- Plain
s.
Plains occur as
lowland s and at the bottoms ofvalley s but also onplateau s at highelevation s. They may have been formed from flowinglava , deposited by water, ice or wind, or formed byerosion by these agents from hills and mountains.Plains in many areas are important for
agriculture , because where the soils were deposited assediment s they may be deep andfertile , and the flatness facilitates mechanisation of crop production; or because they support grasslands which provide good grazing forlivestock .Types of terrestrial plains
*
Coastal plain , an area of low-lying land adjacent to a sea coast; the term is used especially where they contrast with hills, mountains or plateaux further inland.
*Fluvial plains are formed by rivers and streams, and may be one of these overlapping types:
**Flood plain , adjacent to a stream, river, lake or wetland that experiences occasional or periodicflooding .
**Alluvial plain , formed over a long period of time by ariver depositing sediment on its floodplain or bed which becomesalluvial soil. The difference between a floodplain and an alluvial plain is that the floodplain represents the area experiencing flooding fairly regularly in the present or recently, whereas an alluvial plain includes areas where the floodplain is now and used to be, or areas which only experience flooding a few times a century.
**Scroll plain , a plain through which a rivermeander s with a very low gradient.
*Lacustrine plain , a plain that originally formed in alacustrine environment, that is, as the bed of alake .
*Lava plain , formed by sheets of flowinglava .
*Till plain , a plain ofglacial till that forms when a sheet ofice becomes detached from the main body of aglacier and melts in place depositing thesediment s it carried.Other types of plain
The term may also be used for flat areas of the
ocean floor or for flat areas on moons and planets.
*Abyssal plain , a flat or very gently sloping area of the deep ocean basin floor.Notes and references
ee also
*Field
*Flooded grasslands and savannas
*Flood-meadow
*Grassland
*Liverpool Plains
*Machair
*Meadow
*Pasture
*Plateau
*Prairie
*Rangeland
*Savanna
*Steppe
*Water-meadow
*Wet meadow
*Veld
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