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                                                                    EXHIBIT 4.12

                              CERTIFICATE OF TRUST
                                       OF
                           MARATHON FINANCING TRUST II

          THIS CERTIFICATE OF TRUST of Marathon Financing Trust II (the
"TRUST"), dated as of August 29, 2002, is being duly executed and filed by the
undersigned, as trustees, to form a business trust under the Delaware Business
Trust Act (12 DEL. CODE Section 3801 ET SEQ.).

          1.   NAME. The name of the business trust being formed hereby is
"Marathon Financing Trust II."

          2.   DELAWARE TRUSTEE. The name and business address of the trustee of
the Trust with a principal place of business in the State of Delaware are The
Bank of New York (Delaware), 700 White Clay Center, Route 273, Newark, Delaware
19711.

          3.   EFFECTIVE DATE. This Certificate of Trust shall be effective at
the time of its filing with the Secretary of State of the State of Delaware.

          4.   COUNTERPARTS. This Certificate of Trust may be executed in one or
more counterparts.

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          IN WITNESS WHEREOF, the undersigned, being all of the trustees of the
Trust at the time of filing this Certificate of Trust, have executed this
Certificate of Trust as of the date first above written.

                                         THE BANK OF NEW YORK (DELAWARE),
                                         not in its individual capacity,
                                         but solely as Delaware Trustee

                                         By: /s/ JAMES LONGSHAW
                                             -----------------------------------
                                             Name: James Longshaw
                                             Title: Senior Vice President


                                         THE BANK OF NEW YORK,
                                         not in its individual capacity,
                                         but solely as Property Trustee

                                         By: /s/ REMO J. REALE
                                             -----------------------------------
                                             Name: Remo J. Reale
                                             Title: Vice President


                                         P.C. REINBOLT,
                                         not in his individual capacity,
                                         but solely as Regular Trustee

                                         /s/ P.C. REINBOLT
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