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                              FIRST AMENDMENT TO
                      THE AMENDED AND RESTATED CALMAT CO.
                    SUPPLEMENTAL EXECUTIVE RETIREMENT PLAN

          The AMENDED AND RESTATED CALMAT CO. SUPPLEMENTAL EXECUTIVE RETIREMENT
PLAN is amended, effective September 23, 1997, as follows:

          Section 1.1. of the AMENDED AND RESTATED CALMAT CO. SUPPLEMENTAL
EXECUTIVE RETIREMENT PLAN shall be amended in its entirety to read as follows:

"1.1  "Actuarial Equivalent" shall mean an actuarial equivalent value of an
      amount payable in a different form and/or at a different date computed in
      accordance with actuarial principles, and based on the following actuarial
      assumptions:

          Mortality:                         85% of the 1983 GAM Mortality Table

          Initial Maximum Interest Rate:     Four and One-Half Percent (4.5%)

      Notwithstanding the previous sentence, if the interest rate equal to 200
      basis points below the 30-year U.S. Treasury Bond yield as of any date
      subsequent to September 23, 1997 is less than the maximum interest rate in
      effect on such date, the maximum interest rate shall be adjusted downward
      to an interest rate equal to 200 basis points below the 30-year U.S.
      Treasury Bond yield on such date. Once the maximum interest rate has been
      adjusted downward, it shall not be thereafter adjusted upward, except as
      provided in Section 5.1. Moreover, the interest rate used by the Pension
      Benefit Guaranty Corporation to value immediate and deferred annuities
      shall be used at the time of a calculation under this Plan if its use will
      generate a greater benefit for or payment to a Participant, or create a
      greater contribution obligation to the Trust, than the maximum interest
      rate as set forth herein and in effect at such time.

      As the Committee deems necessary, in its sole discretion, the above
      actuarial assumptions may be adjusted from time to time, and no
      Participant shall be deemed to have any right, vested or nonvested,
      regarding the continued use of any previously adopted actuarial
      assumption; provided however that the mortality table shall assume no
      shorter life expectancies than the one provided above and provided further
      that the interest rate assumption shall in no event exceed the maximum
      interest rate in effect at the time of the adjustment by the Committee."

          IN WITNESS WHEREOF, CALMAT CO. has caused this First Amendment to the
AMENDED AND RESTATED CALMAT CO. SUPPLEMENTAL EXECUTIVE RETIREMENT PLAN to be
executed by its duly authorized officer this 25th day of November, 1997.
                                             --

                                         CALMAT CO.


                                         BY: /s/ Paul Stanford
                                             ----------------------------------
                                         ITS: Executive Vice President, General
                                              ---------------------------------
                                                  Counsel and Secretary