subroutine updlay(
     *  szlyd, bhrwc0, bhrwc,
     *  seagmx, seagmn, bseags,
     *  bhrwca, bhrwcw,
     *  bhtsmn, bhtmx0, bhtsmx,
     *  bsecr,
     *  k4d,
     *  slmin,slmax,
     *  bslagm,
     *  bs0ags, bslagx, bsdblk,
     *  dcump, 
     *  bszlyt, bsdagd, bslay, bsdcr,
     *  bsdsbk,
     *  bhzwid)

c     + + + GLOBAL COMMON BLOCKS + + +
*$noereference
      include 'p1werm.inc'
*$reference

c     + + + ARGUMENT DECLARATIONS + + +

      real szlyd(0:mnsz),
     *  bhrwc0(mnsz), bhrwc(mnsz),
     *  seagmx(mnsz), seagmn(mnsz), bseags(0:mnsz),
     *  bhrwca(mnsz), bhrwcw(mnsz),
     *  bhtsmn(mnsz), bhtmx0(mnsz), bhtsmx(mnsz),
     *  bsecr
      real k4d(mnsz)
      real slmin(mnsz),slmax(mnsz),
     * bslagm(0:mnsz),
     * bs0ags(0:mnsz), bslagx(0:mnsz), 
     * bsdblk(0:mnsz), dcump, 
     * bszlyt(mnsz), bsdagd(0:mnsz),
     * bsdcr, bsdsbk(mnsz),
     * bhzwid

      integer bslay

c     + + + LOCAL VARIABLES + + + 

      real hrwc0(mnsz), hrwc1(mnsz)
      real c4p
      real k4f, k4w, c4m
      parameter (k4f = 1.4, k4w = 0.36)
      real se0, se, se1
      integer ldx
      real chzwid

c     + + + LOCAL DEFINITIONS + + +
c
c   hrwc0     - relative water content on prior day of each layer
c   hrwc1     - relative water content on current day of each layer
c   k4f       - freezing process coef. to calc. aggregate stability
c   k4w       - wetting process coef. to calc. aggregate stability
c   se        - relative aggregate stability with partial update
c   se0       - relative aggregate stability prior to SOIL update
c   se1       - relative aggregate stability after SOIL update

c  + + +  UPDATE LAYERS: + + +

      chzwid = bhzwid

C ***      do while ((szlyd(ldx) .le. 300.) .or. (ldx .eq. 1))
      do ldx = 1, bslay

c        check for dry soil - then no changes
         if ((bhrwc(ldx) .le. bhrwcw(ldx)) .and.
     &      (bhrwc0(ldx) .le. bhrwcw(ldx))) go to 90

        call aggsta(bseags(ldx), seagmn(ldx), seagmx(ldx),
     *    bhrwc0(ldx), bhrwc0(ldx), bhrwcw(ldx), 
     *    bhrwca(ldx),
     *    hrwc1(ldx), bhrwc(ldx),
     *    bhtmx0(ldx), bhtsmn(ldx), bhtsmx(ldx), k4d(ldx),
     *    se0, k4f, se1, k4w, se)

        call asd(bslagm(ldx), slmin(ldx),
     *    slmax(ldx), bhtsmx(ldx), bs0ags(ldx),
     *    bslagx(ldx), c4p, se0, c4m, se1)

        call den(bsdblk(ldx), bsdsbk(ldx),
     *    bszlyt(ldx), bsdagd(ldx), dcump, chzwid)

   90    continue
C ***      if (szlyd(ldx) .gt. 300.) exit
      end do

c     calc. new crust stability
      bsecr = bseags(1)

c     update crust density                                         (S-58)
      bsdcr = 0.576 + 0.603 * bsdsbk(1)
      end