Paper No. 5
Presentation Time: 9:05 AM
GEOARCHAEOLOGY AND PALEOENVIRONMENTAL CONTEXT OF TWO DRAWS ON THE EASTERN ESCARPMENT OF THE SOUTHERN HIGH PLAINS OF TEXAS, USA
The north to south trending escarpment between the Southern High Plains and Rolling Plains in northwest Texas contains abundant springs, lithic resources, shelter, and plant and animal food sources that attracted hunter-gatherer groups. The larger goals of this study are to assess geoarchaeological potential for buried cultural material, and to provide a high-resolution multi-proxy paleoenvironmental data set to interpret bioclimatic change and hunter-gatherer landscape interaction. New pedologic, lithologic, and paleoenvironmental data are presented from the upper reaches of two draws on the edge of the escarpment: Spring Creek and Middle Creek. Grain-size, stable carbon isotope, and phytolith data, as well as radiocarbon ages determined on soil organic matter, are presented for localities in the upper reaches of Middle and Spring creeks. Results indicate two very different depositional and environmental histories, but both contain a late Pleistocene-middle Holocene record that has otherwise been mostly removed downstream. At Spring Creek, a series of laterally inset fills are identified and characterized, with ages spanning ~22,000-3000 14C yr B.P. (uncalibrated). At Middle Creek, buried soils in alluvium and lacustrine deposits ranging from ~10,800-2800 14C yr B.P. contain a well-preserved phytolith assemblage. Ongoing stable carbon isotope and phytolith analyses of the deposits are providing information about changes in plant communities through the late Pleistocene and Holocene. Initial results indicate that a C3 (cool/moist) plant community supported by ponds, marshes, and lakes persisted through the early and middle Holocene before gradually shifting to a C4 (warm/dry) grassland in the late Holocene. Phytolith results are compared to the stable carbon isotope record, and are used to determine the abundance of drought-resistant species and the types of plants that may have been used by hunter-gatherers.