A thesis submitted to the Faculty of Science, University of the Witwatersrand, in fulfillment of the requirements for the degree of Doctor of Philosophy Johannesburg, 2012. / A variety of mass movement landforms occur in the southern Drakensberg, South Africa, and whilst a number of studies on individual landforms have been conducted, regional scale assessments of the Ukhahlamba Drakensberg Transfrontier Park have been relatively limited. Mass movement has been defined as the downward and outward movement of slope-forming material under the influence of a transporting agent such as water, air, ice or snow (Goudie, 2004). This includes landforms such as landslides, debris flows, terracettes, solifluction lobes and rockfall. Although two landslide risk assessments have been conducted in the region, one was site specific and focussed on shallow, translational slides (Bijker, 2001), whilst the other was at a much larger regional scale and focused on large palaeo-mass movements (Singh, 2008). Numerous international mass movement classifications have been developed over the years, and one of the primary aims of this research is to develop a classification for mass movement landforms within a southern African context. A number of mass movement landforms were identified, measured and mapped in the field to acquire a better understanding of how the landforms originate. This classification was then further adapted to facilitate the identification of mass movement landforms from orthophotos. Aerial photo interpretation techniques were used to map three terrace-type mass movement landforms and four shear-type mass movement landforms in the Garden Castle State Forest of the Ukhahlamba Drakensberg Transfrontier Park. A further level of detail was added to the classification by ascribing environmental conditions to the different landform types. A Geographic Information System was used to collate and generate spatial information which could be added to the landforms in the mass movement inventory. These were then analysed using univariate and multivariate statistical modelling. Histograms, as well as an area-weighted frequency distribution, were used to describe the landforms and then hierarchical partitioning was used to identify the environmental variables associated with each type of landform. One main environmental variable was identified for each type of mass movement. Logistic regression was then used to create probability maps for each type of landform. An average of 30% of the study area has a medium to very high likelihood of developing mass movements, although this percentage varies for each type, whilst rock movement deposits are predicted to occupy more than 80% of the study area. Gradient, altitude and lithology were selected most frequently by the statistical models as influencing landform distribution, whilst distance to a rock exposure had the strongest influence on the location of rock movement deposits. Aspect was selected least frequently by hierarchical partitioning which raises questions about the influence of aspect on valley asymmetry. Various models have been developed which describe slope development in the Drakensberg with reference to slope aspect, however the results of this study suggest that other environmental factors may be more important and that slope development is a complex process.

This thesis provides a description of the periglacial environment and features in the vicinity of Tiffindell Ski resort, on the slopes of Ben MacDhui (3001.2m.), the highest point of the East Cape Drakensberg, South Africa. Active and inactive periglacial features were located, mapped and described. Of particular interest were periglaciar slope deposits including gelifluction turf-banked lobes and stone lobes, and cryoturbation features including polygons and thufur. Local environmental factors, such as aspect, moisture, topography, soil texture and depth of freezing, appear to act as important controls on the spatial distribution of the periglacial features. Identification and quantification of periglacial processes in the regolith was investigated using temperature and soil moisture sensors coupled to dataloggers. Research was undertaken over a 16 month period from June 1995 to September 1996 so that comparisons between the winter conditions of 1995 and 1996 could be drawn. The Tiffindell area was observed to be characterised in the winter months by 'diurnal freezethaw days', as well as by 'ice days', 1996 experiencing colder temperatures than 1995. With more than 78% of the days from May to September 1996 being 'ice days', and simultaneously experiencing high soil moisture contents, freezing penetration to a depth of greater than 0.2m was observed to occur in the Tiffindell area, causing frost heave and gelifluction. The summer thaw of ice lenses that developed in the cold winter months caused surface movement downslope of gelifluction lobes of up to 39mm over an 18 month period, although movement declined rapidly with depth and was essentially restricted to the uppermost 130mm of the regolith. Other features such as sorted and non-sorted polygons and thufur were identified and found to be active under the present climatic conditions and depth of frost penetration at Tiffindell. Stone lobes were identified on the south and southeast-facing slopes at Tiffindell, but are apparently inactive under present climatic conditions. Their existence suggests the presence of severe seasonal frost in the past. The implications of the air and ground surface temperatures, and of seasonal frost penetration for the development of Tiffindell Ski resort were considered, and suggestions regarding their economic significance are presented.