!--------1---------2---------3---------4---------5---------6---------7---------8
subroutine time_evolution 
!--------1---------2---------3---------4---------5---------6---------7---------8
  use global_constants, only : rkind, itmax, dt, time0, time, year &
    & , GO_NEXT, W_ALTERATION, temperature_melting_rock, D_REACTION, Myr, Rocky_Core, Ordinary_Chondrite
  use material_parameters, only : iw, ir, ii, mn, melt, material_check &
    & , ir_old, iw_old, ice_reach_rock &
    & , mass_ratio_rock, mass_ratio_anhydrous_rock, frez_start &
    & , mass_ratio_ice, mass_ratio_water, mass_ratio_hydrous_rock, radius_water
  use global_parameters, only :  irmax, temp, fw, temp_max
  use energy, only : energy_check, temp_old, lat_energy, set_energy
  use aqueous, only : aqueous_check, alteration_heat_bak, flux_alt
  use dehydration, only : dehydration_check, temperature_dehydration
  use heat_radiogenic, only : iAl, ftime
  use energy_dump, only : energy_w_dump, energy_r_dump
  use heat_parameters, only : latent_heat_vapor
  use diffusion, only : diffusion_check
  implicit none
  integer :: it, i, time_Myr
  time = time0
  temp_old(0:irmax) = temp(0:irmax)
  do it = 1, itmax/2
    temp_max(0:irmax) = max(temp_max(0:irmax),temp_old(0:irmax))
    time = time0 + dt*real(it) 
    call set_energy
    flux_alt = 0._rkind
    if(W_ALTERATION) call alteration_heat_bak(it)
    temp_old(0:irmax) = temp(0:irmax)
    time_Myr = (time/year+ftime(iAl))/Myr
if(Rocky_core) then
  if(.NOT.ice_reach_rock) then
    if(iw == 0) then
      call fdm_explicit_init
    elseif(iw /= 0 .AND. ii-iw >= 2) then
      call fdm_explicit_water
      if(ir > 0) call flux_check
      call pressure_check
    elseif(iw /= 0 .AND. ii-iw <= 1) then
      call fdm_explicit_water_ice
      call flux_check
      call pressure_check
    endif
    do i = 0, irmax
      if(mn(i)/=4.AND.mn(i)/=2.AND.mn(i)/=1) call material_check(i)
      if((mn(i) >= 7 .AND. mn(i)<= 9) .OR. mn(i) == 3 .OR. mn(i) == 11) ii = i
    enddo
    if(W_ALTERATION) then
      call aqueous_check
      if(D_REACTION) call dehydration_check
    elseif(.NOT.W_ALTERATION) then
      mass_ratio_anhydrous_rock(0:irmax) = mass_ratio_rock(0:irmax)
    endif
    call radius_check
  elseif(ice_reach_rock) then
    call fdm_explicit_init
    call pressure_check
    if(D_REACTION) call dehydration_check
    do i = 0, ir
      if(mn(i)/=4) call material_check(i)
    enddo
  endif
elseif(.NOT.Rocky_core) then
  call fdm_explicit_init
  call pressure_check_nocore
    do i = 0, irmax
      if(mn(i)/=4.AND.mn(i)/=2.AND.mn(i)/=1) call material_check(i)
      if((mn(i) >= 7 .AND. mn(i)<= 9) .OR. mn(i) == 3 .OR. mn(i) == 11) ii = i
    enddo
    if(W_ALTERATION) then
      call aqueous_check
      if(D_REACTION) call dehydration_check
    elseif(.NOT.W_ALTERATION) then
      mass_ratio_anhydrous_rock(0:irmax) = mass_ratio_rock(0:irmax)
    endif
endif
  if(temp(0)>=temperature_melting_rock) then
    GO_NEXT=.TRUE.
    call log_error(0,'temp0>temp_melt_rock')
  endif
  if(GO_NEXT) exit
    if(mod(it,itmax/10000)==0) then
      call graph
    endif
    ir_old = ir
    iw_old = iw
  enddo
  return
end subroutine time_evolution