CLAST COLLISION FREQUENCY AS AN INDICATOR OF GLACIER SLIDING RATE

The mechanical interaction between a lacier and subglacial sediment ca n be observed using an instrumented rod that we refer to as the UBC pl oughmeter. For clast-rich sediments, the rate of collision between cla sts and a rod dragged through these sediments should be related to the glacier sliding rate. By assuming that proglacial measurements of sed iment granulometry represent the subglacial granulometry of Trapridge Glacier, Yukon Territory. Canada, we have used ploughmeter results to obtain an estimated sliding. rate of similar to 45 mm d(-1), in good a greement with known rates. In addition, for a subglacial material trea ted as a solid-liquid dispersion having a linear viscous rheology, the force of collision experienced by the rod should be be proportional t o the effective sediment viscosity. Our estimate of similar to 2.0 x 1 0(10) Pa s agrees well with previously derived values.