ABSTRACT
The Everglades-a huge freshwater marshland and, in large part, peatlanddeveloped in recent geologic time during a globally controlled convergence of both climatic change and sea level rise within a shallow bedrock trough located in south Florida. The recession of glaciers in northern North America at the end of the Pleistocene period and the change to a subtropical climate in south Florida provided both the abundant precipitation and the seasonal rainfall climate necessary for the generation of the Everglades wetland ecosystem. The rising sea level has undoubtedly retarded runoff and downward leakage out of the trough and helped to retain water within the Everglades basin. This, in turn, has allowed thick accumulations of peat (3-3.7 m) to develop within the deeper parts of the basin. The eastern coastal ridge, which was necessary to retain water within and in part defines the Everglades basin, owes its origin to marine geologic deposition which last occurred during the Sangamon interglacial age (about 125,000 years before present [YBP]), when sea level was up to 8 m above the present level. Repeated alterations between freshwater and marine conditions are revealed for interglacial times by the limestone rock record, with freshwater limestone layers occurring within the generally marine limestone sequence. Over the past 5000-6000 years, the southern end of the Everglades trough, open to Florida Bay and the Gulf of Mexico, has had the continually rising sea again move across it, into the Everglades and coastal salt marshes, transgressing over previously freshwater habitats.
