Exhibit 4.13


             FOURTH SUPPLEMENTAL SENIOR SUBORDINATED NOTE INDENTURE

     FOURTH SUPPLEMENTAL SENIOR SUBORDINATED NOTE INDENTURE (this "Supplemental
Senior Subordinated 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 Subordinated Note Guarantors (as defined in the Senior
Subordinated Note Indenture referred to herein) and State Street Bank and Trust
Company, as Senior Subordinated Note Trustee under the Senior Subordinated Note
Indenture referred to below (the "Senior Subordinated Note Trustee").

                                   WITNESSETH

     WHEREAS, the Company has heretofore executed and delivered to the Senior
Subordinated Note Trustee a Senior Subordinated Note Indenture (the "Senior
Subordinated Note Indenture"), dated as of May 18, 1998 providing for the
issuance of an aggregate principal amount of up to $650.0 million of 9-5/8%
Senior Subordinated Notes due 2008 (the "Senior Subordinated Notes");

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

     WHEREAS, pursuant to Section 9.01 of the Senior Subordinated Note
Indenture, the Senior Subordinated Note Trustee is authorized to execute and
deliver this Supplemental Senior Subordinated 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 Subordinated Note Trustee mutually
covenant and agree for the equal and ratable benefit of the Holders of the
Senior Subordinated Notes as follows:

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

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

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

               (i) the principal of and interest on the Senior Subordinated
          Notes will be promptly paid in full when due, whether at maturity, by
          acceleration, redemption or otherwise, and interest on the overdue
          principal of and interest on the Senior Subordinated Notes, if any, if
          lawful, and all other obligations of the Company to the Holders or the
          Senior Subordinated 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 Subordinated 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 Subordinated 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 Subordinated Notes
     or the Senior Subordinated Note Indenture, the absence of any action to
     enforce the same, any waiver or consent by any Holder of the Senior
     Subordinated 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 Subordinated 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 Subordinated Subsidiary Guarantee shall not be discharged
     except by complete performance of the obligations contained in the Senior
     Subordinated Notes and the Senior Subordinated Note Indenture.

          (e) If any Holder or the Senior Subordinated Note Trustee is required
     by any court or otherwise to return to the Company, the Senior Subordinated
     Note Guarantors, or any custodian, Senior Subordinated Note Trustee,
     liquidator or other similar official acting in relation to either the
     Company or the Senior Subordinated Note Guarantors, any amount paid by
     either to the Senior Subordinated Note Trustee or such Holder, this
     Subordinated 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 Subordinated Note Guarantors, on the one
     hand, and the Holders and the Senior Subordinated 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 Subordinated Note
     Indenture for the purposes of this Subordinated Subsidiary Guarantee,
     notwithstanding any stay, injunction or other prohibition preventing such
     acceleration in respect of the obligations guaranteed hereby, and (y) in
     the event of any declaration of acceleration of such obligations as
     provided in Article 6 of the Senior Subordinated Note Indenture, such
     obligations (whether or not due and payable) shall forthwith become due and
     payable by the Senior Subordinated Note Guarantors for the purpose of this
     Subordinated Subsidiary Guarantee.

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

          (i) Pursuant to Section 11.02 of the Senior Subordinated 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 Subordinated Note Guarantor in respect of
     the obligations of such other Senior Subordinated Note Guarantor under
     Article 11 of the Senior Subordinated Note Indenture shall result in the
     obligations of such Senior Subordinated Note Guarantor under its
     Subordinated Subsidiary Guarantee not constituting a fraudulent transfer or
     conveyance.

     3. EXECUTION AND DELIVERY. Each Guaranteeing Subsidiary agrees that the
Subordinated Subsidiary Guarantees shall remain in full force and effect
notwithstanding any failure to endorse on each Senior Subordinated Note a
notation of such Subordinated 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 Subordinated Note Guarantor is the
     surviving Person) another corporation, Person or entity whether or not
     affiliated with such Senior Subordinated Note Guarantor unless:

