Encyclopedic Entry

Plains near rivers are called flood plains. Photograph by Xi Luo, MyShot

Plains on Other Planets
Plains can be found on other planets. Mercury has large stretches of plains, and scientists have landed several probes on the boulder-covered plains of Mars.

Thundering Hooves
The Great Plains of North America once supported about 50 million bison, which are sometimes called buffalo. The bison roamed in vast herds, feeding on the prairie grasses. They were hunted to near-extinction in the 1800s.

A plain is a broad area of relatively flat land. Plains are one of the major landforms, or types of land, on Earth. They cover more than one-third of the world’s land area. Plains exist on every continent.

Grasslands

Many plains, such as the Great Plains that stretch across much of central North America, are grasslands. A grassland is a region where grass is the main type of vegetation.

In North America, temperate grasslands—those in places with warm summers and cold winters—are often called prairies. In areas with little rain and snow, short grasses grow. In areas that receive more rain and snow, tall grasses can grow 1.5 meters (5 feet) high. However, most tallgrass prairies have been plowed under and are now farmland or pasture.

The Great Plains have supported a wide variety of cultures for thousands of years. The so-called “Plains Indians” are actually more than two dozen tribes. Plains Indian tribes include Blackfoot, native to the Canadian province of Alberta; Arapaho, whose center today is in the U.S. state of Wyoming; and Kickapoo, many of whom live today in the Mexican state of Coahuila.

In Asia and eastern Europe, temperate grasslands are called steppes. Steppes usually do not receive enough rain for tall grasses and trees to grow.

Tropical grasslands are called savannas. Savannas exist in places that are warm throughout the year. They often have scattered trees. Savannas such as the Serengeti plains stretch across much of central Africa. They are also found in Australia, South America, and southern North America.

Not all plains are grasslands. Some, such as Mexico’s Tabasco Plain, are forested. Forested plains have different types of trees, shrubs, and other vegetation.

Deserts can also be plains. Parts of the Sahara, a great desert in North Africa, are plains.

In the Arctic, where the ground is frozen, plains are called tundra. Despite the cold, many plants survive here, including shrubs and moss.

Plain Formation

Plains form in many different ways. Some plains form as ice and water erodes, or wears away, the dirt and rock on higher land. Water and ice carry the bits of dirt, rock, and other material, called sediment, down hillsides to be deposited elsewhere. As layer upon layer of this sediment is laid down, plains form.

Volcanic activity can also form plains. Lava plains form when lava pushes up from below ground and flows across the land. The earth in a lava plain is often much darker than the surrounding soil. The dark earth is a result of the lava, mostly a dark-colored mineral called basalt, broken down into tiny particles over millions of years.

The movement of rivers sometimes forms plains. Many rivers run through valleys. As rivers move from side to side, they gradually erode the valley, creating broad plains.

As a river floods, it overflows its bank. The flood carries mud, sand, and other sediment out over the land. After the water withdraws, the sediment remains. If a river floods repeatedly, over time this sediment will build up into a flood plain. Flood plains are often rich in nutrients and create fertile farmland. The flood plain surrounding Africa’s Nile River has helped Egyptian civilization thrive for thousands of years.

Alluvial plains form at the base of mountains. Water carrying sediment flows downhill until it hits flat land. There, it spreads out, depositing the sediment in the shape of a fan. The Huang He River in China has created an alluvial plain that covers about 409,500 square kilometers (158,000 square miles). Because much of the sediment the Huang He carries is yellowish in color, it is also called the Yellow River.

Many rivers deposit their sediment in the ocean. As the sediment builds up, it might eventually rise above sea level, forming a coastal plain. The Atlantic Coastal Plain stretches along much of the eastern coast of North America. These broad underwater plains slope gently down beneath the water.

Abyssal plains are found at the bottom of the ocean. These plains are 5,000 to 7,000 meters (16,400 to 23,000 feet) below sea level, so scientists have a hard time studying them. But scientists say abyssal plains are among the flattest, smoothest places on Earth.

Vocabulary

Term Part of Speech Definition Encyclopedic Entry

abyssal plain

Noun

extensive, featureless region of the deep ocean floor.

alluvial plain

Noun

flat or gently sloping surface created by sediments left by flowing water.

Arapaho

Noun

people and culture native to the Midwest of the U.S.

Arctic

Noun

region at Earth's extreme north, encompassed by the Arctic Circle.

Encyclopedic Entry: Arctic

bank

Noun

a slope of land adjoining a body of water, or a large elevated area of the sea floor.

basalt

Noun

type of dark volcanic rock.

bison

Noun

large mammal native to North America. Also called American buffalo.

Blackfoot

Noun

people and culture native to the northern U.S. and southern Canada.

broad

Adjective

wide or expansive.

civilization

Noun

complex way of life that developed as humans began to develop urban settlements.

Encyclopedic Entry: civilization

coastal plain

Noun

low, flat land lying next to the ocean.

Encyclopedic Entry: coastal plain

continent

Noun

one of the seven main land masses on Earth.

Encyclopedic Entry: continent

deposit

Verb

to place or deliver an item in a different area than it originated.

desert

Noun

area of land that receives no more than 25 centimeters (10 inches) of precipitation a year.

