Basal-flow conditions at the northeastern margin of the Laurentide Ice Sheet, Lancaster Sound
A major moraine system developed by outlet glaciers of the Laurentide Ice Sheet on coastal mountains of Bylot Island provides a basis for reconstructing paleoglacier surfaces and estimating basal shear stresses within the ice. The system, named Eclipse moraine, lies between elevations of 100 and 500 m asl and can be traced almost continuously over distances of 50–70 km. Where the glaciers flowed inland within valleys, the outline of the moraine on valley walls is used to portray the profile of the glacier along the valley median. If ideal plastic flow is assumed, ice thicknesses and surface slopes derived from the reconstructed profiles indicate yield stresses of about 125 ± 46 kPa. Reconstructed profiles of the main outlet glaciers entering Baffin Bay from Lancaster Sound and Pond Inlet indicate lesser yield stresses of about 55–80 kPa, respectively, within the channels; estimates are 35–60 kPa if isostatic depression is assumed. Calculations indicate mat basal shear stresses in the channels were near th...