20 Coastal Geomorphology (Posters)

Friday, 13 March 2009
1:30 PM - 5:30 PM

FUTURE EVOLUTION OF THE NORTHEASTERN NORTH CAROLINA AND SOUTHEASTERN VIRGINIA COASTAL SYSTEM BASED ON THE LATE QUATERNARY STRATIGRAPHIC RECORD

Paper number: 20-4
Program: Technical Sessions
Time: 1:30 PM – 5:30 PM

Authors

Abstract

An extensive lithologic, chronologic, and geophysical database for the coastal northeastern NC and southeastern VA late Quaternary section allows us to interpret the character and distribution of depositional environments associated with sea-level highstands. These paleo-environmental interpretations also allow us to project the future evolution of the coast as sea level continues to rise, the present barrier islands potentially disintegrate, and astronomical tidal influence increases within the estuarine system. Stratigraphic data indicate that: 1) before a continuous barrier-island system prevented open interchange with the Atlantic Ocean, earlier Holocene estuaries were influenced by astronomical tides to a much greater extent than they are presently; 2) extensive tidal flats existed across much of the area east of the Suffolk Shoreline c. 50 ka indicating substantial astronomical tides; 3)relative sea level was >5 m above present c. 80 ka and the region east of the Suffolk Shoreline was a marine system.

It is likely that the modern barrier islands will breakdown in the near future as a result of storms in concert with ongoing sea-level rise. This would substantially increase the role of astronomical tides in the back-barrier sounds changing the estuarine dynamics and character of fringing wetlands. Continued disintegration of the barrier-island system would result in increased astronomical tidal influence that will be amplified within upstream restricted embayments thus increasing development of muddy tidal flats. As sea level continues to rise, the pattern of southerly migration of the Chesapeake Bay mouth will flood across the interfluve with Currituck Sound. When sea level exceeds +5 m, the ocean shoreline will reoccupy the Suffolk Shoreline with the area to the east forming an open marine embayment.