3. Electronic Theses and Dissertations (ETDs) - All submissions
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Item The sedimentology of the Jacovec, Sterkfontein(2018) Mavuso, Silindokuhle SiyabongaSince the first fossil discovery in the late 1800s Sterkfontein has become one of the most productive palaeoanthropological sites in the world. This cave network has produced abundant fossil material that has provided insight to Plio-Pleistocene ecology, environments and hominid behaviour. Although the site is rich in fossil material, various post-depositional processes that occurred over time have made the deposits very complex and difficult to decipher. At the centre of understanding this complex site, extensive geological work has been done to place the fossil material in the best possible context. This has led to the establishment of a cave stratigraphic framework, namely the Sterkfontein Formation, which has arranged fossiliferous deposits from some of the chambers in the Sterkfontein Cave System. However, some of the lowerlying chambers were not included within this stratigraphic framework and thus required investigation. After the discovery of a partial cranium of Australopithecus sp. in this cavern, the primary research focus was on taphonomy, palaeoecology, biostratigraphy as well as chronostratigraphy; minimal sedimentological work was undertaken. This research involved a sedimentological facies analysis in a lesser known chamber of the cave network, the Jacovec Cavern, which is one of the deepest caverns in the Sterkfontein Cave System. The examinations of the sediment yielded a detailed depositional history as well as provided the opportunity to test previously proposed karstification models. This provides a better comprehension for the formation and development of the Jacovec Cavern and its relation to the entire Sterkfontein Cave System. The observation of sediment halt (blockage from a palaeo-karst wall) suggested the presence of two depositionally independent chambers, namely the north western Main Jacovec Chamber and the newly-differentiated eastern (sediment-rich) Thulasizwe Chamber. Work in the Thulasizwe Chamber helped revise the proposed stratigraphy by identifying four distinct units and reconciling the previously-proposed reverse stratigraphy of the upper brecciated (Brown and Orange breccia) units. These four units begin with a basal slackwater (laminated) unit overlain by a debris flow unit followed by a fossiliferous Brown Breccia and, finally, a channel-derived Orange Breccia. The Main Jacovec Chamber contains two small sedimentary units whose depositional histories are harder to decipher. These sediments have been subject to a large degree of alteration (from both biotic and abiotic factors), which has led to the identification of cave access and phreatic stages. The lithology of the sediments (especially the presence of a distinct tuff seam) in both chambers has assisted in restricting the provenance of the sediments to localized deposits most likely coming from the south-southeast of the cave system. Furthermore, the presence of ghost rock remnants proved useful in providing a detailed karstification model (which suggests a long-lived stage of chemical dissolution before mechanical erosion and removal of cave earth) for the chamber and supports early works by Wilkinson (1985) of a deep phreatic network. This has implications for the stratigraphic interpretations on the cave system and sequence of filling.Item Faunal distribution in relation to rainfall patterns in the Kalahari Gemsbok National Park(2016) Maraschin, Nicoletta Maria RitaThis project investigates the influence that rainfall and temperature patterns have on mammal drinking patterns at an artificial waterhole in KGNP at Nossob. On a regional scale, this project investigates long-term rainfall and temperature trends over three/four decades, and in some instances the past 100 years, respectively for KGNP using climate records from weather stations located within the park and adjacent areas. This project makes use of KGNP census data to observe spatio-temporal distributions of large mammals in relation to rainfall (and to a lesser extent temperature) variability. Investigations assess whether relationships exist between faunal movement and distribution and rainfall volume and frequency. On a local scale, this project makes use of webcam images measured at 15-second intervals to establish mammalian drinking patterns and waterhole use over a short time scale (October 2012 – December 2014). The climate data for Twee Rivieren, Mata-Mata, Nossob and Upington reveal statistically significant increases in Tmax (av. 0.04°C) over the study period, whilst in summary, mean regional temperatures have increased by almost 1.6°C over the past 40 years. Rainfall patterns have revealed a north to south gradient in KGNP, where the northern and central parts of the park are becoming drier and the southern parts are becoming wetter. This demonstrates rainfall variability throughout KGNP over the period 2004 - 2013. This study established a positive relationship between faunal distributions and rainfall patterns within the park, showing that certain species are highly reliant on rainfall as a source of drinking water. It has been established that herbivore species are more reliant on the water trough during the dry season, when surface water is not available. However, there is an even spread of carnivore species water trough usage during the wet and dry season throughout the year. It has been established that during rainfall events exceeding ca. 30mm, faunal species prefer to utilise the natural surface water rather than the artificial waterhole at Nossob. Water trough usage under different temperature thresholds has revealed that groups of species (carnivores and herbivores) drinking patterns shift to either earlier or later in the day when temperatures increase, in order to avoid heat stress. Changing rainfall patterns could drastically cause water shortages, which will negatively affect the amount of available drinking water for mammals within KGNP. This study is important in contributing to an improved management of KGNP through providing a quantitative description of the relationship of mammal visitation at water troughs to the ambient climate. This is particularly valuable as climate change projections for the region suggest progressive drying. Water troughs will become an important source of moisture.