Glaciation/deglaciation is one of the most extreme and fundamental climatic events in Earth's history. The origin of the glacial-interglacial cycles has been explored for more than a century and the astronomical theory is now well established. However, the mechanism that links the astronomical forcing to the geological record in the Earth's climate system is poorly understood. In this thesis, aspects of the last glacial termination and the last glacial inception, are studied. First, the response of ocean's thermohaline circulation to changes in orbital geometry and atmospheric CO2 concentration in the last glacial termination is investigated using a coupled climate (atmosphere-ocean-sea ice) model. It is shown that the thermohaline circulation is affected by both orbital and CO2 forcing and the details of the mechanisms involved are explored. The climatic impact of changes in the thermohaline circulation is then investigated. It is revealed that the influence of changes in the thermohaline circulation on surface air temperature is concentrated in the North Atlantic and adjacent continents. It is also shown that this influence has its peak in winter rather than in summer. A dynamic ice sheet model is then globally and asynchronously coupled to the climate model. The relative importance of orbital and CO2 forcing in the mass balance of ice sheets is investigated using the coupled climate-ice sheet model. It is shown that CO2 forcing is of secondary importance to orbital forcing as the warming in eastern North America and Scandinavia due to CO2 forcing has its peak in winter, whereas that due to orbital forcing has its peak in summer. It is, nevertheless, concluded that the last glacial termination was initiated through increasing summer insolation and accelerated by a subsequent increase in atmospheric CO2 concentration. Second, the importance of subgrid topography in simulating the last glacial inception is investigated using the coupled climate model. The effects of subgrid elevation and subgrid ice-flow are incorporated in the model. Despite the use of high subgrid resolution, the coupled climate model fails to capture the last glacial inception. An atmospheric general circulation model is then used to explore the reasons for the failure, as well as the importance of changes in sea surface conditions and vegetation in simulating the last glacial inception. A realistic, geographic distribution of perennial snow cover and global net accumulation rate are successfully simulated when colder sea surface conditions than those of the present-day are specified. It is also shown that the effect of the vegetation feedback is large. It is revealed that changes in ocean circulation and vegetation are at least partly responsible for the complicated link between astronomical forcing and climate states during the glacial-interglacial cycles. As these two components play important roles, it is suggested that both components as well as ice sheet dynamics should be included in realistic paleoclimate simulations. / Graduate

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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.

by Lo Chuk-ching. / Thesis (M.Ph.)--Chinese University of Hong Kong, 1985 / Bibliography: leaves 92-96

Thesis (Ph. D.)--University of Canterbury, 2009. / Typescript (photocopy). One col. map in pocket. Includes bibliographical references. Also available via the World Wide Web.

Thesis (M.Sc.)--Memorial University of Newfoundland. / Typescript. Bibliography: leaves 185-197. Also available online.

Thesis (M.S.)--University of Akron, Dept. of Geology, 2009. / "August, 2009." Title from electronic thesis title page (viewed 10/21/2009) Advisor, John P. Szabo; Faculty readers, Linda Barrett, LaVerne Friberg; Department Chair, John P. Szabo; Dean of the College, Chand Midha; Dean of the Graduate School, George R. Newkome. Includes bibliographical references.

Thesis (doctoral)--Universität Zürich. / One folded ill. and 1 folded col. map laid in. Includes bibliographical references (p. 232-244).

Thesis (Ph.D.) - University of Queensland, 2004. / Includes bibliography.