Registration No. 333-30567

                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                   Form S-8-A

                           POST-EFFECTIVE AMENDMENT TO
                          REGISTRATION STATEMENT UNDER
                       THE SECURITIES EXCHANGE ACT OF 1933

                                 ARCH COAL, INC.
             (Exact name of registrant as specified in its charter)

                               Delaware 43-0921172
                (State or other jurisdiction of (I.R.S. Employer
               incorporation or organization) Identification No.)

               CityPlace One, Suite 300, St. Louis, Missouri 63141
               (Address of principal executive offices) (Zip Code)

                   COAL-MAC, INC. SAVINGS AND RETIREMENT PLAN
                            (Full title of the plan)

                                 JEFFRY N. QUINN
                                 ARCH COAL, INC.
                            SUITE 300, CITYPLACE ONE
                               ST. LOUIS, MO 63141
                                 (314) 994-2720
      (Name, address and telephone number of agent for service of process)






On July 1, 1997,  50,000 shares of Arch Coal, Inc.'s (the  "Registrant")  common
stock,  par value $0.01 per share (the "Common  Stock") were registered with the
Securities  and  Exchange  Commission  ("SEC")  ("the  Coal-Mac,  Inc.  CMI Plan
Registration  Statement")  for issuance in  connection  with and pursuant to the
terms of the  Coal-Mac,  Inc.  Savings and  Retirement  Plan (the  "Plan").  The
contents of the CMI Plan Registration  Statement are hereby  incorporated herein
by reference to the extent not replaced hereby.

On January 1, 1998, the Plan was merged into the Arch Coal, Inc. Employee Thrift
Plan (No. 333- 32777).  Seven Thousand Three Hundred  Seventy Two (7,372) shares
of registered Common Stock remained unissued at the time the Plan was merged.

Pursuant  to an  undertaking  in  Item  9(a)(3)  of the  CMI  Plan  Registration
Statement,   7,372  shares  of  the   Registrant's   Common  Stock,  are  hereby
deregistered,  as well as any corresponding  interests that have not been issued
under the Plan.






SIGNATURES
The Registrant

Pursuant to the  requirements  of the  Securities  Act of 1933,  the  registrant
certifies  that it has  reasonable  grounds to believe  that it meets all of the
requirements  for  filing on Form S-8 and has duly  caused  this  Post-Effective
Amendment  to the  Registration  Statement  to be  signed  on its  behalf by the
undersigned,  thereunto duly  authorized,  in the County of St. Louis,  State of
Missouri, as of March 16, 1998.

ARCH COAL, INC.

By: /s/ Jeffry N. Quinn
Jeffry N. Quinn
Senior Vice President - Law
and Human Resources, General
Counsel and Secretary

Pursuant to the requirements of the Securities Act of 1933, this  Post-Effective
Amendment  to the  Registration  Statement  has been  signed by the  undersigned
persons in the capacities  stated as of the 16th day of March,  1998.  SIGNATURE
CAPACITY

/s/ Steven F. Leer                       President, Chief Executive
Steven F. Leer                           Officer and Director
                                         (Principal Executive Officer)

/s/ Patrick A. Kriegshauser              Senior Vice President,
Patrick A. Kriegshauser                  Treasurer and Chief Financial Officer
                                         (Principal Financial Officer)

/s/ James P. Pye                         Controller
James P. Pye                             (Principal Accounting Officer)

James R. Boyd                            Director
Robert A. Charpie                        Director
Paul W. Chellgren                        Director
Thomas L. Feazell                        Director      By: /s/ Jeffry N. Quinn
Juan Antonio Ferrando                    Director
John R. Hall                             Director              Jeffry N. Quinn
Robert L. Hintz                          Director            As Attorney-in-Fact
Douglas H. Hunt                          Director
Steven F. Leer                           Director
Thomas Marshall                          Director
James L. Parker                          Director
J. Marvin Quin                           Director
Ronald Eugene Samples                    Director





THE PLAN.  Pursuant to the  requirements  of the  Securities  Act of 1933,  this
Post-Effective  Amendment to the  Registration  Statement has been signed by the
undersigned  Plan  Administrator  in the  City  of  Huntington,  State  of  West
Virginia, as of the 16th day of March, 1998.

COAL-MAC, INC.
SAVINGS AND RETIRMENT PLAN

By: /s/ Richard Phillips
       Richard Phillips
       Plan Administrator