Patterns of dispersal of distinctive Proterozoic and Paleozoic erratics across terrain formed on Archean and Aphebian crystalline rocks indicate that (1) ice never flowed from Hudson Bay into Keewatin in the region from the Manitoba border (lat 60°N) northward at least to lat 65°N; (2) westward-southwestward flow out of the bay, probably from a Labradorean dispersal center, interfaced with southward- and southeastward-flowing ice from the Keewatin dispersal center somewhere between Nelson River and Churchill; and (3) at least 300 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 3,000 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.

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