               (i) subject to Section 11.05 of the Senior Subordinated Note
          Indenture, the Person formed by or surviving any such consolidation or
          merger (if other than a Senior Subordinated Note Guarantor or the
          Company) unconditionally assumes all the obligations of such Senior
          Subordinated Note Guarantor, pursuant to a supplemental Senior
          Subordinated Note Indenture in form and substance reasonably
          satisfactory to the Senior Subordinated Note Trustee, under the Senior
          Subordinated Notes, the Senior Subordinated Note Indenture and the
          Subordinated 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
     Subordinated Note Indenture, executed and delivered to the Senior
     Subordinated Note Trustee and satisfactory in form to the Senior
     Subordinated Note Trustee, of the Subordinated Subsidiary Guarantee
     endorsed upon the Senior Subordinated Notes and the due and punctual
     performance of all of the covenants and conditions of the Senior
     Subordinated Note Indenture to be performed by the Senior Subordinated Note
     Guarantor, such successor corporation shall succeed to and be substituted
     for the Senior Subordinated Note Guarantor with the same effect as if it
     had been named herein as a Senior Subordinated Note Guarantor. Such
     successor corporation thereupon may cause to be signed any or all of the
     Subordinated Subsidiary Guarantees to be endorsed upon all of the Senior
     Subordinated Notes issuable hereunder which theretofore shall not have been
     signed by the Company and delivered to the Senior Subordinated Note
     Trustee. All the Subordinated Subsidiary Guarantees so issued shall in all
     respects have the same legal rank and benefit under the Senior Subordinated
     Note Indenture as the Subordinated Subsidiary Guarantees theretofore and
     thereafter issued in accordance with the terms of the Senior Subordinated
     Note Indenture as though all of, such Subordinated 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 Subordinated
     Note Indenture, and notwithstanding clauses (a) and (b) above, nothing
     contained in the Senior Subordinated Note Indenture or in any of the Senior
     Subordinated Notes shall prevent any consolidation or merger of a Senior






     Subordinated Note Guarantor with or into the Company or another Senior
     Subordinated Note Guarantor, or shall prevent any sale or conveyance of the
     property of a Senior Subordinated Note Guarantor as an entirety or
     substantially as an entirety to the Company or another Senior Subordinated
     Note Guarantor.

     5. RELEASES.

          (a) In the event of a sale or other disposition of all of the' assets
     of any Senior Subordinated Note Guarantor, by way of merger, consolidation
     or other-wise, or a sale or other disposition of all to the capital stock
     of any Senior Subordinated Note Guarantor, then such Senior Subordinated
     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 Subordinated 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 Subordinated Note Guarantor)
     will be released and relieved of any obligations under its Subordinated
     Subsidiary Guarantee; provided that the Net Proceeds of such sale or other
     disposition are applied in accordance with the applicable provisions of the
     Senior Subordinated Note Indenture, including without limitation Section
     4.10 of the Senior Subordinated Note Indenture. Upon delivery by the
     Company to the Senior Subordinated 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
     Subordinated Note Indenture, including without limitation Section 4. 10 of
     the Senior Subordinated Note Indenture, the Senior Subordinated Note
     Trustee shall execute any documents reasonably required in order to
     evidence the release of any Senior Subordinated Note Guarantor from its
     obligations under its Subordinated Subsidiary Guarantee.

          (b) Any Senior Subordinated Note Guarantor not released from its
     obligations under its Subordinated Subsidiary Guarantee shall remain liable
     for the full amount of principal of and interest on the Senior Subordinated
     Notes and for the other obligations of any Senior Subordinated Note
     Guarantor under the Senior Subordinated Note Indenture as provided in
     Article I of the Senior Subordinated 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 Subordinated Notes, any
Subordinated Subsidiary Guarantees, the Senior Subordinated Note Indenture or
this Supplemental Senior Subordinated 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 Subordinated Notes by accepting a Senior Subordinated Note waives
and releases all such liability. The waiver and release are part of the
consideration for issuance of the Senior Subordinated 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.

     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 SUBORDINATED 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  Subordinated 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 SUBORDINATED NOTE TRUSTEE. The Senior Subordinated Note
Trustee shall not be responsible in any manner whatsoever for or in respect of
the validity or sufficiency of this Supplemental Senior Subordinated 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
Subordinated Note Indenture to be duly executed and attested, all as of the date
first above written.

Dated: February 16, 2000

                                   PEABODY NATURAL GAS, LLC


                                   By: /s/ S. F. Schaab
                                      -----------------------------------------
                                   Name: S. F. Schaab
                                   Title: Vice President & Treasurer