PALEOECOLOGICAL ANALYSES OF MODERN AND ANCIENT BARRIER ISLAND SEDIMENTS IN GEORGIA, MORE THAN 80,000 YEARS OF CHANGE AND MODIFICATION

More than three decades of continuous field and laboratory work have lead to the accumulation of substantial amounts of information concerning the probable origins and ecological evolution of a number of barrier islands on the coastal plain of Georgia. Very ancient barrier systems include the sand bodies associated with Trail Ridge, now located nearly 20 km west of the coastline. Analysis of strata from beneath Trail Ridge, as well as those associated with Reids and Bells Bluffs in northernmost Florida, Skidaway Island, near Savannah, Georgia, and St. Catherines Island has provided a wealth of paleoecological information. While megafossils such as clams (Mercenaria) and oysters (Ostrea) provide valuable paleoecological information, most of our data have been derived from palynology, the study of diverse types of plant microfossils. Our studies have focused mostly on pollen and spores, though freshwater dinoflagellates and other microscopic remains have also proven useful. The barrier islands and associated depositional environments accumulated sediments during conditions ranging from interglacial marine transgression peaks, at sealevels exceeding present conditions, to unusually low sealevels developed during the Last Glacial Maximum. These sediments contain microscopic remains of trees such as hickory (Carya), chestnut (Castanea) and hemlock (Tsuga) that provide clear evidence of both landscape and climate change over many thousands of years.