Coastal Classification Atlas

Geologic Setting

The northwestern panhandle coast of Florida between St. Andrew Bay Entrance Channel and Perdido Pass consists of sandy mainland beaches, broad peninsulas, and narrow barrier islands. A sandy mainland shore with relatively high upland elevations extends from Panama City to near Destin. In places a low erosional scarp forms a prominent topographic feature landward of the beach and dunes. The uplands are dissected by water-filled drainages (small lakes) that locally form short, narrow barriers where the small lakes intersect the Gulf shore. The short narrow barriers are prone to washover by storm waves or incision by shallow channels that drain rainwater impounded in the small lakes. The upland is composed of Pleistocene sand deposits, which have acted as a source of sediment for the adjacent barrier islands. Between the mainland beaches and barrier islands are broad peninsulas that separate St. Andrew Bay and Choctawatchee Bay from the Gulf of Mexico. Narrow barrier islands (Santa Rosa Island and Perdido Key) form the Gulf shore west of Destin. The beach sand typically contains some 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.

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