{{short description|Expanse of land that is mostly flat and treeless}}{{other uses|Plain (disambiguation)|Plains (disambiguation)}}{{Cleanup|reason=consistency and clarity|date=April 2021|talksection=Cleanup_needed}}File:Maniototoevening.jpg|thumb|right|The Kakanui Range dominates the eastern horizon of the Maniototo Plain of New Zealand New ZealandIn 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.File:Horton Plains 2021.jpg|thumb|Montane plains as seen in Horton Plains in Sri Lanka 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 lowlands along valleys or at the base of mountains, as coastal plains, and as plateaus or uplands.JOURNAL, 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, 3â€“4, 397â€“410, 10.1016/j.jhydrol.2007.11.012, 2008JHyd..349..397R, 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.BOOK, Geoff C. Brown,books.google.com/books?id=Kgk4AAAAIAAJ&pg=PA93, Understanding the Earth, C. J. Hawkesworth, R. C. L. Wilson, Cambridge University Press, 1992, 978-0-521-42740-1, 2nd, 93,web.archive.org/web/20160603090000/https://books.google.com/books?id=Kgk4AAAAIAAJ&pg=PA93, 2016-06-03, live, 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.BOOK, Whittow, John, 1984, Dictionary of Physical Geography, London, Penguin, 467, 978-0-14-051094-2, 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.BOOK, Gornitz, Vivien, 2009, Encyclopedia of Paleoclimatology And Ancient Environments, Springer, Dordrecht, 665, 9781402045516, 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.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:

Abyssal plains, flat or very gently sloping areas of the deep ocean basin.ENCYCLOPEDIA, Goudie, A. S., Andrew Goudie (geographer), Encyclopedia of Geomorphology, Denudation chronology, 2004, 244â€“248, BOOK, N.G., Vinogradova, The Biogeography of the Oceans, Zoogeography of the Abyssal and Hadal Zones, 32, 325â€“387, 1997, 10.1016/S0065-2881(08)60019-X, Advances in Marine Biology, 9780120261321,
{{anchor|Planitia}}Planitia {{IPAc-en|p|l|É™|’|n|Éª|Êƒ|i|É™}}, 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.WEB,www.nrcs.usda.gov/wps/PA_NRCSConsumption/download?cid=nrcs142p2_053182&ext=pdf, Glossary of Landform and Geologic Terms, National Cooperative Soil Survey, National Soil Survey Handbookâ€”Part 629, April 2013, PDF, 17 August 2016, live,www.nrcs.usda.gov/wps/PA_NRCSConsumption/download/?cid=nrcs142p2_053182&ext=pdf," title="web.archive.org/web/20161022224040www.nrcs.usda.gov/wps/PA_NRCSConsumption/download/?cid=nrcs142p2_053182&ext=pdf,">web.archive.org/web/20161022224040www.nrcs.usda.gov/wps/PA_NRCSConsumption/download/?cid=nrcs142p2_053182&ext=pdf, 22 October 2016, File:é›ªå±±ä¸‹çš„æˆéƒ½å¸‚å¤©é™…çº¿ Chengdu skyline with snow capped mountains.jpg|thumb|Chengdu Plain, Sichuan Sichuan
- 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.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 jÃ¶kulhlaups: SkeiÃ°arÃ¡rsandur, southeastern Iceland, Geomorphology 44 (2002) 95â€“113Smith 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 SkeiÃ°arÃ¡rsandur jÃ¶kulhlaup, Iceland, measured with multi-year airborne lidar. Geomorphology vol. 75 Is. 1â€“2 (2006) 65â€“75
- 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.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. .
Lava plains, formed by sheets of flowing lava.WEB,vulcan.wr.usgs.gov/Glossary/LavaPlateaus/description_lava_plateaus.html, Lava Plateaus, 2014-01-26, live,vulcan.wr.usgs.gov/Glossary/LavaPlateaus/description_lava_plateaus.html," title="web.archive.org/web/20131114161356vulcan.wr.usgs.gov/Glossary/LavaPlateaus/description_lava_plateaus.html,">web.archive.org/web/20131114161356vulcan.wr.usgs.gov/Glossary/LavaPlateaus/description_lava_plateaus.html, 2013-11-14,

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.ENCYCLOPEDIA, MigoÅ„, Piotr, Piotr MigoÅ„, Goudie, A.S., Encyclopedia of Geomorphology, Planation surface, 2004, 788â€“792,

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.ENCYCLOPEDIA, Encyclopedia Britannica, Pediplain,global.britannica.com/science/pediplain, File:Curry County Eastern New Mexico 2010.jpg|thumb|Curry County, eastern New Mexico, on the North American Great Plains Great Plains

Notable examples

{{See also|Category: Plains by country}}File:Esta%C3%A7%C3%A3o_Ecol%C3%B3gica_do_Taim.jpg|thumb|The Pampas are a huge area of fertile grasslands grasslandsFile:Bozan_village.jpg|thumb|Nineveh Plains (Bozan, Iraq Bozan, IraqFile:Liminka field 20080726 01.jpg|thumb|A field plain in Liminka, Finland FinlandFile:View of Fields at Biccavolu.jpg|thumb|View of Fields at Biccavolu, Eastern coastal plains, Andhra Pradesh Andhra Pradesh(File:Yilan Plain 2011-05-11.jpg|thumb|Yilan Plain, Taiwan)file:Store Mosse Stora Gungflyet.jpg|thumb|View of the South SmÃ¥land peneplain at Store Mosse National Park Store Mosse National ParkFile:Nsomersetlevels.JPG|thumb|North Somerset Levels taken from Dolebury Warren Dolebury WarrenFile:Fulda countryside.jpg|thumb|Terrain near the central German town of Fulda FuldaFile:ArgeÅŸ County Romania bgiu.jpg|thumb|The Wallachian Plain, in the southern part of ArgeÈ™ County ArgeÈ™ CountyFile:Festos - Valley of Messara 2.jpg|thumb|View of Messara from the hill of Phaestus, Greece.]]File:Western Sydney (Badgerys Creek) Airport site - Anton Rd.JPG|thumb|Cumberland Plain bushland in Western Sydney Western SydneyFile:TaieriPlain.jpg|thumb|Looking southeast across the Taieri Plain, Otago, New Zealand New Zealand