The project will examine the marine climate along the Atlantic Coast of the U.S. during three middle and late Pleistocene interglacial periods. The project will have two main goals: 1) produce detailed records of seasonal temperature ranges for the Virginia and South Carolina coasts during these interglacial periods, and 2) potentially improve the chronology of these transgressive events using strontium-isotope stratigraphy. The seasonal paleotemperature ranges will be calculated from the stable oxygen ( O) and carbon ( C) isotope profiles of fossil mollusk shells. Shell growth increments will be measured to identify periods of cessation of shell growth that truncate the isotope profiles. The growth increment data will also be used to assess an independent paleothermometer based on the geographic variation in ontogenetic growth trends. The timing of the Pleistocene transgressions onto the Atlantic Coastal Plain is the subject of an active debate over various interpretations of amino acid racemization and uranium-series dating methods. The strontium isotope analyses included in the proposed project should provide an independent set of data that addresses the geochronology of these units. All geochemical analyses will be performed on the same specimens that have been analyzed for amino acid racemization, so that the climatic and geochronologic information will be directly comparable.
