Plains are expansive, relatively flat areas of land covering over one-third of Earth’s terrestrial surface. Present on every continent, these major geographical features have influenced natural ecosystems and human civilizations globally.
Defining Plains
A plain is characterized by its generally flat or gently rolling terrain, showing little change in elevation over vast distances. While the term often implies complete flatness, plains can exhibit slight undulations or localized low hills. These landforms typically occur at relatively low elevations compared to surrounding mountains or plateaus, often forming lowlands along valleys or at the base of higher relief areas.
How Plains Form
Plains are shaped through various geological processes, often occurring over millions of years. One primary mechanism is erosion, where natural agents like water, wind, and ice wear down elevated landforms such as mountains and hills. The eroded material is then transported and deposited in lower-lying areas, contributing to the formation of flat surfaces.
Deposition plays a significant role, as sediments carried by rivers, glaciers, or wind accumulate over long periods. Rivers, for instance, deposit fine-grained sediments on their floodplains, building up fertile plains. Glaciers, as they move and melt, leave behind unsorted material known as till, forming till plains. Tectonic activity also contributes to plain formation, where some plains result from the uplift of ancient seabeds or the subsidence of land, creating extensive lowlands.
Types of Plains
Plains are diverse, categorized by their formation processes and geographical settings. Alluvial plains, also known as floodplains, are created by rivers depositing sediment over extended periods. These plains, such as the Indo-Gangetic Plain or the Mississippi Alluvial Plain, are often fertile due to the continuous replenishment of nutrient-rich soil by river floods.
Coastal plains are low-lying land areas adjacent to oceans or large bodies of water. They form from marine deposition, where sediments are deposited by ocean currents or from the uplift of continental shelves. Examples include the Atlantic Coastal Plain of North America and the coastal plains of Israel.
Interior plains are vast expanses of flat or gently rolling land situated far from coastlines, typically in the central parts of continents. These plains, like the Great Plains of North America, often formed from ancient depositional processes or extensive erosion.
Glacial plains result from the direct action of glaciers, either through the deposition of glacial till or outwash. Parts of the North European Plain exhibit characteristics of glacial plains, shaped by past ice sheets.
The Importance of Plains
Plains are important for both natural ecosystems and human societies. They are often agricultural lands due to their flat terrain, which facilitates mechanized farming, and their fertile soils, enriched by deposited sediments. Major agricultural regions worldwide, producing staple crops like wheat and corn, are found on plains.
Plains also support diverse ecosystems, particularly grasslands and prairies, home to various plant and animal species. For instance, the Great Plains of North America support hundreds of species of grasses, wildflowers, and wildlife such as bison and antelope.
Plains have historically been favored for human settlement and development due to their accessibility and ease of building infrastructure. Their level ground has facilitated the development of transportation networks, urban centers, and the growth of civilizations throughout history.