V-shaped valleys are caused by forces such as erosion and rivers. ... Erosion by rivers is a main valley-forming process; other processes, such as movement of the earth's crust and glaciers, also have an important part in some cases. The rate at which a river deepens its valley depends on several factors.
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. Shallower slopes may produce broader and gentler valleys.
U-shaped valleys, trough valleys or glacial troughs, are formed by the process of glaciation. They are characteristic of mountain glaciation in particular. ... Glaciated valleys are formed when a glacier travels across and down a slope, carving the valley by the action of scouring.
A valley is made deeper by a stream of water or a river as it flows from the high land to the lower land, and into a lake or sea. Some valleys are made by glaciers which are slow-moving rivers of ice. When water or ice make a valley deeper or wider, this is called erosion.
A rift valley is a linear-shaped lowland between several highlands or mountain ranges created by the action of a geologic rift or fault. A rift valley is formed on a divergent plate boundary, a crustal extension, a spreading apart of the surface, which is subsequently further deepened by the forces of erosion.