Valley

This article is about the physical-geographic term. For places named "Valley", see Valley (disambiguation).
"River valley" redirects here. For other uses, see River Valley.
Calchaquí Valley in Argentina
U-shaped valley in Glacier National Park, Montana, United States
Romsdalen in Western Norway has almost vertical walls.
Fljótsdalur in East Iceland, a rather flat valley
The Frades Valley in the mountainous region of Rio de Janeiro state, Brazil
Baemsagol valley of Jirisan, Korea

A valley is an elongated low area often running between hills or mountains and typically containing a river or stream running from one end to the other. Most valleys are formed by erosion of the land surface by rivers or streams over a very long period. Some valleys are formed through erosion by glacial ice. These glaciers may remain present in valleys in high mountains or polar areas.

At lower latitudes and altitudes, these glacially formed valleys may have been created or enlarged during ice ages but now are ice-free and occupied by streams or rivers. In desert areas, valleys may be entirely dry or carry a watercourse only rarely. In areas of limestone bedrock, dry valleys may also result from drainage now taking place underground rather than at the surface. Rift valleys arise principally from earth movements, rather than erosion. Many different types of valleys are described by geographers, using terms that may be global in use or else applied only locally.