GEOARCHAEOLOGY OF THE BURNTWOOD CREEK ROCKSHELTER (14RW418), NORTHWEST KANSAS

The Burntwood Creek Rockshelter (site 14RW418) in northwestern Kansas is a large, amphitheater-shaped alcove formed in the Ogallala Formation, a late Miocene/Pliocene-age lithostratigraphic unit underlying the High Plains surface. In western Kansas, this unit consists of carbonate-cemented alluvium, and the Ogallala “caprock” forms the overhang of the Burntwood shelter. Burntwood Creek, a low-order stream, flows in an entrenched channel in front of the shelter, and a spring emanates from the back of the shelter. Recent archaeological test excavations in front of the shelter exposed a ~ 3 m-thick package of alluvial and colluvial deposits that have been slightly modified by pedogenesis. These deposits contain stratified Archaic and possibly Paleoindian cultural materials, including chipped stone and many fragments of bison- and deer-size bone. Seven major stratigraphic units were defined, with cultural features and artifacts concentrated in Strata 4, 5, and 6. Closer to the brow of the shelter, most of the sediments are products of roof fall and slope processes; there is no evidence of alluvium. Three buried soils are developed in the upper 1.5 m of a colluvial apron extending into the shelter, indicating that sediment was not continuously delivered to the colluvial footslope. Hence, the shelter has a very complex geomorphic history.

In this study, stratigraphic and sedimentological analyses are used to reconstruct the evolution of the rockshelter. Radiocarbon dating of cultural deposits (charcoal and bone) and soil organic matter (buried soils) will provide a numerical chronology for site formation. Also, ongoing phytolith and stable carbon isotope analyses are yielding information about late-Quaternary paleoenvironments that not only affected shelter-forming processes, such as sapping from spring activity, but influenced the subsistence strategies of prehistoric people who occupied the shelter and surrounding landscape.