Reference work entry
Alabama has an embayed mainland coast with broad lagoons, including Mobile Bay and Perdido Bay, behind a sandy barrier island (Dauphin Island) that continues eastward as the Morgan Peninsula, extending to the Florida border ( Fig. 1.8.1). Much of the coastal plain is occupied by the dissected Upland Surface, underlain by late Pliocene deposits. Bluff-bounded, deeply incised wide valleys in the Mobile-Tensaw River system are associated with extensive valley-floor wetlands and a large marshy delta at the head of Mobile Bay. The narrow Holocene coastal plain east of Mobile Bay includes a beach ridge complex, interspersed with narrow lagoons, inlets, paralic lakes and marshes. The outer coast is bordered by a sandy barrier beach, 20 km long and 2–4 km wide, with dunes on the Morgan Peninsula. A large compound barrier spit at the mouth of the bay has narrowed the entrance to Mobile Bay.
KeywordsClay Depression Beach Silt Holocene
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