THE INFLUENCE OF CUSPATE FORELANDS ON REGIONAL CIRCULATION, SEDIMENT BUDGETS, AND CARBON CYCLING: AN OVERVIEW OF RESULTS

The Cape Hatteras and Cape Lookout National Parks encompass the best developed cuspate foreland shoreline in the world. Ongoing studies at Cape Lookout, North Carolina examine the formation of these features and their role in regional circulation, carbon sequestration, and sediment budgets. The mechanisms responsible for the development of cape-associated shoals and ultimately the formation of cuspate forelands are addressed through shoreline surveys, surface and sub-bottom surveys of the shoal, and a simplified complex-system model. Morphologic and volumetric changes of the subaerial cape and surrounding nearshore indicate an episodic sediment transport process wherein sediment is deposited as linear bars extending from the cape point. The orientation and position of the cape point are temporally dynamic, resulting in numerous linear bars that are abandoned on the shoal platform. We believe many of these linear bars are incorporated within the cape-associated shoal complex and moved seaward, however, shoreline surveys also suggest some sediment leaks around the cape point and is eventually deposited on an accreting spit along the northwest side of Cape Lookout. Rapid and constrained seaward flows of nearshore and estuarine waters along cape-associated shoals are revealed in satellite imagery as well as near-bottom current observations. We believe cuspate forelands may be an important conduit for exporting terrestrial and coastal nutrients/pollutants to the outer-shelf in passive margin settings. Preliminary results from Pb210 core-profiles also suggest the thick sandy beds which comprise the cape-associated shoal may filter a substantial level of terrestrial and marine carbon. The near-constant delivery of carbon- and oxygen-rich waters over these sandy shoals and the near-continual pulsing of pore water through the sand by waves create ideal conditions for carbon reduction.