EXHIBIT 4.17


                   FOURTH SUPPLEMENTAL SENIOR NOTE INDENTURE

         FOURTH SUPPLEMENTAL SENIOR NOTE INDENTURE (this "SUPPLEMENTAL SENIOR
NOTE INDENTURE"), dated as of February 16, 2000 among Peabody Natural Gas, LLC,
a Delaware limited liability company (the "GUARANTEEING SUBSIDIARY"), a
subsidiary of Peabody Holding Company, Inc. (or its permitted successor), a New
York corporation (the "COMPANY") the Company, the other Senior Note Guarantors
(as defined in the Senior Note Indenture referred to herein) and State Street
Bank and Trust Company, as Senior Note Trustee under the Senior Note Indenture
referred to below (the "SENIOR NOTE TRUSTEE").

         WHEREAS, the Company has heretofore executed and delivered to the
Senior Note Trustee a Senior Note Indenture (the "SENIOR NOTE INDENTURE"), dated
as of May 18, 1998 providing for the issuance of an aggregate principal amount
of up to $550.0 million of 8-7/8% Senior Notes due 2008 (the "SENIOR NOTES")

         WHEREAS, the Senior Note Indenture provides that under certain
circumstances the Guaranteeing Subsidiary shall execute and deliver to the
Senior Note Trustee a supplemental Senior Note Indenture pursuant to which the
Guaranteeing Subsidiary shall unconditionally guarantee all of the Company's
Obligations under the Senior Notes and the Senior Note Indenture on the terms
and conditions set forth herein (the "SENIOR SUBSIDIARY GUARANTEE"); and

         WHEREAS, pursuant to Section 9.01 of the Senior Note Indenture, the
Senior Note Trustee is authorized to execute and deliver this Supplemental
Senior Note Indenture.

         NOW THEREFORE, in consideration of the foregoing and for other good and
valuable consideration, the receipt of which is hereby acknowledged, the
Guaranteeing Subsidiary and the Senior Note Trustee mutually covenant and agree
for the equal and ratable benefit of the Holders of the Senior Notes as follows:

         1. CAPITALIZED TERMS. Capitalized terms used herein without definition
shall have the meanings assigned to them in the Note Indenture.

         2. AGREEMENT TO GUARANTEE. The Guaranteeing Subsidiary hereby agrees as
follows:

                  (a) Along with all Senior Note Guarantors named in the Senior
         Note Indenture, to jointly and severally Guarantee to each Holder of a
         Senior Note authenticated and delivered by the Senior Note Trustee and
         to the Senior Note Trustee and its successors and assigns, of the
         validity and enforceability of the Senior Note Indenture the Senior
         Notes or the obligations or the Company hereunder or thereunder that:

                      (i) the principal of and interest on the Senior Notes will
                      be promptly paid in full when due, whether at maturity, by
                      acceleration, redemption or otherwise, and interest on the
                      overdue principal and interest on the Senior Notes, if
                      any, if lawful, and all other obligations of the Company
                      to the Holders or the Senior



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                      Note Trustee hereunder or thereunder will be promptly paid
                      in full or performed all in accordance with the terms
                      hereof and thereof, and

                      (ii) in case of any extension of time of payment or
                      renewal of any Senior Notes or any of such other
                      obligations, that same will be promptly paid in full when
                      due or performed in accordance with the terms of the
                      extension or renewal, whether at stated maturity, by
                      acceleration or otherwise. Failing payment when due of any
                      amount so guaranteed or any performance so guaranteed for
                      whatever reason, the Senior Note Guarantors shall be
                      jointly and severally obligated to pay the same
                      immediately.

                  (b) The obligations hereunder shall be unconditional,
         irrespective of the validity, regularity or enforceability of the
         Senior Notes or the Senior Note Indenture, the absence of any action to
         enforce the same, any waiver or consent by any Holder of the Senior
         Notes with respect to any provisions hereof or thereof, the recovery of
         any judgment against the Company, any action to enforce the same or any
         other circumstance which might otherwise constitute a legal or
         equitable discharge or defense of a Senior Note Guarantor.

                  (c) The following is hereby waived: diligence presentment,
         demand of payment, filing of claims with a court in the event of
         insolvency or bankruptcy of the Company, any right to require a
         proceeding first against the Company, protest, notice and all demands
         whatsoever.

                  (d) This Senior Subsidiary Guarantee shall not be discharged
         except by complete performance of the obligations contained in the
         Senior Notes and the Senior Note Indenture.

