Eastern Coastal Plain Studies
This project examines Pliocene and Pleistocene coastal deposits in outcrop, borehole and cores along the Atlantic Coastal Plain to establish the geologic history of natural climate variability in this region. Special emphasis is placed on two densely populated areas, the northern Chesapeake Bay and the lower Savannah River, both of which are characterized by coastal deposits overlain by inland aeolian deposits, though they differ in morphologic expression, composition, and structural complexity. AMS radiocarbon, optically stimulated luminescence, and Be-10 dating are used to establish geochronology; and remote sensing techniques, pollen assemblage data, and sedimentary texture analysis are used to correlate paleoclimate sequences across the Atlantic Coastal Plain. We are creating a reference record to enable finer scale paleoclimate signal resolution and comparison among terrestrial and marginal marine sediments along the Atlantic Coastal Plain.
Why is this research important?
A well-resolved chronostratigraphic framework and paleoclimate history of the Atlantic Coastal Plain is critical for coastal mappers to delineate areas of crustal deformation and for paleoclimate modelers to predict future climate and sea level changes. Collecting accurate and detailed data of natural variability along the U.S. east coast is the first step in understanding and addressing modern coastal zone concerns.
Project Leads:Marci Robinson, Ron Litwin
Project Team:Helaine Markewich, Milan Pavich (Emeritus), Joe Smoot (Emeritus), Nancy Durika
3 publications matching the specified parameters were found.
Litwin, R.J., Smoot, J.P., Pavich, M.J., Oberg, E., Steury, B., Helwig, B., Markewich, H.W., Santucci, V.L., and Sanders, G., 2013, Rates and Probable Causes of Freshwater Tidal Marsh Failure, Potomac River Estuary, Northern Virginia, USA: Wetlands, v. 33, no. 6, p. 1037-1061.
Markewich, H.W., Pavich, M.J., Schultz, A.P., Mahan, S.A., Aleman-Gonzalez, W.B., and Bierman, P.R., 2013, Geochronologic evidence for a possible MIS-11 emergent barrier/beach-ridge in southeastern Georgia, USA: Quaternary Science Reviews, v. 60, p. 49-75.
Swezey, C.S., Schultz, A.P., Gonzalez, W.A., Bernhardt, C.E., Doar III, W.R., Garrity, C.P., Mahan, S.A., and McGeehin, J.P., 2013, Quaternary eolian dunes in the Savannah River valley, Jasper County, South Carolina, USA: Quaternary Research, v. 80, p. 250-264.
Landscape Response to Quaternary Climate Change
This project focuses on age dating, palynology and geomorphology of late Quaternary sedimentary terraces along the lower Potomac River, along the Chesapeake Bay shoreline, and on the Delmarva Peninsula. Chronostratigraphy of estuarine and marine units deposited over the past 150ka is based on new 14C, 10Be and Optically Stimulated Luminesce (OSL) dating of organic material, soils and sands. Palynology shows millennial-scale cycles back to OIS6 (~150ka) are recorded in thick stratigraphic sections flanking the Potomac River. OSL dating of dunes identified using LiDAR shows the periglacial impact of the Laurentide Ice Sheet just prior to and during the last glacial maximum. The integration of dated transgressive units into stratigraphic and process models shows the importance of glacioisostatic adjustments (GIA) in the mid-Atlantic region. Quantifying past GIA rates interglacial-period subsidence and glacial-period uplift improves our understanding of present post-glacial subsidence its contribution to rates of relative sea level rise in the mid-Atlantic region. Freshwater marsh response to sea level rise is being investigated in Dyke Marsh near Washington, D.C.
Why is this research important?
Sea level rise is one of the most important issues on the densely populated east coast of the U.S. The rate of relative sea level rise in Chesapeake Bay is abnormally high due to a variety of processes, one of which is the ongoing collapse of the glacial forebulge produced by the Laurentide Ice Sheet during the last glaciation. A long pollen record is being used to reconstruct paleotemperature variations between the last glacial maximum and the last interglacial, for comparison with other Northern Hemisphere climate proxies.
The dating of periglacial intervals that include dunes and other geomorphic records of cold climate provides evidence for abrupt climate changes and the thresholds of landscape response to climate variations.