Encyclopedic Entry: desert

dozen

Noun

a group of 12.

erode

Verb

to wear away.

extinction

Noun

process of complete disappearance of a species from Earth.

farmland

Noun

area used for agriculture.

fertile

Adjective

able to produce crops or sustain agriculture.

flood plain

Noun

flat area alongside a stream or river that is subject to flooding.

Encyclopedic Entry: flood plain

forest

Verb

to cover with trees and other vegetation.

grass

Noun

type of plant with narrow leaves.

grassland

Noun

ecosystem with large, flat areas of grasses.

Great Plains

Noun

grassland region of North America, between the Rocky Mountains and the Mississippi River.

herd

Noun

group of animals.

Kickapoo

Noun

people and culture native to the southern U.S. and northern Mexico.

landform

Noun

specific natural feature on the Earth's surface.

Encyclopedic Entry: landform

lava

Noun

molten rock, or magma, that erupts from volcanoes or fissures in the Earth's surface.

lava plain

Noun

large, flat piece of land created by lava spreading out evenly across a region.

mercury

Noun

chemical element with the symbol Hg.

mineral

Noun

inorganic material that has a characteristic chemical composition and specific crystal structure.

moss

Noun

tiny plant usually found in moist, shady areas.

mountain

Noun

landmass that forms as tectonic plates interact with each other.

mud

Noun

wet soil.

nutrient

Noun

substance an organism needs for energy, growth, and life.

Encyclopedic Entry: nutrient

pasture

Noun

type of agricultural land used for grazing livestock.

plain

Noun

flat, smooth area at a low elevation.

Encyclopedic Entry: plain

Plains Indian

Noun

one of many people and cultures native to the Great Plains in North America.

planet

Noun

large, spherical celestial body that regularly rotates around a star.

Encyclopedic Entry: planet

plow

noun, verb

tool used for cutting, lifting, and turning the soil in preparation for planting.

prairie

Noun

large grassland; usually associated with the Mississippi River Valley in the United States.

Encyclopedic Entry: prairie

probe

Noun

spacecraft designed to study part of the solar system and send information back to Earth.

province

Noun

division of a country larger than a town or county.

Encyclopedic Entry: province

region

Noun

any area on the Earth with one or more common characteristics. Regions are the basic units of geography.

Encyclopedic Entry: region

relatively

Adverb

in comparison to something else.

rock

Noun

natural substance composed of solid mineral matter.

Sahara Desert

Noun

world's largest desert, in north Africa.

sand

Noun

small, loose grains of disintegrated rocks.

savanna

Noun

type of tropical grassland with scattered trees.

sea level

Noun

base level for measuring elevations. Sea level is determined by measurements taken over a 19-year cycle.

Encyclopedic Entry: sea level

sediment

Noun

solid material transported and deposited by water, ice, and wind.

Encyclopedic Entry: sediment

Serengeti plains

Noun

grassland of the Serengeti ecosystem of Kenya and Tanzania.

snow

Noun

precipitation made of ice crystals.

soil

Noun

top layer of the Earth's surface where plants can grow.

steppe

Noun

dry, flat grassland with no trees and a cool climate.

Encyclopedic Entry: steppe

tallgrass prairie

Noun

plain where grasses grow up to 2 meters (6 feet) tall.

temperate grassland

Noun

flat, grassy area where there are seasonal differences in temperature and precipitation.

thrive

Verb

to develop and be successful.

thundering

Adjective

very loud.

tundra

Noun

cold, treeless region in Arctic and Antarctic climates.

valley

Noun

depression in the Earth between hills.

vast

Adjective

huge and spread out.

vegetation

Noun

all the plant life of a specific place.

volcanic

Adjective

having to do with volcanoes.

Credits

Media Credits

The audio, illustrations, photos, and videos are credited beneath the media asset, except for promotional images, which generally link to another page that contains the media credit. The Rights Holder for media is the person or group credited.

Writers

Kim Rutledge
Melissa McDaniel
Diane Boudreau
Tara Ramroop
Santani Teng
Erin Sprout
Hilary Costa
Hilary Hall
Jeff Hunt

Illustrators

Tim Gunther
Mary Crooks, National Geographic Society

Editors

Kara West
Jeannie Evers

Educator Reviewer

Nancy Wynne

Producer

Caryl-Sue, National Geographic Society

Sources

Dunn, Margery G. (Editor). (1989, 1993). "Exploring Your World: The Adventure of Geography." Washington, D.C.: National Geographic Society.

User Permissions

For information on user permissions, please read our Terms of Service.

If you have questions about licensing content on this page, please contact natgeocreative@ngs.org for more information and to obtain a license.

If you have questions about how to cite anything on our website in your project or classroom presentation, please visit our FAQ page.

Media

Some media assets (videos, photos, audio recordings and PDFs) can be downloaded and used outside the National Geographic website according to the Terms of Service. If a media asset is downloadable, a download button appears in the lower right hand corner (download) of the media viewer. If no button appears, you cannot download or save the media.

Text

Text on this page is printable and can be used according to our Terms of Service.

Interactives

Any interactives on this page can only be played while you are visiting our website. You cannot download interactives.