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ENCYCLOPEDIC ENTRY
ENCYCLOPEDIC ENTRY

coastal plain

coastal plain

A coastal plain is a flat, low-lying piece of land next to the ocean

Grades

5 - 12+

Subjects

Earth Science, Geography, Geology, Physical Geography

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Morgan Stanley

A coastal plain is a flat, low-lying piece of land next to the ocean. Coastal plains are separated from the rest of the interior by nearby landforms, such as mountains.

In western South America, a large coastal plain lies between the Andes Mountains and the Pacific Ocean. In the United States, coastal plains can be found along the Atlantic Ocean and the Gulf of Mexico.

Coastal plains can form in two basic ways. Some start as a continental shelf, a flat piece of land located below sea level. When the ocean level falls, the land is exposed, creating a coastal plain. Sometimes, these coastal plains can extend far inland. Fossils of marine organisms have been found in the landlocked U.S. state of Kansas, for instance. Kansas was part of a vast coastal plain that formed when the Western Interior Seaway was forced to the Gulf of Mexico about 100 million years ago. The Western Interior Seaway was a large sea that split the continent of North America from what is now the Gulf of Mexico to the Arctic Ocean during the Cretaceous period.

A coastal plain can also develop when river currents carry rock, soil and other sedimentary material into the ocean. Layers of this deposited sediment build up over time, creating a flat or gently sloping landscape.

Fast Fact

Coastal Strawberries
The Oxnard Plain, a coastal plain in southern California, is home to some of the most fertile soil in the world. Some of the world's juiciest strawberries are grown there.

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Writers
Kim Rutledge
Melissa McDaniel
Santani Teng
Hilary Hall
Tara Ramroop
Erin Sprout
Jeff Hunt
Diane Boudreau
Hilary Costa
Illustrators
Mary Crooks, National Geographic Society
Tim Gunther
Editors
Jeannie Evers, Emdash Editing, Emdash Editing
Kara West
Educator Reviewer
Nancy Wynne
Producer
National Geographic Society
other
Last Updated

May 20, 2022

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