The palynology of Upper Pleistocene and Holocene sediments from the eastern shoreline and Central Depression of St. Catherines Island, Georgia, USA

摘要

Sediment samples from the Hoke's Landing area of St. Catherines Island, Georgia, were analyzed for their pollen and spore contents, and were further analyzed for their clay mineralogy and time of deposition. Samples were retrieved from a core collected in July, 2013, and were recovered from a site lying near an early-twentieth-century oyster boiler on the eastern side of the island, the Hoke's Landing oyster boiler. The continuous core was more than 4.5m long, representing one of the longest continuous cores collected on the island. Palynological and radiocarbon analyses provide significant information concerning the Late Pleistocene and Holocene evolution of the island; one of the most ancient finite radiocarbon ages (31,990 +/- 230years BP) came from the Hoke's Landing site. Clay analyses indicate the presence of montmorillonite, kaolinite and illite, indicating sediment contributions from marine and terrestrial environments. Palynological data show that the freshwater fern Woodwardia grew in abundance at the site nearly 32,000years ago. Investigation of other strata from the island, and comparison with data derived from other locations on the Georgia coastal plain, were undertaken. Emphasis was placed on the timing and topographic extent of the Pleistocene sea level lowstand along the eastern seaboard of North America. The effects of the eastward migration of the Georgia coastal zone during the lowstand are preserved in sediments at Hoke's Landing, and provide a convincing new source of information concerning the nature of Pleistocene lowstand terrestrial communities in that region.