PALEOTEMPESTOLOGICAL INVESTIGATION OF MIDDLETON POND, SC USA: A CALIBRATION OF THE SEDIMENTARY HISTORICAL RECORD

Three vibracores and seven gravity cores were extracted from Middleton Pond, Georgetown County SC, USA to correlate recent intense hurricane events with a three hundred year metorological record. This freshwater pond has proven to be an ideal site for a paleotempestological investigation based on the presence of multiple overwash events. Carbon/Nitrogen ratios, bulk density and magnetic susceptibility have been utilized to help determine marine versus terrestrial events, lithology and changes in paleoenvironment. Preliminary Cesium-137 data provide a sedimentation rate between 2.5mm/yr and 5 mm/yr. Correcting for compaction, this rate is consistent with deposition during intense storms that occurred during 1989 (Hugo), 1954 (Hazel), and unnamed storms of 1893 and 1885. Ongoing 210Pb and 14C analysis are underway to further define and individualize these events. To further assist in the identification of paleotempestology events, we will also present new results from a computer-based micro-structural analysis to resolve the lateral extent of flooding as a result of intense hurricane events. Thin-walled aluminum boxes (dimensions 15x3x0.5 cm) are used to take undisturbed soft sediment samples from selected intervals of the core face. These flat sub-cores are thin-sectioned after being impregnated with epoxy and freeze-dried following procedures of Francus (1997) and von Merkt (1971). Back-scattered electron images of the thin sections provide quantitative data on size, shape, orientation and packing of the grains.