Late Holocene Evolution of Currituck Sound, North Carolina, USA: Environmental Change Driven by Sea-Level Rise, Storms, and Barrier Island Morphology

The Holocene evolution of Currituck Sound, North Carolina, is investigated using geological data and a hydrodynamic model to understand how this depositional basin changed in response to sea-level rise and regional climate patterns. Five depositional units (one Pleistocene and four Holocene) are defined based on geophysical surveys, lithofacies, biofacies, and geochronological data. The earliest Holocene unit (ca. 5000 cal YBP) represents a midsalinity (10-25 parts per thousand) sand shoal above the transgressive ravinement surface. This unit is overlain, successively, by (1) a freshwater swamp forest deposit, (2) a relatively saline (25-35 parts per thousand) back-barrier estuarine deposit associated with increased inlet activity, and (3) a mid- to low-salinity (<10 parts per thousand) deposit that is typical of modern (post-1827) Currituck Sound, a back-barrier estuary with no inlets in the barrier island. Geomorphic reconstructions provided the boundary conditions input to hydrodynamically model tide and current patterns and to constrain the probable size and location of inlets. The evolution of this system depends on sea-level rise and barrier morphology, regional hydrological factors, and regional climatic conditions, which modulate storm impacts and inlet activity along the fronting barrier system. The late Holocene stratigraphy reflects climate variability also recorded in the sediments of Chesapeake Bay (to the north) and Pamlico Sound (to the south) and is consistent with an increase in tropical cyclone activity during the Medieval Climate Anomaly and subsequent decrease in tropical storm activity since ca. 500 cal YBP.