MICROPALEONTOLOGICAL EVIDENCE OF HURRICANE STRIKES FROM THE MARSHES OF ONSLOW BAY, NORTH CAROLINA

Nine back barrier marshes from Onlsow Bay, North Carolina, were cored to a 3-m depth in search of paleohurricane deposits. Only two marshes, Alligator Bay and Tar Bay Landing, contained displaced marine foraminifers indicative of storm deposition. A total of ten storm layers, representing four storms, were recovered at Tar Bay Landing and sixteen storm deposits, representing five storms, were recovered at Alligator Bay. Radiocarbon analysis indicates these deposits were created during the last 1,500 years.

Foraminifers from the sediments directly above and below the sandy storm deposits indicate that the paleostorms were depositing marine and beach or dune sediment into a variety of marsh subenvironments and that preservation was not necessarily greater in the high marsh (lower bioturbation) subenvironment.

Considering the number of hurricane strikes to Onslow Bay in the last century (approximately one per decade), the paleostorm record preserved in the marshes from the last millennia is poor. The scarcity of storm deposits also suggests that sand layers enriched with displaced marine foraminifers may significantly underestimate the frequency of storms in the region and may be limited as a paleotempest proxy. The preserved layers probably represent storm deposits that were quickly buried, limiting bioturbation, and that derived their source material during larger storms which reworked a higher number of offshore indicative foraminifers.