Out in the Open: A Geoarchaeological Approach to Open-Air Surface Archaeology in the Semi-Arid Interior of South Africa’s Western Cape

Southern African research into the behavioural evolution of Late Pleistocene human adaptability, flexibility, and innovation is typically pursued through the lens of rock shelter deposits. However, rock shelters only cover a very small, geographically specific area of the subcontinent, distorting our understanding of change in human-environment interaction and demography. While still under-represented and under-explored in regional syntheses, more studies are looking to open-air archaeology to fill this geographic void in Late Pleistocene research. These studies either pursue a landscape approach that prioritises spatial coverage, or site-bound excavation to maximise temporal control. However, few investigate the depositional and erosional phenomena involved in the formation of surface archaeology and its surrounding landscape. To rectify this disparity, this thesis explores the complex spatio-temporal relationship between surface archaeology and the formation history of Uitspankraal (UPK) 7 by combining multiple interdisciplinary methods from the Earth and archaeological sciences: randomised surface survey and sampling, geomorphometry, geophysical survey, granulometry, XRD analysis, OSL dating, artefact mapping, and assemblage composition and artefact condition analysis. UPK7 is located in the semi-arid Doring River valley and yields surface archaeology that implies occupation from the Still Bay to the Historic period. Results show that it is an eroding series of source-bordering dunes draped across a palaeoterrace and a hillslope of bedrock and colluvium. UPK7 formed through rapid but pulsed sediment accumulation over at least the last 80 ka, with periods of surface deflation and exposure that facilitated artefact redistribution. Despite the abundance of Late Pleistocene archaeology at UPK7, erosion currently outpaces deposition and deposit stabilisation. Erosion has accelerated in at least the last 5,000 years and especially within the last 300 years, suggesting feedback between Holocene aridification, an increase in oscillations between wet-dry conditions, and an increase in human-ungulate activity in the study area. Together these conditions have differentially erased younger deposits, exposing the consolidated Late Pleistocene sediment and the more ancient material it preserves. The visibility, spatio-temporal distribution, and preservation of UPK7’s surface artefacts reflect the locality’s topography, the timing of their discard and the duration and process of sediment accumulation and erosion. The spatial patterning and diversity of time-diagnostic and non-diagnostic artefacts is shown to correspond with the depositional age of their underlying substrate in areas where topographic conditions minimize or reduce the impact of surface runoff, but where sediment deflation persists. When artefacts are assessed at the scale of the archaeological epoch the spatial distribution of Middle Stone Age artefacts shows a significant association with the oldest deposit, Lower Red. The spatial distribution of Later Stone Age artefacts is significantly associated with Upper Yellow sediment, as opposed to the older Lower Red substrate and the younger Indurated Sand. The findings presented in this thesis caution against forming behavioural interpretations from spatial patterns in surface material without examining their post-depositional history and without forming an understanding of the coevolution of archaeological and landscape formation. This study underscores the need for incorporating a geoarchaeological approach into Late Pleistocene open-air research to improve southern Africa’s landscape-scale insight into greater Africa’s human behavioural evolution