                  (e) If any Holder or the Senior Note Trustee is required by
         any court or otherwise to return to the Company, the Senior Note
         Guarantors, or any custodian, Senior Note Trustee, liquidator or other
         similar official acting in relation to either the Company or the Senior
         Note Guarantors, any amount paid by either to the Senior Note Trustee
         or such Holder, this Senior Subsidiary Guarantee, to the extent
         theretofore discharged, shall be reinstated in full force and effect.

                  (f) The Guaranteeing Subsidiary shall not be entitled to any
         right of subrogation in relation to the Holders in respect of any
         obligations guaranteed hereby until payment in full of all obligations
         guaranteed hereby.

                  (g) As between the Senior Note Guarantors, on the one hand,
         and the Holders and the Senior Note Trustee, on the other hand, (x) the
         maturity of the obligations guaranteed hereby may be accelerated as
         provided in Article 6 of the Senior Note Indenture for the purposes of
         this Senior Subsidiary Guarantee, notwithstanding any stay, injunction
         or other prohibitions preventing such acceleration in respect of the
         obligations guaranteed hereby, and (y) in the event any declaration of
         accelaration of such obligations as provided in Article 6 of the Senior
         Note Indenture, such obligations (whether or not due and payable) shall
         forthwith


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         become due and payable by the Senior Note Guarantors for the purpose of
         this Senior Subsidiary Guarantee.

                  (h) The Senior Note Guarantors shall have the right to seek
         contribution from any non-paying Senior Note Guarantor so long as the
         exercise of such right does not impair the rights of the Holders under
         the Senior Subsidiary Guarantee.

                  (i) Pursuant to Section 10.04 of the Senior Note Indenture,
         after giving effect to any maximum amount and any other contingent and
         fixed liabilities that are relevant under any applicable Bankruptcy or
         fraudulent conveyance laws, and after giving effect to any collections
         from, rights to receive contribution from or payments made by or on
         behalf of any other Senior Note Guarantor in respect of the obligations
         of such other Senior Note Guarantor under Article 10 of the Senior Note
         Indenture shall result in the obligations of such Senior Note Guarantor
         under its Senior Subsidiary Guarantee not constituting a fraudulent
         transfer or conveyance.

         3. EXECUTION AND DELIVERY. Each Guaranteeing Subsidiary agrees that the
Senior Subsidiary Guarantees shall remain in full force and effect
notwithstanding any failure to endorse on each Senior Note a notation of such
Senior Subsidiary Guarantee.

         4. GUARANTEEING SUBSIDIARY MAY CONSOLIDATE, ETC. ON CERTAIN TERMS

                  (a) The Guaranteeing Subsidiary may not consolidate with or
         merge with or into (whether or not such Senior Note Guarantor is the
         surviving Person) another corporation, Person or entity whether or not
         affiliated with such Senior Note Guarantor unless:

                      (i) subject to Section 10.04 of the Senior Note Indenture,
                      the Person formed by or surviving any such consolidation
                      or merger (if other than a Senior Note Guarantor or the
                      Company) unconditionally assumes all the obligations of
                      such Senior Note Guarantor, pursuant to a supplemental
                      Senior Note Indenture in form and substance reasonably
                      satisfactory to the Senior Note Trustee, under the Senior
                      Notes, the Senior Note Indenture and the Senior Subsidiary
                      Guarantee on the terms set forth herein or therein; and

                      (ii) immediately after giving effect to such transaction,
                      no Default or Event of Default exists.

                  (b) In case of any such consolidation, merger, sale or
         conveyance and upon the assumption by the successor corporation, by
         supplemental Senior Note Indenture, executed and delivered to the
         Senior Note Trustee and satisfactory in form to the Senior Note
         Trustee, of the Senior Subsidiary Guarantee endorsed upon the Senior
         Notes and the due and punctual performance of all of the covenants and
         conditions of the Senior Note Indenture to be performed by the Senior
         Note Guarantor, such successor corporation shall succeed to and be
         substituted for the Senior Note Guarantor with the same effect as if it
         had been named herein as a Senior Note Guarantor. Such successor
         corporation thereupon may cause to be signed any or all of the Senior
         Subsidiary Guarantees to be endorsed upon all of the Senior Notes
         issuable hereunder which theretofore shall not have been signed by the
         Company and


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         delivered to the Senior Note Trustee. All the Senior Subsidiary
         Guarantees so issued shall in all respects have the same legal rank and
         benefit under the Senior Note Indenture as the Senior Subsidiary
         Guarantees theretofore and thereafter issued in accordance with the
         terms of the Senior Note Indenture as though all of such Senior
         Subsidiary Guarantees had been issued at the date of the execution
         hereof,

                  (c) Except as set forth in Articles 4 and 5 of the Senior Note
         Indenture, and notwithstanding clauses (a) and (b) above, nothing
         contained in the Senior Note Indenture or in any of the Senior Notes
         shall prevent any consolidation or merger of a Senior Note Guarantor
         with or into the Company or another Senior Note Guarantor, or shall
         prevent any sale or conveyance of the property of a Senior Note
         Guarantor as an entirety or substantially as an entirety to the Company
         or another Senior Note Guarantor.

