Valleys Wallpaper, #11430

The terms U-shaped and V-shaped are descriptive terms of geography to characterize the form of Valleys. Most Valleys belong to one of these two main types or a mixture of them, at least with respect of the cross section of the slopes or hillsides.In geology, a valley (also called a vale, dale, glen or strath and near or in Appalachia, a draw) is a depression with predominant extent in one direction. A very deep river valley may be called a canyon or gorge.Examples of U-shaped Valleys are found in every mountainous region that has experienced glaciation, usually during the Pleistocene ice ages. Most present U-shaped Valleys started as V-shaped before glaciation. The glaciers carved it out wider and deeper, simultaneously changing the shape. This proceeds through the glacial erosion processes of glaciation and abrasion, which results in large rocky material (glacial till) being carried in the glacier. A material called boulder clay is deposited on the floor of the valley. As the ice melts and retreats, the valley is left with very steep sides and a wide, flat floor. A river or stream may remain in the valley. This replaces the original stream or river and is known as a misfit stream because it is smaller than one would expect given the size of its valley.