Microstratigraphic reconstruction of formation processes and paleoenvironments at the Early Pleistocene Cornelia-Uitzoek hominin site, Free State Province, South Africa

Abstract The Cornelia-Uitzoek fossil site has produced a large collection of bones, Acheulean artifacts and a Homo sp. tooth dated to ~1 million years ago. The faunal assemblage defines the Cornelian Land Mammal Age and is characterized by a number of extinct species of large mammals that reflect an open grassland environment. Bones were accumulated by hyenas, whereas artifacts appear to be chance inclusions, although they suggest human presence in the immediate surroundings. Previous studies established the absolute chronology of the site and a broad stratigraphic sequence. However, the sedimentary units identified in the field were not linked to specific formation processes, thus limiting the understanding of the depositional history of the site and its potential in reconstructing Pleistocene environments. Using a microgeoarchaeological approach based on infrared spectroscopy and micromorphology of sediments, we were able to determine the formation and post-depositional processes of the entire stratigraphic sequence, and to show that the site is characterized by alluvial sediments accumulated under different river flow regimes. Our results provide context to the faunal and lithic assemblages and are in agreement with existing paleoenvironmental data for the site.