SOIL MINERALOGY AND GEOCHEMISTRY OF A CIVIL WAR-ERA SALT PRODUCTION FACILITY, SALTVILLE, SOUTHWESTERN VIRGINIA

A multi-disciplinary team from the fields of geology, archaeology, and remote sensing is investigating a Civil War-era military and industrial complex at Saltville, Virginia, where most of the Confederate salt supply was produced. Recent work has focused on analysis of soil mineralogy and organic and inorganic geochemistry at a known salt-making facility (a partially excavated brick furnace). A trench measuring 430 cm long and 150 cm in depth was dug for geoarchaeological work and soil sampling. The hypothesis was that heat emanating from the furnace had affected the bulk mineralogy of the soil units resulting in redder soils adjacent to the heat source and more yellow soils away from the heat source. A total of three vertical profiles (ranging from 125 to 150 cm depth) were studied to test the hypothesis and document spatial relationships between different soil units and their mineralogy. Thirty-one samples were analyzed via instrumental neutron activation, combustion, and titration, in order to measure bulk elemental concentrations (including major and trace elements), ferrous and ferric iron, total organic carbon and sulfur, and rare-earth elements (REEs). Ferrous iron shows an increase in samples farther away from the furnace and supports a heat-induced change of the iron oxidation state model for this site. Data also suggest a base-line contribution of ferrous iron from the in-situ, weathered Maccrady Shale - the parent lithology at the site. REE data (chondrite normalized) will be used for investigating source-rock relationships between REEs in the different soil units and the underlying weathered Maccrady Shale. Ongoing work also involves evaluation of possible relationships between the highly oxidized soils surrounding such furnaces and their spectral signatures recognizable by NASA's high-resolution AVIRIS (Airborne Visible/Infrared Imaging Spectrometer) flight sensors. We gratefully acknowledge the support of NASA Contract 961517 for this project.