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Glacial landforms
From Wikipedia, the free encyclopedia
Many now-familiar glacial landforms were created by the movement of huge sheets of ice called continental glaciers during the Pleistocene Epoch (more commonly called the Ice Age.)
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As the glaciers expanded, due to their accumulating weight of snow and ice , they crushed and scoured surface rocks and bedrock. The resulting erosional landforms include striations, cirques, glacial horns, arêtes, U-shaped valleys, roches moutonnées, and hanging valleys.
Later, when the glaciers retreated leaving behind their freight of crushed rock and sand (glacial drift), they created characteristic depositional landforms. Examples include glacial moraines, eskers, and kames. Drumlins are also landforms left behind by retreating glaciers. The stone walls of New England contain many glacial erratics, rocks that were dragged by a glacier many miles from their bedrock origin.
Lakes and ponds can also be caused by glacial movement. Kettle lakes form when a retreating glacier leaves behind an underground or surface chunk of ice that later melts to form a depression containing water. Moraine-dammed lakes occur when a stream (or snow runoff) is dammed by glacial debris. Jackson Lake and Jenny Lake in Grand Teton National Park are examples of moraine-dammed lakes, although Jackson Lake is also enhanced by a man-made dam.