WHAT ARE THE DOMINANT THERMOMECHANICAL PROCESSES IN THE BASAL SEDIMENT LAYER OF LARGE ICE SHEETS

The till-layer below the temperate base of all ice sheet is modelled a s a saturated viscous solid-fluid mixture. Its solid mass grows by abr ading material from the underlying rock-bed, and the water balance is affected by the draining of water into the rock-bed and melting of ice at the interface of the overlying ice sheet. This latter process is i nfluenced by the dissipation due to the power expended by: (i) the str esses; and (ii) Darcy-type interaction forces; as well as (iii) the sl iding of the ice: over the till-layer and of the latter over the rock- bed. All these mechanisms are likely to influence the thermodynamics o f the layer, a fact which is corroborated by a scaling analysis.