Fig. 21-H. Diagram showing ice advancing over the Turtle Mountain escarpment. When the Late Wisconsinan glacier (as well as earlier glaciers) advanced southward over Turtle Mountain in Manitoba, and eastward (at the west end of Turtle Mountain) in North Dakota, the compression caused it to shear large amounts of sediment into the ice. This part of the glacier became detached from the main part and stopped advancing. As it melted, the debris it contained became concentrated on the surface of the ice, slowing the melting process (see essay on dead-ice moraine). When all of the dead glacial ice melted, the result was the current land surface..
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