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Plain

Expanse of land that is mostly flat

Wikipedia contributorsAdapted for Fathomly · View authors
5 min read
Source updated August 17, 2026
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In geography, a plain, commonly known as flatland, is a flat expanse of land that generally has few rapid or steep changes in elevation. Natural vegetation in plains can include prairies/grasslands, forests, savanah, tundra, and desert biomes, among others. 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.

01Description

A plain or flatland is a flat expanse of land with few rapid or steep changes in elevation. 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, 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 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. 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 may also be considered plains.

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.

Montane plains as seen in Horton Plains in Sri Lanka
Montane plains as seen in Horton Plains in Sri Lanka
Plain of Campidano, Italy
Plain of Campidano, Italy
A small, incised alluvial plain from Red Rock Canyon State Park (California)
A small, incised alluvial plain from Red Rock Canyon State Park (California)

02Types of plain

Depositional plains

The types of depositional plains include:

  • Abyssal plains, flat or very gently sloping areas of the deep ocean basin.
  • Planitia /pləˈnɪʃiə/, 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.
    • 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.
    • 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 as the bed of a lake.
  • Lava plains, 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 peneplains (almost plain) while plains formed from wind action are called pediplains.

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.

A flood plain in the Isle of Wight
A flood plain in the Isle of Wight
Po Valley, Carmagnola, countryside near the Po river, Italy
Po Valley, Carmagnola, countryside near the Po river, Italy

03Notable 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

Chengdu Plain, Sichuan
Chengdu Plain, Sichuan
Curry County, eastern New Mexico, on the North American Great Plains
Curry County, eastern New Mexico, on the North American Great Plains
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Sources and credits

This article is adapted from the Wikipedia article “Plain”, written by its contributors and licensed under CC BY-SA 4.0. Fathomly has changed the layout, removed citation markers, navigation and maintenance notices, and adjusted punctuation. This adapted version is shared under the same license. For references, see the original article.

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Flooded grasslands and savannas

Flooded grasslands and savannas is a terrestrial biome of the World Wide Fund for Nature biogeographical system, consisting of large expanses or complexes of flooded grasslands. These areas support numerous plants and animals adapted to the unique hydrologic regimes and soil conditions.

Flood-meadow

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