Fourth Supplemental Indenture to Indenture dated as of August 2, 2004



 Exhibit 4.2.1 

  
 CHESAPEAKE ENERGY CORPORATION 
  
 and 
  
 the Subsidiary Guarantors named herein 
  

  
 7.00% SENIOR NOTES DUE 2014 
  

  
 FOURTH SUPPLEMENTAL INDENTURE 
  
 DATED AS OF JULY 15, 2005 
  

  
 THE BANK OF NEW YORK 
  
 as Trustee 
  

  








 THIS FOURTH SUPPLEMENTAL INDENTURE, dated as of July 15, 2005, is among Chesapeake Energy Corporation, an
Oklahoma corporation (the “Company”), each of the parties identified under the caption “Subsidiary Guarantors” on the signature page hereto (the “Subsidiary Guarantors”) and The Bank of New
York, as Trustee. 
  
 RECITALS 
  
 WHEREAS, the Company, the Subsidiary Guarantors a party thereto and the
Trustee entered into an Indenture, dated as of August 2, 2004, as supplemented prior to the date hereof (the “Indenture”), pursuant to which the Company has originally issued $300,000,000 in principal amount of 7.00% Senior Notes
due 2014 (the “Notes”); and 
  
 WHEREAS, Section
9.01(3) of the Indenture provides that the Company, the Subsidiary Guarantors and the Trustee may amend or supplement the Indenture without notice to or consent of any Holder to reflect the addition of any Subsidiary Guarantor, as provided for in
the Indenture; and 
  
 WHEREAS, the Board of Directors of the
Company has designated Chesapeake Eagle Canada Corp. as a Restricted Subsidiary of the Company and desires to add the entity as a Subsidiary Guarantor under the Indenture; and 
  
 WHEREAS, all acts and things prescribed by the Indenture, by law and by the charter and the bylaws (or comparable
constituent documents) of the Company, of the Subsidiary Guarantors and of the Trustee necessary to make this Fourth Supplemental Indenture a valid instrument legally binding on the Company, the Subsidiary Guarantors and the Trustee, in accordance
with its terms, have been duly done and performed; 
  
 NOW,
THEREFORE, to comply with the provisions of the Indenture and in consideration of the above premises, the Company, the Subsidiary Guarantors and the Trustee covenant and agree for the equal and proportionate benefit of the respective Holders of the
Notes as follows: 
  
 ARTICLE 1 
  
 Section 1.01. This Fourth Supplemental Indenture is supplemental to
the Indenture and does and shall be deemed to form a part of, and shall be construed in connection with and as part of, the Indenture for any and all purposes. 
  

Section 1.02. This Fourth Supplemental Indenture shall become effective immediately upon its execution and delivery by each of the Company, the
Subsidiary Guarantors and the Trustee. 
  

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 ARTICLE 2 
  

Section 2.01. From this date, in accordance with Section 10.03 of the Indenture and by executing this Fourth Supplemental Indenture, Chesapeake
Eagle Canada Corp., a New Brunswick corporation, is subject to the provisions of the Indenture as Subsidiary Guarantor to the extent provided for in Article Ten thereunder. 
  
 ARTICLE 3 
  
 Section 3.01. Except as specifically modified herein, the Indenture and the Notes are in all respects ratified and confirmed (mutatis
mutandis) and shall remain in full force and effect in accordance with their terms with all capitalized terms used herein without definition having the same respective meanings ascribed to them as in the Indenture. 
  
 Section 3.02. Except as otherwise expressly provided herein, no
duties, responsibilities or liabilities are assumed, or shall be construed to be assumed, by the Trustee by reason of this Fourth Supplemental Indenture. This Fourth Supplemental Indenture is executed and accepted by the Trustee subject to all the
terms and conditions set forth in the Indenture with the same force and effect as if those terms and conditions were repeated at length herein and made applicable to the Trustee with respect hereto. 
  
 Section 3.03. The Company hereby notifies the Trustee that Chesapeake
Eagle Canada Corp. has been designated by the Board of Directors of the Company as a Restricted Subsidiary (as that term is defined in the Indenture). 
  
 Section 3.04. THE LAW OF THE STATE OF NEW YORK SHALL GOVERN AND BE USED TO CONSTRUE AND ENFORCE THIS FOURTH SUPPLEMENTAL INDENTURE. 
  
 Section 3.05. The parties may sign any number of copies of this Fourth
Supplemental Indenture. Each signed copy shall be an original, but all of such executed copies together shall represent the same agreement. 
  
 [NEXT PAGE IS SIGNATURE PAGE] 
  

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 IN WITNESS WHEREOF, the parties hereto have caused this Fourth Supplemental Indenture to be duly
executed, all as of the date first written above. 
  

	
	
	 /s/ Aubrey K. McClendon

	 Aubrey K. McClendon

	
	Chief Executive Officer of the Company and of the Subsidiaries listed below:
	
	Corporate Subsidiaries:
	
	 CHESAPEAKE EAGLE CANADA CORP.
 CHESAPEAKE ENERGY LOUISIANA CORPORATION
 CHESAPEAKE PRH CORP.
 CHESAPEAKE SOUTH TEXAS CORP.
 NOMAC DRILLING CORPORATION
 OXLEY PETROLEUM CO.

	
	 CHESAPEAKE OPERATING, INC.,
 On behalf of itself and, as general partner, the following limited partnerships:

	
	 CHESAPEAKE EXPLORATION LIMITED PARTNERSHIP
 CHESAPEAKE LOUISIANA, L.P.
 CHESPEAKE NFW, L.P.
 CHESAPEAKE PERMIAN, L.P.
 CHESAPEAKE SIGMA, L.P.
 CHESAPEAKE-STAGHORN ACQUISITION, L.P.
 CHESAPEAKE ZAPATA, L.P.

	
	 CHESAPEAKE ENERGY MARKETING, INC.,
 On behalf of itself and, as general partner, the following limited partnerships:

	
	 MIDCON COMPRESSION, L.P.

	
	Limited Liability Company Subsidiaries:
	
	 CARMEN ACQUISITION, L.L.C.
 CHESAPEAKE ACQUISITION, L.L.C.
 CHESAPEAKE ENO ACQUISITION, L.L.C.
 CHESAPEAKE EP, L.L.C.
 CHESAPEAKE LAND COMPANY, L.L.C.
 CHESAPEAKE ORC, L.L.C.
 CHESAPEAKE PERMIAN ACQUISITION, L.L.C.
 CHESAPEAKE ROYALTY, L.L.C.



  

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	 GOTHIC PRODUCTION, L.L.C.
 JOHN C. OXLEY, L.L.C.
 MC MINERAL COMPANY, L.L.C.
 MAYFIELD PROCESSING, L.L.C.

	
	 TRUSTEE:

	
	 THE BANK OF NEW YORK, as Trustee

		
	By:	 	 /s/ Steven D. Torgeson

	 Name:
	 	 Steven. D. Torgeson

	 Title:
	 	 Vice President



  

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