Keewatin Ice Sheet—Re-evaluation of the traditional concept of the Laurentide Ice Sheet

Patterns of dispersal of distinctive Proterozoic and Paleozoic erratics across terrain formed on Archean and Aphebian crystalline rocks indicate that (1) ice never f lowed from Hudson Bay into Keewatin in the region from the Manitoba border (lat 6 0 ° N ) northward at least to lat 65°N; (2) westward-southwestward f low out of the bay, probably from a Labradorean dispersal center, interfaced with southwardand southeastwardflowing ice from the Keewatin dispersal center somewhere between Nelson River and Churchill; and (3) at least 3 0 0 km of dispersal of distinctive erratics observed from the vicinity of the last position of the Keewatin Ice Divide to the present coast of Hudson Bay required considerably more time than the 1,000 to 3 , 0 0 0 yr that the divide has traditionally been thought to have existed. In fact, the Keewatin Ice Divide and its precursors represent the centers of an independent, land-based ice sheet that probably existed throughout the period of Wisconsin Glaciation.