Sediment, glaciohydraulic supercooling, and fast glacier flow

Glaciers often advance over proglacial sediments, which then may enhance basal motion. For glaciers with abundant meltwater, thermodynamic considerations indicate that the sediment-ice contact in the direction of ice flow tends toward an angle opposed to and somewhat steeper than the surface slope (by slightly more than 50%). A simple model based on this hypothesis yields the extent of over-ridden sediments as a function of sediment thickness and strength, a result that may be useful in guiding additional fieldwork for hypothesis testing. Sediment-floored as well as rock-floored over-deepenings are common features along glacier flow paths and are expected based on theories of glacier erosion, entrainment, transport and deposition.