Coastal plain

(geology) An extensive, low-relief area that is bounded by the sea on one side and by a high-relief province on the landward side. Its geologic province actually extends beyond the shoreline across the continental shelf; it is linked to the stable part of a continent on the trailing edge of a plate. Typically, it has strata that dip gently and uniformly toward the sea.

An extensive, low-relief area that is bounded by the sea on one side and by some type of relatively high-relief province on the landward side. The geologic province of the coastal plain actually extends beyond the shoreline across the continental shelf. It is only during times of glacial melting and high sea level that much of the coastal plain is drowned. See also Continental margin.

The coastal plain is a geologic province that is linked to the stable part of a continent on the trailing edge of a plate. The extent and nature of the coastal plains of the world range widely. Some are very large and old, whereas others are small and geologically young. For example, the Atlantic and Gulf coasts of the United States are among the largest in the world. (see illustration). In some areas the coastal plain is hundreds of kilometers wide and extends back about 100 million years. By contrast, local coastal plains in places like the east coast of Australia and New Zealand are only 1 or 2 million years old and extend only tens of kilometers landward from the shoreline.

Coastal plains of the United States.

The typical character of a coastal plain is one of strata that dip gently and uniformly toward the sea. There may be low ridges that are essentially parallel to the coast and that have developed from erosion of alternating resistant and nonresistant strata. These strata are commonly a combination of mudstone, sandstone, and limestone, although the latter is typically a subordinate amount of the total. These strata resulted from deposition in fluvial, deltaic, and shelf environments as sea level advanced and retreated over this area. Coastal plain strata have been a source of considerable oil and gas as well as various economic minerals. Although the coastal plain province is typically stable tectonically, there may be numerous normal faults and salt dome intrusions. See also Coastal landforms; Delta; Geomorphology; Plains.

A lowland area adjacent to the sea, which may have formed from marine sediments which have subsequently been revealed by a fall in sea level, as in the south-eastern coast of the USA.

The noun has one meaning:

Meaning #1: a plain adjacent to a coast

Coastal Plain in Albania

A coastal plain is an area of flat, low-lying land adjacent to a seacoast and separated from the interior by other features. One of the world's longest coastal plains is located in western South America. The southwestern coastal plain of North America is notable for its species diversity. The Gulf Coastal Plain of North America extends northwards from the Gulf of Mexico along the Lower Mississippi River to the Ohio River, which is a distance of about 500 miles (about 800 km). During the Cretaceous age, the central area of the United States was covered by a shallow sea, which disappeared as the land rose. Large fossilized aquatic birds called Hesperornis and Ichthyornis, found in western Kansas, indicate that the shallow sea was rife with fish. The coastal plain lying alongside the lower Mississippi River may be associated with a shallow sea which had existed 6 thousand years ago.

Some well-known coastal plains

• The Illawarra Plains, New South Wales, Australia
• The Swan Coastal Plain, Western Australia
• The Atlantic Coastal Plain, United States
• The Oxnard Plain, California, United States, near Los Angeles

See also

• Coastal prairie
• Field
• Flooded grasslands and savannas
• Flood-meadow
• Grassland
• Meadow
• Pasture
• Plain
• Prairie
• Rangeland
• Savanna
• Steppe
• Water-meadow
• Wet meadow
• Veld

External links

• Encyclopedia of Oklahoma History and Culture - Coastal Plains

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