EVOLUTIONARY DEVELOPMENT, COLLAPSE, AND BACK-STEPPING OF A BARRIER ISLAND SYSTEM, CAPE HATTERAS NATIONAL SEASHORE (CHNS), NC

Major and rapid evolutionary change, in direct response to dynamic surface processes, is the constant in coastal systems. Thus, to unravel the complex surface geomorphology and ecology requires utilizing time slice analysis integrated with field mapping and subsurface data from remote sensing and vibracores. Type localities were delineated for detailed time slice analysis using aerial photography back to 1932. Each locality was mapped on the 1998 DOQQ's and ground-truthed with field mapping. These data were then extrapolated backwards through time to the older, georeferenced time slices. The interpretations were integrated with ground-penetrating radar data on land and seismic data in adjacent estuaries, and vibracores for stratigraphic analysis of sediment, fauna, and Pb²¹⁰, Cs⁶⁷, and C¹⁴ age dating.

The resulting barrier island synthesis 1) defined the geologic framework underlying each barrier segment, 2) interpreted the Holocene barrier evolution, and 3) evaluated the process dynamics that led to the modern barrier island systems. The combination of regional back-barrier morphology of paleo-Pamlico drainage system, paleotopography of underlying Pleistocene drainage valleys and interstream divides, small Holocene sediment volumes within specific barrier segments, and ongoing sea-level rise are causing the current collapse of numerous barrier segments. These barrier segments will continue to disintegrate into Pamlico Sound, with the barrier shoreline back-stepping across the Pamlico Embayment and reforming on the landward side within the next century or two if current processes continue at their present rate.