The Coastal Plain is divided into the lower and upper plain. The upper Coastal Plain is then divided into the Aiken Plateau, the Richland Red Hills, and the High Hills of Santee. All of which are remains of land left by the constantly moving sea of the Pliocene. Six steep slopes at the edge of high ground and seven terraces create the surfaces of the lower Coastal Plains. These terraces represent the seven cycles of the receding ocean of two Pliocene, four in the Pleistocene, and one in Holocene.
Terraces are temporary oceans floors that go from the sea level rise and fall over time.
The mysterious elliptical depressions that are found along an 800-mile stretch of costal plain from Maryland to Florida and are scattered from the Fall Zone to the coast are of great interest to geologists, biologists, and ecologists because they provide important information about the environment that existed during the Quaternary Period. They also provide a natural laboratory that scientists can use to study rare and endangered plant and animal species. These bays are found all along the eastern coast of American but the majority of them are found in North and South Carolina which earned them the name Carolina Bays. These bays are large, shallow elliptical depressions, which have long axes that are aligned in the same general direction, northwest to southwest. The bays tend to range in size from three acres all the way to thousands of acres.