Dr Ian Moffat
This research project will apply geophysical and geochemical techniques to rock shelter sediments from South Africa, Indonesia and northern Australia. Rockshelters provide the ideal setting to investigate human evolution as these often thick sedimentary accumulations provide a temporal record, facilitate dating and preserve abundant collections of lithic, faunal and other cultural material. They are also potentially rich repositories of environmental information; however traditional geoarchaeological methods of granulometry and soil micromorphology face significant challenges in contributing to our understanding of the environmental context of human evolution. The main limitation is that the specialised depositional environments found in these landforms means that the sedimentary processes are usually dominated by local events thus preventing regional correlation of the stratigraphy between sites. The small geographic extent of conventional archaeological excavations exacerbates this difficulty as it precludes testing of whether or not the revealed sections contain the most complete or conformable stratigraphy available within the site. Nonetheless, rockshelter sediments, particularly the allogenic component of the fine grained fraction, have been recognised as important indicators of past climate, and so there is significant potential to extract information from these key archives.
As part of this research, geophysical methods will be used to map bedrock topography and allow stratigraphic units to be correlated and mapped across the site. This information will allow critical evaluation of how well the units identified in the excavation represent the overall depositional conditions. Crucially, it will also evaluate if the base of the excavation is on roof fall or the true base of the shelter in order to determine if the full suite of archaeological and sedimentary materials has been revealed.
To complement the geophysical investigations, chemical and magnetic analysis of sediments in the laboratory is being used to elucidate changes in sediment provenance, erosion history, weathering intensity and soil formation that are driven by major reorganisations of regional climate. Because these techniques focus on regional scale processes they are insensitive to local changes in depositional conditions that can occur in an individual rockshelter. The chemical and magnetic results will allow correlation between archaeological sites and other climate archives.
ARC DECRA Grant #DE160100703