A new geoarchaeology of Aboriginal artefact deposits in western NSW, Australia: establishing spatial and temporal geomorphic controls on the surface archaeological record

Surface deposits of stone artefacts are the most common feature of the Australian Aboriginal archaeological record, but they remain difficult for archaeologists to interpret. Among the many reasons is a lack of understanding of geomorphic processes that have exposed the artefacts at the surface. We describe research on the geomorphic environments in arid Australia from which we have developed a new geoarchaeological framework for describing and analysing surface artefact deposits. Optically Stimulated Luminescence dating of sediments upon which the artefacts currently rest demonstrates that the landscape, and the archaeological record it preserves, is spatially and temporally discontinuous. Exposure and/or burial of artefacts is controlled by geomorphic processes operating on timescales ranging from a few decades to thousands of years and spatial scales of tens to many thousands of square meters. These same processes, operating on similar scales, also determine whether or not artefact scatters are preserved in the contemporary landscape or in the sedimentary record of past landscapes, and hence whether or not they become part of the archaeological record. Models of settlement behavior in hunter-gatherer peoples that are largely derived from analysis of surface 'sites' must take account of these discontinuities.