T38 Sea-Level Changes from Minutes to Millennia (Posters)

Sunday, 19 October 2014
9:00 AM - 5:00 PM
Exhibition Hall C

EXTENSION OF THE LATE HOLOCENE SEA-LEVEL RECORD IN NORTH CAROLINA

Paper number: T38-10
Program: Technical Sessions
Time: 9:00 AM – 5:00 PM

Authors

Abstract

Future sea-level rise will dramatically affect coastal landscapes and populations. North Carolina (USA) is particularly vulnerable to sea-level rise because its low-lying coastal plain is expansive, has a low gradient and is economically important. Sea-level reconstructions provide a context for past and current trends as they relate to climate and oceanographic process, and insight into likely rates and magnitudes of future sea-level changes. North Carolina has extensive salt marshes which provide an excellent environment from which to produce relative sea-level reconstructions based on salt marsh foraminifera whose distribution is controlled by mean tide level.

We have collected foraminiferal assemblages of surface samples from two transects at Sand Hill Point (Cedar Island, North Carolina), which are combined with an existing training set (233 samples of paired observations of mean tide level and foraminiferal assemblages). This training set provides modern analogues for interpreting fossil assemblages. We apply a transfer function to foraminiferal assemblages preserved in a radiocarbon-dated core of salt-marsh peat at Sand Hill Point to produce a continuous, high resolution reconstruction of relative sea level during the late Holocene.

The salt marshes of northeastern North Carolina have a microtidal regime of less than 0.3m. In this tidal setting the ability of the transfer function method to improve the precision of sea-level reconstructions from the established age/altitude analysis is questionable. Therefore, we compare the transfer function effectiveness with an alternative classification method in a microtidal regime.

The new sea-level reconstruction from Sand Hill Point covers the past ~2200 years. It extends the existing record from nearby Tump Point, North Carolina by ca. ~1200 years using additional radiocarbon dates. We investigate whether local-scale processes affect patterns and rates of Holocene sea-level changes reconstructed elsewhere in North Carolina.