For a comprehensive list of world wide river valleys see: River valleys (category)
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, 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.
Some broad V examples are:
- North America: Black Canyon of the Gunnison National Park, and others in Grand Canyon NP
- Europe:
- Austria: narrow passages of upper Inn valley (Inntal), affluents of Enns a.s.o
- Switzerland: Napf region, Zurich Oberland, Engadin
- Germany: affluents to the middle reaches of Rhine and Mosel
Some of the first human complex societies originated in river valleys, such as that of the Nile, Tigris-Euphrates, Indus, Ganges, Yangtze, Huang He, Mississippi, and arguably Amazon. Inprehistory, the rivers were used as a source of freshwater and food (fish and game), as well as a place to wash and a sewer. The proximity of water moderated temperature extremes and provided a source for irrigation, stimulating the development of agriculture. Most of the first civilizations developed from these river valley communities.
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