THE GEOARCHAEOLOGICAL STUDY OF MOUND A, SHILOH INDIAN MOUNDS NATIONAL HISTORIC LANDMARK, HARDIN COUNTY, TENNESSEE

Archaeologists traditionally use earthen mounds to address questions of cultural complexity by estimating associated labor costs and inferring summit building size and structure. In the study of Mound A, at the Shiloh Indian Mounds National Historic Landmark (40HR7), this approach is expanded with the examination of the soils and sediments used in mound construction. The Shiloh Indian Mound archaeological site is a late prehistoric Mississippian mound center located in the lower Tennessee River Valley. It covers approximately 25 hectares and includes eight large mounds, of which Mound A, a roughly 7 m tall platform, is the largest. This large earthwork, the east side of which is rapidly eroding into the Tennessee River, was partially excavated as part of a salvage project conducted by the National Park Service Southeast Archeology Center. The geoarchaeological study of the Mound A excavations focused on the building materials and engineering principles used to construct the mound, and relied primarily on micromorphology and detailed field observation to identify construction stages. Analysis reveals a complex series of brightly and differently colored deposits and overlying facades used in various combinations. These strata are grouped into seven stages, with multiple substages, ranging in age from approximately AD 1000 to1250. Deposits of specific colors and textures were mined from nearby Cretaceous and Quaternary sediments. In several cases, specific colors and conditions were consistently created by mixing materials from several different source areas. Two types of inverted soil blocks were also used for mound construction to create a stable core and maintain steep slopes. There is little to no evidence that the mound stages were ever covered in vegetation, which suggests that these sediment surfaces would have required constant monitoring and maintenance. Thus geoarchaeological analysis indicates that much of the moundfill required significant investments in the selection, mixing, and application of materials to achieve specific and elaborate construction and aesthetic goals. This investment reflects cultural complexity, not in the control of a labor force, but in the specialized skills in the use of soil and sediments required to build and maintain the mound.