Plain Explained
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 lowlands along valleys or at the base of mountains, as coastal plains, and as plateaus or uplands. Plains are one of the major landforms 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 biomes on them.
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 lowlands along valleys or at the base of mountains, as coastal plains, and as plateaus or uplands.[1] Plains are one of the major landforms on earth, where they are present on all continents, and cover more than one-third of the world's land area.[2]
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 cliffs. Where a geological region contains more than one plain, they may be connected by a pass (sometimes termed a gap). Coastal plains mostly rise from sea level until they run into elevated features such as mountains or plateaus.[3] Plains can be formed from flowing lava; from deposition of sediment by water, ice, or wind; or formed by erosion by the agents from hills or mountains.
Biomes on plains include grassland (temperate or subtropical), steppe (semi-arid), savannah (tropical) or tundra (polar). In a few instances, deserts and rainforests may also be considered plains.[4]
Plains in many areas are important for agriculture because where the soils were deposited as sediments 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.[5]
Types of plain
Depositional plains
The types of depositional plains include:
- Abyssal plains, flat or very gently sloping areas of the deep ocean basin.[6] [7]
- Planitia, the Latin 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.
- Alluvial plains, which are formed by rivers and which may be one of these overlapping types:
- Alluvial plains, 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.[8]
- Flood plain, adjacent to a lake, river, stream, or wetland that experiences occasional or periodic flooding.
- Scroll plain, a plain through which a river meanders with a very low gradient.
- Glacial plains, formed by the movement of glaciers under the force of gravity:
- 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.[9] [10]
- Till plains, 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 sediments it carries. Till plains are composed of unsorted material (till) of all sizes.
- Lacustrine plains, plains that originally formed in a lacustrine environment, that is, as the bed of a lake.[11]
- Lava plains, formed by sheets of flowing lava.[12]
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 peneplains (almost plain) while plains formed from wind action are called pediplains.[13]
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.[14]
Notable examples
thumb|View of the South Småland peneplain at Store Mosse National Park in Sweden.
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
Notes and References
- Rood. Stewart B.. Pan. Jason. Gill. Karen M.. Franks. Carmen G.. Samuelson. Glenda M.. Shepherd. Anita. 2008-02-01. Declining summer flows of Rocky Mountain rivers: Changing seasonal hydrology and probable impacts on floodplain forests. Journal of Hydrology. 349. 3–4. 397–410. 10.1016/j.jhydrol.2007.11.012. 2008JHyd..349..397R.
- Book: Geoff C. Brown . Understanding the Earth . C. J. Hawkesworth . R. C. L. Wilson . Cambridge University Press . 1992 . 978-0-521-42740-1 . 2nd . 93 . https://web.archive.org/web/20160603090000/https://books.google.com/books?id=Kgk4AAAAIAAJ&pg=PA93 . 2016-06-03 . live.
- Book: Whittow, John . 1984. Dictionary of Physical Geography. London. Penguin. 467. 978-0-14-051094-2.
- Book: Gornitz . Vivien . 2009 . Encyclopedia of Paleoclimatology And Ancient Environments . Springer . Dordrecht . 665 . 9781402045516.
- 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.
- Encyclopedia: Goudie. A. S. . Andrew Goudie (geographer) . Encyclopedia of Geomorphology . Denudation chronology . 2004 . 244–248.
- Book: Vinogradova, N.G. . The Biogeography of the Oceans . Zoogeography of the Abyssal and Hadal Zones . 32 . 325–387 . 1997 . 10.1016/S0065-2881(08)60019-X . Advances in Marine Biology . 9780120261321.
- Web site: Glossary of Landform and Geologic Terms . . National Soil Survey Handbook—Part 629 . April 2013 . PDF . 17 August 2016 . live . https://web.archive.org/web/20161022224040/http://www.nrcs.usda.gov/wps/PA_NRCSConsumption/download/?cid=nrcs142p2_053182&ext=pdf . 22 October 2016 .
- 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
- 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. Archived copy . 2015-12-16 . live . https://web.archive.org/web/20160303230354/https://scholarworks.iu.edu/dspace/bitstream/handle/2022/205/B04.pdf?sequence=1 . 2016-03-03 . >.
- Web site: Lava Plateaus. 2014-01-26. live. https://web.archive.org/web/20131114161356/http://vulcan.wr.usgs.gov/Glossary/LavaPlateaus/description_lava_plateaus.html. 2013-11-14.
- Encyclopedia: Migoń. Piotr. Piotr Migoń. Goudie. A.S.. Encyclopedia of Geomorphology. Planation surface. 2004. 788–792.
- Encyclopedia: Encyclopedia Britannica. Pediplain.
