LATE HOLOCENE PALEOENVIRONMENTAL CHANGE IN THE GULL ISLAND--SALVO AREA OF PAMLICO SOUND AND THE NORTH CAROLINA OUTER BANKS

Lithologic, foraminiferal, seismic reflection, and ground penetrating radar (GPR) data are being used to reconstruct coastal paleoenvironmental change in the Gull Island-Salvo segment of Pamlico Sound and the North Carolina Outer Banks during the late Holocene. Eighteen vibracores were taken in the back-barrier estuarine environment on the shallow-water (<2 m) platform known as Hatteras Flats. The upper ~2 m of sediment are fine-grained, grey estuarine sands generally barren of foraminifera or contain only rare Elphidium excavatum. Underlying are approximately 2 m of muddy, sometimes fine to medium-grained, grey sands (between 2 to 5 m below sea level) which are generally continuous at that depth throughout the study area. The muddy sands contain moderate diversity foraminiferal assemblages dominated by Elphidium excavatum with several subsidiary species (e.g., Hanzawaia strattoni and Nonionella atlantica); such assemblages are found on the North Carolina inner shelf today. Similar assemblages are found at similar depth ranges in vibracores from the western margin of Pea Island, 25 km to the north, which have been radiocarbon dated at approximately 1000 years before present. The widespread distribution of inner shelf assemblages in the back-barrier estuarine environment suggests that either 1) a major storm driven overwash event (or events) occurred approximately 1000 years ago, or 2) the barrier island contained major open breaches at that time and normal salinity conditions extended into a water body that could have been described as Pamlico Bay rather than Pamlico Sound.