STRATIGRAPHIC RELATIONSHIPS OF HOLOCENE PEAT-CONTAINING DEPOSITS OF THE WHITEWATER BAY REGION OF SOUTHERN FLORIDA

In this study sixty-six cores were examined from the southern tip of mainland Florida, extending from Florida Bay on the east coast through Cape Sable, Coot Bay, Whitewater Bay, and ending at the Gulf of Mexico. These cores were compared and correlated to develop several stratigraphic cross sections of the region, and selected cores were analyzed palynologically. Because some of the core information utilized in this study was based on previous studies unrelated to this work, core information for correlating purposes varied among sites, including not only the pollen and petrographic analyses from this study, but also unpublished field notes and microbotanical analyses from past published and unpublished research by Cohen and his students. Although the evidence from this study supports an overall transgressive relationship of lithologic units in this region, evidence from cores from the east coast, especially sections extending from Florida Bay to the southeastern edge of Whitewater Bay, strongly suggests a regression or stabilization of relative sea level towards the top of this sequence followed by continuation of relative sea level rise to the present. Palynological evidence from around the Coot Bay region strongly supports this contention, as mangrove and fresh water vegetation shift in concordance with the petrographic and other parameters. Stratigraphic evidence from areas in Whitewater Bay just behind Cape Sable indicate a blocking effect of the cape that caused thickening of freshwater peats immediately behind it but also provides support for one or more marine transgressive events in the upper part of the sequence followed by a regression or still-stand towards the top and then by continuation of sea level rise to the present. Stratigraphic evidence further supports the persistence of the Shark River Slough area as a conduit for marine waters and marine sediments into the area from the beginning of peat formation in this region to the present.