Coastal Classification Atlas

Geologic Setting

The southwestern coast of Florida between Venice Inlet and Cape Romano consists of sandy beaches and narrow barrier islands. Two prominent physiographic features are the headlands at Venice and Naples where the Gulf shore and mainland meet. The headlands are composed of Tertiary sandstone and limestone, which resist erosion. The coasts north and south of the headlands are characterized by barrier islands of variable dimensions separated by tidal inlets of variable dimensions (Davis, 1994). The sand that makes up the beaches and barriers overlies a hard limestone platform that forms the adjacent continental shelf (Locker et al., 1999). The limestone is exposed on the shelf or covered by a thin veneer of sand and shell. The beach sand typically contains abundant broken shell material as a result of high production of mollusks in the clear warm water of the Gulf of Mexico and an absence of rivers that would supply additional sand. Shells and broken pieces of rock are also concentrated on some beaches by the offshore dredging and hydraulic pumping associated with beach nourishment projects, which are common along this coastal region.