In situ shallow subsurface reflectance spectroscopy of archaeological soils and features: a case-study of two Native American settlement sites in Kansas

The results of in situ shallow subsurface reflectance spectroscopy surveys at two late 18th - 19th century Native American sites in Kansas contribute to a growing literature on the chemical characterization of anthropogenic features at archaeological sites. Near infrared and visible diffuse reflectance spectroscopy of known sub-soil features (hearths, storage pits, earthlodge walls, living surfaces, and defensive palisades) yielded characteristic signatures distinguishable from background spectra of adjacent locations. The spectra, obtained by insertion of a reflectance probe into the ground to depths up to 1 m at a series of locations, are further correlated with: electrical resistivity and magnetic gradiometry surveys; electrical conductivity and insertion force (soil compaction) contour plots; organic carbon, phosphorus, magnesium, and calcium spectra from analysis of core samples; and archaeological features recorded via excavation. The close spatial correlation of the spectroscopic data with known archaeological features supplements traditional topographic, surface, and subsurface geophysical survey methods by providing chemical information about ancient features and activity areas. The in situ recording of data has significant advantages over laboratory-based analyses.