Geophysical Investigations at Archaeological Sites 38SU45, 38SU147, 38SU215, AND 38SU232, Poinsett Electronic Combat Range, Sumter County, South Carolina

A series of large area high data sample density geophysical surveys have been performed to discover and map historic and prehistoric archaeological components at the Poinsett Electronic Combat Range. Three prehistoric sites and one historic site totaling 14,000 square meters were surveyed. Resistivity, magnetic field gradient and ground penetrating radar surveys were performed. More than ten data samples per square meter were collected, processed and mapped. A number of historic and prehistoric features have been discovered and located for test excavation. The absence of well defined hearth and pit features in the data from the prehistoric sites as well as the unambiguous but spatially diffuse data from the historic site both suggest that the archaeological record at these sites has very low geophysical contrast with respect to the surrounding soil matrix. This may be due to a poor state of preservation of the archaeological record and/or an ephemeral (e.g. transient) initial occupation. A poor state of preservation is likely. The resistivity contrast (associated with pits) will be
low due to the presence of high acidity well leached soils, a combination which conspires to remove the low resistivity components typically found in pits. The magnetic contrast will be low due to the absence of iron oxides in these soils. Both these processes are further aggravated by the unconsolidated nature of the sands, bioturbation and the disturbance associated with plantation pine agriculture. Test excavation can confirm or correct these conclusions.