GEOARCHAEOLOGICAL APPROACHES TO CULTURAL RESOURCES MANAGEMENT IN THE MURDERKILL WATERSHED: DELAWARE BAY, MID-ATLANTIC USA

The Murderkill watershed, located in the center of the Delaware Bay coast, is experiencing some of the fastest environmental changes along the bay. In the time of first documented human occupation the regional sea level was 5-6 m lower than its current position and humans settled a fluvial landscape along the banks of the ancestral Delaware river and its tributaries. Continuous relative sea level rise driven by deglaciation and isostatic adjustment of the crust through the Holocene changed the environments from fluvial to estuarine. Smaller stream valleys were inundated, converted into embayments, and eventually filled up with tidal wetlands, while the main channel of the lower Delaware river became an estuary. These changes occurred at a slow rate allowing humans to adjust to new environmental settings. In recent decades dramatic losses of tidal marshes related to accelerated rate of sea level rise, erosion and anthropogenic changes to sediment supply have been reported. There are over 100 cultural resources documented in the watershed ranging from Late Archaic (ca. 4500BP) through the mid-19^th century; three are listed on the National Register of Historic Places and over 60% are indigenous pre-colonial occupations. Most of these cultural resources are under immediate threat of inundation, storm erosion and tidal flooding. The Island Field site, which is less than 200 meters away from an actively eroding shoreline and surrounded by salt marsh, is at risk of submerging in the near future and is vulnerable to storm surges. Other sites further inland on tidal tributaries are threatened by flooding or being converted into salt marsh. We apply a probabilistic approach to modeling sea levels using the Representative Concentration Pathway (RCP) climate scenarios consistent with IPCC AR5. Predictions can be visualized at the decadal level for specific sites.