- This article is about the physical-geographic term. For places named "Valley" see Valley (disambiguation).
A valley is a landform, which can range from a few square miles (square
kilometers) to hundreds or even thousands of square miles (square kilometers) in area. It is typically a low-lying area of
land, surrounded by higher areas such as mountains or hills.
Valleys are formed by numerous geographical processes. Glacial
valleys, which are usually U- rather than V-shaped, were formed tens of thousands of years ago (most likely during the last
Ice Age) by the massive erosive power of glaciers. Several glacial valleys can be found in the English Lake District. Rift valleys, such as the Great Rift Valley, are formed by the expansion of the Earth's crust due to tectonic
activity beneath the Earth's surface. Valleys are, however, most commonly formed by fluvial activity (the action of running water, such as rivers), which
erodes the landscape.
Famous valleys
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