Combining Non-Invasive Geophysical Measurements With Soil Sampling to Evaluate 280 Years of Human Use At Wormsloe Historic Site.

Wormsloe Historic Site near Savannah, Georgia is a unique resource with an extensive history of human use.  There is evidence of Native American activity prior to European arrival and 280 years of documented use since colonization as a fortified settlement, working farm and home site. Traditional soil survey and sampling techniques were combined with non-invasive, geophysical imaging of selected sites to determine the legacy that past activities have on soils of this barrier island.  Historical maps were used to delineate post-colonization land use into heavily and lightly disturbed areas and to generate random sample points.  At each survey site, soils were described and samples were collected and analyzed for pH, C, N, and extractable cations.  Three distinctive areas identified from historical records and by survey point profile description or chemical analysis were selected for geophysical imaging using Electromagnetic Induction (EMI) and Electrical Resistance.  Images of subsurface features on the three sites were generated using a Dualem-2S EMI to a depth of 3 m and an AGI SuperSting R8 IP Resistivity meter to a depth of 2 m.  Results from the survey of heavily-disturbed and lightly-disturbed areas indicated small differences in soil profiles.  Preliminary comparisons of surface soil chemistry indicate large differences in pH, P and cation concentrations in highly disturbed areas compared to lightly disturbed areas.  Imaging of special interest areas identified several subsoil features that were candidates for detailed excavation and sampling.