A valley is a low area between hills or mountains often with a river running through it. In geology, a valley or dale is a depression that is longer than it is wide. Most valleys belong to one of two main types or a mixture of them, with respect to 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 bottom. However, 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. Aerial 4K UHD 3840×2160.