Index: trunk/LMDZ.MARS/libf/phymars/physiq_mod.F
===================================================================
--- trunk/LMDZ.MARS/libf/phymars/physiq_mod.F	(revision 2284)
+++ trunk/LMDZ.MARS/libf/phymars/physiq_mod.F	(revision 2285)
@@ -36,5 +36,6 @@
      &                      igcm_topdust_number
       use comsoil_h, only: inertiedat, ! soil thermal inertia
-     &                     tsoil, nsoilmx ! number of subsurface layers
+     &                     tsoil, nsoilmx,!number of subsurface layers
+     &                     mlayer,layer ! soil mid layer depths
       use geometry_mod, only: longitude, latitude, cell_area,
      &                        longitude_deg 
@@ -479,4 +480,8 @@
       REAL hsummit(ngrid)
 
+c when no startfi file is asked for init
+      real alpha,lay1 ! coefficients for building layers
+      integer iloop
+
 !      LOGICAL startphy_file
 
@@ -517,4 +522,5 @@
      &         mem_Mccn_co2,mem_Nccn_co2,
      &         mem_Mh2o_co2,watercap)
+
 
 #else
@@ -541,7 +547,17 @@
            ! starting without startfi.nc and with callsoil
            ! is not yet possible as soildepth default is not defined
-           if (callsoil) then
-              call abort_physic("physiq","callsoil option is not", 
-     &                     "yet available without startfi",1)
+           if (callsoil) then                     
+              ! default mlayer distribution, following a power law:
+              !  mlayer(k)=lay1*alpha**(k-1/2)
+              lay1=2.e-4
+	      alpha=2
+              do iloop=0,nsoilmx-1
+	         mlayer(iloop)=lay1*(alpha**(iloop-0.5))
+	      enddo
+              lay1=sqrt(mlayer(0)*mlayer(1))
+              alpha=mlayer(1)/mlayer(0)
+              do iloop=1,nsoilmx
+                 layer(iloop)=lay1*(alpha**(iloop-1))
+              enddo
            endif
            ! additionnal "academic" initialization of physics
@@ -558,5 +574,4 @@
         endif
 #endif
-
          if (pday.ne.day_ini) then
            write(*,*) "PHYSIQ: ERROR: bad synchronization between ",