Source Determination of White River Group Silicates from Two Archaeological Sites in the Great Plains

Abstract

High-quality cryptocrystalline silicates from the Oligocene-age White River Group of the central Great Plains (referred to here as White River Group Silicates [WRGS]) were widely used prehistorically for chipped-stone tools. There are three known source areas for WRGS: Flattop Butte in northeastern Colorado, Table Mountain in east central Wyoming, and the White River Badlands of South Dakota. Specimens from these sources are often visually indistinguishable, making it difficult to specify the source of WRGS from nonquarry archaeological sites. Using a quantitative method—neutron-activation analysis—these sources were differentiated. The sources of WRGS in two Central Plains archaeological sites also were determined using this technique. The results show that the technique has important implications for studies of prehistoric mobility and for the refinement of cultural-historical affiliation.