2015 GSA Annual Meeting in Baltimore, Maryland, USA (1-4 November 2015)

Paper No. 150-5
Presentation Time: 2:40 PM


MURPHY, Laura R., Far Western Anthropological Research Group, Inc., 2727 Del Rio Pl, Davis, CA 95618, lauram@farwestern.com

The theoretical framework of geoarchaeology was shaped by the recognition that both soils and landscapes are dynamic open systems that require thorough understanding before locating archaeological sites and interpreting the archaeological record. Conceptual geoarchaeological assessments of the landscape are based on the premise that geologic controls “filter” the archaeological record creating predictable patterns and ages for buried soils within alluvial fills, whereby the potential for the presence or absence of archaeological deposits of certain ages can be predicted. In more highly erosive areas, the premise is that there is an inverse relationship between the volume of preserved sediment and the recommended intensity of subsurface reconnaissance. Both models explain how periods of erosion can lead to archaeological preservation bias, but they do not explain how these processes impact inferences made about hunter-gatherer behavior and demographics. Here, the Revised Universal Soil Loss Equation (RUSLE) is used to estimate average annual soil loss in an erosive study area in northwest Texas, where surface survey spanning five landform surfaces yielded 385 hearth features. Based on a new equation that estimates population based on erosion and hearth density, results show population rapidly expanding during the Middle Archaic and then steadily increasing through the pre-Contact period. This trend does not match the current radiocarbon frequency distribution from the study area, which suggests land-use intensification and population increases occur after the Middle Archaic. Thus, erosion is removing Archaic-aged hearths, which changes the interpretations about hunter-gatherer behavior in the study area. When we understand both the conceptual aspects of geomorphic filtering and the quantitative extent to which the archaeological record has been affected by erosion, we can make more substantiated conclusions about the archaeological patterns on the surface that inform us about human behavior.