One of the oldest islands in this system is Caladesi Island, a classic example of a drumstick barrier. The north end of the island was separated from what is now Honeymoon Island as the result of the hurricane of 1921, which broke through Hog Island to form Hurricane Pass (Brame, 1976). Caladesi Island experienced considerable progradation at its southern end due to the entrapment of sediment downdrift north of Dunedin Pass throughout most of the history of the island. Numerous beach/dune ridges separate swales and ponds. Dunedin Pass closed in 1988, three years after Hurricane Elena removed the ebb-tidal delta and facilitated longshore transport across the mouth of the small and unstable inlet (Davis and Hine, 1989; Barnard, 1998). Since that time, the southern end of the island has experienced erosion, and considerable accretion has taken place on the north end.

Sediments that comprise the barrier/inlet system along this coast display little variety (Yale, 1997). Fine quartz sand dominates with carbonate skeletal debris and mud as subordinant constituents. Most sediments are distinctly bimodal, with a shell-gravel fraction and the sand fraction dominated by quartz with lesser amounts of fine carbonate skeletal material. Stratigraphically, Caladesi Island shows a sand-dominated series of lithofacies with a range of shell gravel and mud. Back-barrier facies that originated as washover deposits are bioturbated and contain a significant amount of mineral and organic mud. Shallow to intertidal shoals, beach, and dune environments are represented by clean sand and shelly sand. As progradation of beach/dune ridges took place with mangrove environments intercalated between them, the surface and near-surface sediments reflected the presence of mangrove environments.