Carolina bays are elliptical depressions concentrated along the Atlantic seaboard within coastal Delaware, Maryland, New Jersey, North Carolina, South Carolina, Virginia, Georgia, and northcentral Florida (Prouty 1952, Kaczorowski 1977). In Maryland, they are called Maryland Basins (Rasmussen and Slaughter 1955). Within the Delmarva Peninsula, they and other coastal ponds are also called Delmarva bays (Coleman nd).Other landform depressions, not widely accepted as Carolina bays, are found within the northern Gulf of Mexico coastal plain in southeast Mississippi and Alabama, where they are known as either Grady ponds or Citronelle ponds (Otvos 1976, Folkerts 1997). Carolina bays vary in size from one to several thousand acres. About 500,000 of them are present in the classic area of the Atlantic Coastal Plain, often in groups, with each bay invariably aligned in a northwest-southeast direction. The bays have many different vegetative structures, based on the depression depth, size, hydrology, and subsurface. Many are marshy; a few of the larger ones are (or were before drainage) lakes; 36 square km (14 square mile) Lake Waccamaw is an undrained one. Some bays are predominantly open water with large scattered pond cypress, while others are composed of thick, shrubby areas (pocosins), with vegetation growing on floating peat mats. Generally the southeastern end has a higher rim composed of white sand. They are named for the bay trees frequently found in them, not because of the frequent ponding of water (Sharitz 2003). Undrained, often circular to oval, depressions exhibiting a wide range of area and depth are also a very common feature of the Gulf of Mexico coastal plain within Texas and southwest Louisiana. These depressions vary in size from 0.4 to 3.6 km (0.25 to 2 miles) in diameter. Within Harris County, Texas, raised rims, which are about 0.65 m (2 ft) high, partially enclosed these depressions. In the scientific literature, they are known by a variety of names, including “pocks”, “pock marks”, “bagols”, “lacs ronds”, and “natural ponds” (Aronow nda, ndb).