         5. RELEASES.

                  (a) In the event of a sale or other disposition of all of the
         assets of any Senior Note Guarantor, by way of merger, consolidation or
         otherwise, or a sale or other disposition of all to the capital stock
         of any Senior Note Guarantor, then such Senior Note Guarantor (in the
         event of a sale or other disposition, by way of merger, consolidation
         or otherwise, of all of the capital stock of such Senior Note
         Guarantor) or the corporation acquiring the property (in the event of a
         sale or other disposition of all or substantially all of the assets of
         such Senior Note Guarantor) will be released and relieved of any
         obligations under its Senior Subsidiary Guarantee; provided that the
         Net Proceeds of such sale or other disposition are applied in
         accordance with the applicable provisions of the Senior Note Indenture,
         including without limitation Section 4.10 of the Senior Note Indenture.
         Upon delivery by the Company to the Senior Note Trustee of an Officers'
         Certificate and an Opinion of Counsel to the effect that such sale or
         other disposition was made by the Company in accordance with the
         provisions of the Senior Note Indenture, including without limitation
         Section 4.10 of the Senior Note Indenture, the Senior Note Trustee
         shall execute any documents reasonably required in order to evidence
         the release of any Senior Note Guarantor from its obligations under its
         Senior Subsidiary Guarantee.

                  (b) Any Senior Note Guarantor not released from its
         obligations under its Senior Subsidiary Guarantee shall remain liable
         for the full amount of principal of and interest on the Senior Notes
         and for the other obligations of any Senior Note Guarantor under the
         Senior Note Indenture as provided in Article 10 of the Senior Note
         Indenture.

         6. NO RECOURSE AGAINST OTHERS. No past, present or future director,
officer, employee, incorporator, stockholder or agent of the Guaranteeing
Subsidiary, as such, shall have any liability for any obligations of the Company
or any Guaranteeing Subsidiary under the Senior Notes, any Senior Subsidiary
Guarantees, the Senior Note Indenture or this Supplemental Senior Note Indenture
or for any claim based on, in respect of, or by reason of, such obligations or
their creation Each Holder of the Senior Notes by accepting a Senior Note waives
and releases all such liability. The waiver and release are part of the
consideration for issuance of the Senior Notes. Such waiver may not be effective
to waive liabilities under the federal securities laws and it is the view of the
Commission that such a waiver is against public policy.



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         7. NEW YORK LAW TO GOVERN. THE INTERNAL LAW OF THE STATE OF NEW YORK
SHALL GOVERN AND BE USED TO CONSTRUE THIS SUPPLEMENTAL SENIOR NOTE INDENTURE BUT
WITHOUT GIVING EFFECT TO APPLICABLE PRINCIPLES OF CONFLICTS OF LAW TO THE EXTENT
THAT THE APPLICATION OF THE LAWS OF ANOTHER JURISDICTION WOULD BE REQUIRED
THEREBY.

         8. COUNTERPARTS. The parties may sign any number of copies of this
Supplemental Senior Note Indenture. Each signed copy shall be an original, but
all of them together represent the same agreement.

         9. EFFECT OF HEADINGS. The Section headings herein are for convenience
only and shall not affect the construction hereof.

         10. THE SENIOR NOTE TRUSTEE. The Senior Note Trustee shall not be
responsible in any manner whatsoever for or in respect of the validity or
sufficiency of this Supplemental Senior Note Indenture or for or in respect of
the recitals contained herein, all of which recitals are made solely by the
Guaranteeing Subsidiary and the Company.

         IN WITNESS WHEREOF, the parties hereto have caused this Supplemental
Senior Note Indenture to be duly executed and attested, all as of the date first
above written

                                        PEABODY NATURAL GAS, LLC

Dated: February 16, 2000
                                          By:  /S/ S. F. Schaab
                                               ---------------------------------
                                          Name:  S. F. Schaab
                                          Title: Vice President & Treasurer









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