IMPORTANT INFORMATION ABOUT THE PROPOSED TRANSACTION.  Investors and shareholders may currently obtain free copies of the joint proxy statement/prospectus filed on June 10, 2011 and amended on July 20, 2011, August 8, 2011 and August 29, 2011, and will be able to obtain free copies of any further amendments to the joint proxy statement/prospectus as well as other documents containing important information about Dawson and TGC filed with the SEC, through the website maintained by the SEC at www.sec.gov.  Dawson and TGC make available free of charge at www.dawson3d.com and www.tgcseismic.com, respectively (in the “Investor Relations” section), copies of materials they file with, or furnish to, the SEC, or investors and shareholders

may contact Dawson at (432) 684-3000 or TGC at (972) 881-1099 to receive copies of documents that each company files with or furnishes to the SEC.

Participants in the Proxy Solicitation

Dawson, TGC, and certain of their respective directors and officers may be deemed to be participants in the solicitation of proxies from the shareholders of Dawson and TGC in connection with the proposed transactions. Information about the directors and officers of Dawson is set forth in its proxy statement for its 2011 annual meeting of shareholders, which was filed with the SEC on December 7, 2010. Information about the directors and officers of TGC is set forth in its Amendment No. 1 to Annual Report on Form 10-K/A, which was filed with the SEC on April 15, 2011. These documents can be obtained free of charge from the sources indicated above. Other information regarding the participants in the proxy solicitation and a description of their direct and indirect interests, by security holdings or otherwise, is contained in the joint proxy statement/prospectus and other relevant materials to be filed with the SEC when they become available.

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