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The Atlantic and Gulf Coastal Province differs from most other geomorphic provinces in North America in that it has a large suboceanic area (685 × 103 km2) in addition to its subaerial segment (1,166 × 103 km2; Table 1). The subaerial portion, usually referred to as the Coastal Plain*, extends from Long Island in New York (with outliers in Martha’s Vineyard and Cape Cod) to the Mexico border in Texas and includes all or part of 19 states. The suboceanic portion, which composes part of North America’s Continental Shelf, extends from the Canadian border south and west to the border with Mexico. The unifying character of this province stems mainly from a geologic history that has recorded alternating periods of submergence and emergence. Thus, all parts of the province have experienced coastal processes at one time or another, and most areas several times. However, over many parts of the province the surface expression of these processes has been destroyed or highly modified by erosion or burial. Most of the suboceanic portion of the province was subaerial as recently as 18,000 years ago, whereas parts of the subaerial portion of the Coastal Plain have not been submerged since the Cretaceous. The interface between the two divisions has been near its present elevational position for only some 5,000 to 6,000 years. During most of the province’s history, a number of geomorphic processes have been operative upon a relatively gently sloping surface consisting of rocks that generally increase in age upslope. In addition

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