Low Profile of The Northwest Laurentide Ice Sheet

Abstract

The northwesternmost lobe of the Laurentide ice sheet flowed parallel to the Richardson and British mountains in the Northwest Territories, Canada. Reconstructed ice profiles from drift limits indicate that the early Wisconsin (?) and late Wisconsin Laurentide ice sheets in this area were thin and characterized by exceptionally low basal shear stresses of 1–30 kPa (0.01–0.3 bars). The low glacier profiles probably reflect subglacial sediment deformation at low basal shear stress and significant subglacial pore pressures. The Laurentide ice sheet was apparently not frozen to its base along its northwest margin at 69°N latitude. Rapid retreat rates of the northwest Laurentide ice sheet are probably due in part to its low initial profile. Solar energy would have been sufficient to melt the stagnant low profile ice sheet. The Laurentide ice sheet was asymmetric in the late Wisconsin, thicker in the east than in the west.