ADVANCES IN USING SOIL SURVEY DATA AS A PREDICTIVE TOOL FOR LOCATING DEEPLY BURIED ARCHAEOLOGICAL DEPOSITS IN STREAM VALLEYS OF THE MIDWEST, USA

In stream valleys of the U.S. Midwest, most of the existing record of prehistoric cultures is deeply buried. Therefore, there is a need for understanding the age and distribution of different landform sediment assemblages (LSAs) in these settings in order to adequately evaluate the landscape for buried archaeological materials. In this study, we show the applicability of the U.S. Department of Agriculture’s Natural Resources Conservation Service (NRCS) soil survey information available in the SSURGO database to (1) provide information on the spatial distribution and characteristics of different LSAs, and (2) determine the associated geologic potential for buried cultural deposits. We considered four factors in our assessment, including the age of sedimentary deposits, soil stratigraphy, depositional environment, and drainage conditions. Also, the relationship between certain soil series and specific members of the DeForest Formation, a Holocene lithostratigraphic unit, greatly facilitated the identification of the different LSAs. These data were used to develop a GIS-based buried-site potential model that was verified with data from a large volume of geoarchaeological research conducted throughout the region. The spatial scale of soil survey data, the subjective nature of soil mapping, and the ability to detect the presence or absence of buried soils were found to be important limitations. Nevertheless, our results show that NRCS soil survey data presented in the SURGO database can be useful in order to discriminate particular LSAs and appropriately evaluate buried-site potential.