Sublimation of ice through sediment in Beacon Valley, Antarctica

The time-dependent physics of ice sublimation through thin layers of till i s considered, to determine whether sublimation could be sufficiently slow t o permit the preservation of ice for 8 Ma in the Dry Valleys, Antarctica. T his could only happen if the ice had been very thick, bur other evidence (c rystal size, dating of other ice-cored moraines) is not consistent with thi s possibility. Steady-state models suggest that sublimation is rare-control led by vapor transport. A rime-dependent model coupling vapor concentration ,air pressure, temperature and ice concentration is formulated, and the res ulting equations solved non-linearly. No transient coupling between vapor c oncentration, air temperature and pressure that substantially slows down su blimation was found in the numerical experiments. This means either that va por transport is being slowed down by some unconsidered physical process or that the ice is much younger than 8 Ma.