{This article is about the physical-geographic term. For places named "Valley" see Valley (disambiguation).)
A Valley is a landform, typically at least a few square miles (kilometers) but often hundreds or even thousands of square miles (kilometers), surrounded by higher areas, mountains, or hills.
Valleys are formed by numerous geographical processes, and can result in 'Glacial Valleys' formed millions of years ago by Glaciers, or Rift Valleys, formed by the expansion of the Earths crust due to activitiy beneath the Earths surface. Valleys are most commonly formed by fluvial activity (the action of running water), which erodes the landscape.
Famous valleys include: