The lake level remained at 640' above sea level, but the ice margin was a third of the way north, opening a channel across Michigan, draining the Lake Saginaw and Lake Whittlesey proglacial lakes in the Lake Huron and Lake Erie basins.
The lake level remained at 640' above sea level, but the ice margin was a third of the way north, creating an opening across Michigan that drained the Lake Saginaw and Lake Whittlesey proglacial lakes in the Lake Huron and Lake Erie basins.