Moraine

From Ohio History Central

Moraines are formed at the snout of a glacier when its forward advance equals its rate of retreat, thus causing the snout to remain in one position for a period of time, perhaps hundreds of years. Clay, sand, gravel, and boulders frozen in the ice are disgorged at the glacier snout, forming a hummocky ridge of till that outlines the margin of the glacier. As the Wisconsinan glacier made its final retreat from Ohio, it paused periodically and formed a series of recessional moraines.

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