In geography, a plain, commonly known as flatland, is a flat expanse of land that generally does not change much in elevation, and is primarily treeless. Plains occur as along or at the base of , as , and as or Highland. Plains are one of the major on earth, being present on all continents and covering more than one-third of the world's land area. Plains in many areas are important for agriculture. There are various types of plains and on them. in Sri Lanka.]]
Description
A plain or flatland is a flat expanse of land with a layer of grass that generally does not change much in
elevation, and is primarily treeless. Plains occur as
along
or at the base of
, as
, and as
or
Highland.
Plains are one of the major
on earth, where they are present on all continents, and cover more than one-third of the world's land area.
In a valley, a plain is enclosed on two sides, but in other cases a plain may be delineated by a complete or partial ring of hills, by mountains, or by . Where a geological region contains more than one plain, they may be connected by a Mountain pass (sometimes termed a gap). Coastal plains mostly rise from sea level until they run into elevated features such as mountains or plateaus.
on plains include grassland (temperate or subtropical), steppe (semi-arid), savannah (tropical climate) or tundra (polar climate). In a few instances, and may also be considered plains.
Plains in many areas are important for agriculture because where the soils were deposited as they may be deep and fertile, and the flatness facilitates mechanization of crop production; or because they support grasslands which provide good grazing for livestock.[Powell, W. Gabe. 2009. Identifying Land Use/Land Cover (LULC) Using National Agriculture Imagery Program (NAIP) Data as a Hydrologic Model Input for Local Flood Plain Management. Applied Research Project, Texas State University.]
Types of plain
Depositional plains
The types of depositional plains include:
-
, flat or very gently sloping areas of the deep ocean basin.
-
Planitia , the Latin language word for plain, is used in the naming of plains on extraterrestrial objects (planets and moons), such as Hellas Planitia on Mars or Sedna Planitia on Venus.
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Alluvial plains, which are formed by rivers and which may be one of these overlapping types:
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, formed over a long period of time by a river depositing sediment on their flood plains or beds, which become alluvial soil. The difference between a flood plain and an alluvial plain is: a flood plain represents areas experiencing flooding fairly regularly in the present or recently, whereas an alluvial plain includes areas where a flood plain is now and used to be, or areas which only experience flooding a few times a century.
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Flood plain, adjacent to a lake, river, stream, or wetland that experiences occasional or periodic flooding.
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Scroll plain, a plain through which a river with a very low gradient.
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Glacial plains, formed by the movement of glaciers under the force of gravity:
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Outwash plain (also known as sandur; plural sandar), a glacial out-wash plain formed of sediments deposited by melt-water at the terminus of a glacier. Sandar consist mainly of stratified (layered and sorted) gravel and sand.
[Magilligan F.J., Gomez B., Mertes L.A.K., Smith, L.C. Smith N.D., Finnegan D., Garvin J.B., Geomorphic effectiveness, sandur development, and the pattern of landscape response during jökulhlaups: Skeiðarársandur, southeastern Iceland, Geomorphology 44 (2002) 95–113][Smith L.C., Sheng Y., Magilligan F.J., Smith N.D., Gomez B., Mertes L., Krabill W.B., Garven J.B., Geomorphic impact and rapid subsequent recovery from the 1996 Skeiðarársandur jökulhlaup, Iceland, measured with multi-year airborne lidar. Geomorphology vol. 75 Is. 1–2 (2006) 65–75]
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, plain of glacial till that form when a sheet of ice becomes detached from the main body of a glacier and melts in place depositing the it carries. Till plains are composed of unsorted material (till) of all sizes.
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, plains that originally formed in a lacustrine environment, that is, as the bed of a lake.
[United States. Department of Conservation. Division of Geology. Glacial Sluceways and Lacustrine Plains of Southern Indiana. By William D. Thornburry. Bloomington: n.p., 1950. Web. <>.]
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, formed by sheets of flowing lava.
Erosional plains
Erosional plains have been leveled by various agents of denudation such as running water, rivers, wind and glacier which wear out the rugged surface and smoothens them. Plain resulting from the action of these agents of denudation are called
(almost plain) while plains formed from wind action are called
.
Structural plains
Structural plains are relatively undisturbed horizontal surfaces of the Earth. They are structurally depressed areas of the world that make up some of the most extensive natural lowlands on the Earth's surface.
Notable examples
America
Caribbean and South America
North America
Asia
Eastern Asia
North Asia
South Asia
Western Asia
Europe
Central Europe
Eastern Europe
Northern Europe
Southern Europe
Oceania
Australia
New Zealand
See also
External links
