The geoarchaeology of Buttermilk Creek, Bell County, Texas

Abstract

The geoarchaeology of low order streams in Central Texas is not well known. Central Texas is also an area of rapidly expanding commercial development. For these reasons, a geoarchaeological investigation of a first order stream in Bell County, Texas was conducted. Buttermilk Creek is a 13 km stream incised into limestone bedrock with a drainage basin size of 43 kM2 , a stream gradient of 8.5 m/km, and a sinuosity of 1.26. This project was undertaken with two objectives in mind-, to create a geoarchaeological site potential model for Buttermilk Creek alluvial landforms, and by association, for similar drainage systems, and to determine the geomorphic effects of changing climatic conditions on low order drainage systems. To accomplish these goals, field data focusing on terrace heights, and alluvium composition were collected and analyzed. The alluvial landforms within the study area were found to consist of five depositional terraces (including the modem floodplain), six alluvial units, and one Early Holocene paleosol, referred to as the Brown paleosol. These alluvial units correlated well with the alluvial units studied on the Fort Hood Military Reservation by Nordt. Most significant, was the revelation that the Royalty Paleosol and the Brown paleosol were discovered to be contemporaneous. By combining the chronometric data from Fort Hood with the sparse chronometric data from Buttermilk Creek, I was able to construct an alluvial history for Buttermilk Creek landforms. The geoarchaeological site model was also constructed using these data. Although archaeological sites from almost all cultural periods could possibly exist within Buttermilk Creek alluvial units, the overall archaeological potential for the preservation of such sites was determined flood hydrological regime existing in this valley today and in the past. In addition, most alluvial deposits are coarse and gravelly; therefore, sites found in these deposits are most likely in a secondary context and of low research value. However low the overall archaeological potential of this valley, the archaeological potential of individual alluvial deposits, such as the Early Holocene Roden alluvium, could be high.