UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G/A Under the Securities Exchange Act of 1934 (Amendment No.6)* DAWSON GEOPHYSICAL COMPANY ----------------------------------------------------------------- (Name of Issuer) Common Stock ----------------------------------------------------------------- (Title of Class of Securities) 239359102 -------------------- (CUSIP Number) December 31, 2004 ---------------------------------------------------------------- (Date of Event Which Requires Filing of this Statement) Check the appropriate box to designate the rule pursuant to which this Schedule is filed: / X / Rule 13d-1(b) / / Rule 13d-1(c) / / Rule 13d-1(d) *The remainder of this cover page shall be filled out for a reporting person's initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter the disclosures provided in a prior cover page. The information required in the remainder of this cover page shall not be deemed to be "filed" for the purpose of Section 18 of the Securities Exchange Act of 1934 ("Act") or otherwise subject to the liabilities of the section of the Act but shall be subject to all other provisions of the Act (however, see the Notes). SCHEDULE 13G/A CUSIP NO. 239359102 1. Names of Reporting Persons. I.R.S. Identification Nos. of above persons (entities only). Quaker Capital Management Corporation ------------------------------------------------------------------------ 2. Check the Appropriate Box if a Member of a Group (a) ----- (b) X ----- 3. SEC Use Only --------------------------------------------------------- 4. Citizenship or Place of Organization Pennsylvania --------------- Number of 5. Sole Voting Power 0 Shares --------------- Beneficially 6. Shared Voting Power 0 Owned by --------------- Each Reporting 7. Sole Dispositive Power 0 Person With: --------------- 8. Shared Dispositive Power 0 --------------- 9. Aggregate Amount Beneficially Owned by Each Reporting Person 0 --------- 10. Check if the Aggregate Amount in Row (9) Excludes Certain Shares -------- 11. Percent of Class Represented by Amount in Row (9) 0% --------- 12. Type of Reporting Person IA -------------- Page 2 of 6 Pages SCHEDULE 13G/A CUSIP NO. 239359102 Item 1. (a) Name of Issuer Dawson Geophysical Company -------------------------------------------------------------- (b) Address of Issuer's Principal Executive Offices 508 West Wall, Suite 800, Midland, Texas 79701 -------------------------------------------------------------- Item 2. (a) Name of Persons Filing Quaker Capital Management Corporation -------------------------------------------------------------- (b) Address of Principal Business Office or, if none, Residence 401 Wood Street, Suite 1300, Pittsburgh, PA 15222 -------------------------------------------------------------- (c) Citizenship Pennsylvania, USA -------------------------------------------------------------- (d) Title of Class of Securities Common Stock -------------------------------------------------------------- (e) CUSIP Number 239359102 -------------------------------------------------------------- Page 3 of 6 Pages SCHEDULE 13G/A CUSIP NO. 239359102 Item 3. If this statement is filed pursuant to ss.ss.240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a: (a) / / Broker of dealer registered under section 15 of the Act; (b) / / Bank as defined in section 3(a)(6) of the Act; (c) / / Insurance company as defined in section 3(a)(19) of the Act; (d) / / Investment company registered under section 8 of the Investment Company Act of 1940; (e) / X / An investment adviser in accordance with ss.240.13d- 1(b) (l)(ii)(E); (f) / / An employee benefit plan or endowment fund in ccordance with ss.240.13d-1(b)(1)(ii)(F); (g) / / A parent holding company or control person in accordance with ss.240.13d-1(b)(1)(ii)(G); (h) / / A savings association as defined in Section 3(b) of the Federal Deposit Insurance Act; (i) / / A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the Investment Company Act of 1940; (j) / / Group, in accordance with ss.240.13d-1((b)(l)(ii)(J) Item 4. Ownership --------- (a) The Reporting Person no longer beneficially owns any shares of Common Stock of the Issuer. (b) The shares covered by this report represent 0% of the Common Stock of the Issuer. (c) The Reporting Person does not have voting or dispositive power over any shares of Common Stock of the Issuer. Page 4 of 6 Pages SCHEDULE 13G/A CUSIP NO. 239359102 Item 5. Ownership of Five Percent or Less of a Class If this statement is being filed to report the fact that as of the date hereof, the reporting person has ceased to be the beneficial owner of more than five percent of the class of securities, check the following: X ---------- Item 6. Ownership of More than Five Percent on Behalf of Another Person Not applicable. Item 7. Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company Not applicable. Item 8. Identification and Classification of Members of the Group Not applicable. Item 9. Notice of Dissolution of Group Not applicable. Item 10. Certification By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were acquired and are held in the ordinary course of business and were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect. Page 5 of 6 Pages SCHEDULE 13G/A CUSIP NO. 239359102 SIGNATURE After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct. QUAKER CAPITAL MANAGEMENT CORPORATION February 9, 2005 ---------------------------------- Date /s/ Mark G. Schoeppner ---------------------------------- Signature Mark G. Schoeppner, President ---------------------------------- Name/Title Page 6 og 6 Pages