In geology, a valley (also called a vale or dale) is a depression with predominant extent in one direction. A very deep river valley may be called a canyon or gorge.

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.

A valley formed by flowing water, or river valley, is usually V-shaped. The exact shape will depend on the characteristics of the stream flowing through it. Rivers with steep gradients, as in mountain ranges, produce steep walls and a narrow bottom. Shallower slopes may produce broader and gentler valleys, but in the lowest stretch of a river, where it approaches its base level, it begins to deposit sediment and the valley bottom becomes a floodplain.