Is the Basal Ice of a Temperate Glacier at the Pressure Melting Point

摘要: Certain aspects of the flow glaciers suggest that molecular adhesion contributes to basal friction sliding at speeds below those surging glaciers. Laboratory experiments indicate this will only occur if some part ice-rock contact is “cold”, pressure melting point (p.m.p.), a few tenths degree being sufficient. Field evidence scanty, but suggests such cold patches may exist base temperate glacier. Discussion pressure-melting within ice mass, as distinct from processes contact, excess water formed in zones high-pressure up-stream obstacles. If squeezed out by pressure, we have simple heat pump tend cool ice. The warm again result thermal conduction and internal friction, before reaching p.m.p. it can produce "cold" roughly estimated be 0. 1 1.0 m extent. Another factor could cause intermittent interface arises changes pressures with time beneath major weight glacier supported thin film relatively low small proportion which are high, then over large area must balance however low-pressure rises, smaller areas stress concentration suffer proportionately greater decrease maintain total between weight, take place rapidly, matter hours, order metre or more across, freeze bed stresses relieved. This stick-slip motion Pressure-temperature effects help explain certain features glacial erosion, intense grinding on top surface roche moutonee plucking down-stream side.