Atlantic Plain

[1] The lands adjacent to the Atlantic coastline are made up of sandy beaches, marshlands, bays, and barrier islands.

The coastal Atlantic plain features nearly continuous barriers interrupted by inlets, large embayments with drowned river valleys, and extensive wetlands and marshes.

The relief at the land-sea interface is so low that the boundary between them is often blurry and indistinct, especially along stretches of the Louisiana bayous and the Florida Everglades.

[4] The Coastal Plain of the United States includes all or portions of the states of Alabama, Arkansas, Delaware, Florida, Georgia, Kentucky, Maryland, Massachusetts, Mississippi, Missouri, New Jersey, New York, North Carolina, Oklahoma, South Carolina, Rhode Island,[a] Tennessee, Texas and Virginia.

From the northeast, it begins on Cape Cod, Massachusetts and stretches to the southwest to South Padre Island, Texas.

The Coastal Plain features nearly continuous barrier islands interrupted by inlets, large embayments with drowned river valleys, and extensive wetlands and marshes.

[5] The Atlantic Coastal Plain includes the Carolina Sandhills region[6] as well as the Embayed and Sea Island physiographic provinces.

The Atlantic Plain is generally gently dipping undeformed Mesozoic and Cenozoic sediments, with the sedimentary wedge thickening toward the sea, reaching a maximum thickness of about 3 kilometers (10,000 ft) in the vicinity of Cape Hatteras, North Carolina.

[7] Despite being previously overlooked in research, the Atlantic Coastal Plain is now identified as a global biodiversity hotspot, with over 1500 endemic plant species, and ~70% habitat loss.