Ph.D., Faculty of Science, University of the Witwatersrand, 2011 / Work on Sterkfontein cave deposits has generally focussed on clarifying the life histories of interned hominin remains. Less attention has been paid to the depositional context of the fossils and the specific stratigraphic processes involved in the formation of deposits, and their interaction within the cave system. Also lacking is an understanding of the complex processes influencing the distribution and integrity of the faunal and artefact assemblages. This research applied a broad-spectrum multidisciplinary approach to investigate a previously unexamined area of the caves with a particularly rich depositional history. The underground central deposits represent several infills of important fossil and artefact-bearing sediments. These sediments have accumulated into one of the deepest central areas of the Sterkfontein cave system creating a confluence area with a complex formation history. Three excavations (STK-MH1, STK-MH2 and STK-EC1) uncovered seven deposits. These deposits document a depositional history ranging from the earliest introduction of allogenic sediments (STK-MH1 T4), to the commercial exploitation of the caves through mining and tourism (STK-MH1 T1, STK-MH2). The stratigraphic sequence for the underground central deposits exhibits multiple formation processes including deposition (through numerous processes), erosion, collapse, diagenetic modification, deformation and displacement. The detailed stratigraphic history of these deposits was elucidated utilising sedimentological, fabric, stratigraphic, taphonomic and taxonomic analyses. As well as deciphering the complex formation history of this important area, this research attempted to identify the influence of cave sedimentation processes on faunal distribution and assemblage integrity. Faunal assemblages are prone to extensive modification caused by sedimentation and re-sedimentation processes mixing and distributing deposits through the caves. Varying sedimentological properties within fossil-bearing sediment gravity flows can cause the destruction of primary context taphonomic evidence, the concentration of fossils representing multiple stratigraphically distinct facies, and deposit-wide fossil distributions based on element size and shape. In addition to these processes, it was found that different skeletal elements change shape in different ways through breakage, thereby changing the specific mobility of the fossils and their potential distribution through the sediment body. Not identifying or not accounting for these post-depositional processes can lead to non-representative sampling, and to the misinterpretation of taphonomic and taxonomic data.

A dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Master of Science. Johannesburg, 2017 / During the Plio-Pleistocene, the Earth experienced a period of gradual cooling, leading to a decrease in atmospheric temperature and increased seasonality. This resulted in the aridification of large parts of Africa, and this is believed to have encouraged human evolution and innovation. Palaeoenvironmental analyses using sediment deposits as palaeoclimate proxies in the Cradle of Humankind have been used to understand the timing and intensity of this aridification by determining how changes in environmental conditions and seasonal cycles affected the South African landscape. These changes are recorded within the carbon and oxygen isotopic signatures of speleothems, which have precipitated within the Sterkfontein Caves system. The aim of this study is to understand the degree to which modern speleothems represent the modern climate and environment, and thereby deduce the reliability of speleothem deposits in the Sterkfontein Caves system as palaeoclimate proxies. Samples of modern speleothems were collected from different chambers of the Sterkfontein Caves, along with the collection of modern drip water samples bi-weekly over a period of 14 months. Oxygen and carbon stable light isotope analyses of these modern speleothem and drip water samples were used to obtain modern temperature, precipitation and vegetation data. These data were then compared to modern climatic and environmental records for atmospheric temperatures and precipitation from weather stations around the Sterkfontein Caves area. The δ13C trends produced from the modern speleothem samples reflected the current vegetation distribution in terms of C4 and C3 vegetation very well, while the temperatures calculated from the δ18O values of the modern speleothem and drip water samples displayed variations related to kinetic fractionation effects, rendering these data less useful in reflecting the current atmospheric temperatures. The δ18O values of the drip water samples, along with the measured drip rate reflected current precipitation seasonality, taking into account groundwater residence time and recharge rate. The conditions within the cave conducive to formation of the speleothems was well reflected by the pH and electro-conductivity values produced from the drip water samples. These values also provided further insight into the exterior climatic conditions. Overall, the carbon and oxygen stable light isotope data revealed patterns present in the modern speleothem and drip water samples, which could be further related to changes in local climate during the precipitation of these modern speleothems from drip water sources. This, to a certain degree, provides evidence of the reliability of speleothems in the Sterkfontein Caves system as suitable palaeoclimate proxies with regards to vegetation and precipitation interpretations, over a longer term scale and at higher sampling resolution. / MT 2018