Sand ramps or climbing dunes? : identification and palaeoenvironmental significance of aeolian deposits in the Southern Kalahari and Breede River valley, South Africa

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dc.contributor.advisorHolmes, Peteren_ZA
dc.contributor.advisorMeadows, Michael Een_ZA
dc.contributor.advisorThomas, Daveen_ZA
dc.contributor.authorTyson, Susan Jeanen_ZA
dc.date.accessioned2016-02-18T12:15:07Z
dc.date.available2016-02-18T12:15:07Z
dc.date.issued1999en_ZA
dc.descriptionBibliography: pages 120-128.en_ZA
dc.description.abstractThe study is primarily concerned with the identification of topographical dunes and their classification as either sand ramps or climbing dunes. Topographical dunes in two semi-arid regions, namely the southern Kalahari (a summer rainfall region) and the Breede River Valley (a winter rainfall region), were investigated. The study also evaluates the palaeoenvironmental significance of the topographical dunes and attempts a palaeoenvironmental reconstruction within the study regions. The two different rainfall regimes facilitated regional comparisons with respect to environmental change, most particularly during the Quaternary. The methodology comprises a review of current literature on topographical dunes, an examination of aerial photography to identify topographical dunes in South Africa and field work to ground truth the dunes. Field sampling, laboratory work (granular composition analysis, pH, conductivity and scanning electron microscopy) as well as statistical analyses (principal component and cluster analyses) were employed to assist in the palaeoenvironmental reconstruction. The results of the laboratory and statistical analyses do not reveal any obvious differences with respect to structure, particle size, pH, conductivity, chemical composition and the surface texture of the grains between, the different topographical dunes. The dunes comprise homogeneous quartz sand that was emplaced against topographical barriers as a result of aeolian processes. They are therefore classified as climbing dunes rather than sand ramps. Three optically stimulated luminescence dates were determined for a topographical dune from each study region. Samples from the Prynnsberg 2 dune in the southern Kalahari are dated to 100 years, and it is suggested that this is due to current reworking of the Kalahari sands from the extensive linear dune field and from the Orange River. It is proposed that the southern Kalahari topographical dunes are currently episodically active. From the Sandput dune in the Breede River Valley, three probable humid phases are identified: 762 kyr, 28.2 kyr and 9.9 kyr. These humid periods may be coupled with episodes of cooling, which supports results from previous studies. This finding has important implications for future climatic changes in the winter rainfall region of South Africa, implying that warming in the Western Cape may be associated with a decrease in precipitation. Lastly, a short historic overview of aerial photographs shows that topographical dunes are susceptible to human impacts in the form of agriculture, overgrazing, sand quarrying and through the construction of dams and weirs on rivers.en_ZA
dc.identifier.apacitationTyson, S. J. (1999). <i>Sand ramps or climbing dunes? : identification and palaeoenvironmental significance of aeolian deposits in the Southern Kalahari and Breede River valley, South Africa</i>. (Thesis). University of Cape Town ,Faculty of Science ,Department of Environmental and Geographical Science. Retrieved from http://hdl.handle.net/11427/17115en_ZA
dc.identifier.chicagocitationTyson, Susan Jean. <i>"Sand ramps or climbing dunes? : identification and palaeoenvironmental significance of aeolian deposits in the Southern Kalahari and Breede River valley, South Africa."</i> Thesis., University of Cape Town ,Faculty of Science ,Department of Environmental and Geographical Science, 1999. http://hdl.handle.net/11427/17115en_ZA
dc.identifier.citationTyson, S. 1999. Sand ramps or climbing dunes? : identification and palaeoenvironmental significance of aeolian deposits in the Southern Kalahari and Breede River valley, South Africa. University of Cape Town.en_ZA
dc.identifier.ris TY - Thesis / Dissertation AU - Tyson, Susan Jean AB - The study is primarily concerned with the identification of topographical dunes and their classification as either sand ramps or climbing dunes. Topographical dunes in two semi-arid regions, namely the southern Kalahari (a summer rainfall region) and the Breede River Valley (a winter rainfall region), were investigated. The study also evaluates the palaeoenvironmental significance of the topographical dunes and attempts a palaeoenvironmental reconstruction within the study regions. The two different rainfall regimes facilitated regional comparisons with respect to environmental change, most particularly during the Quaternary. The methodology comprises a review of current literature on topographical dunes, an examination of aerial photography to identify topographical dunes in South Africa and field work to ground truth the dunes. Field sampling, laboratory work (granular composition analysis, pH, conductivity and scanning electron microscopy) as well as statistical analyses (principal component and cluster analyses) were employed to assist in the palaeoenvironmental reconstruction. The results of the laboratory and statistical analyses do not reveal any obvious differences with respect to structure, particle size, pH, conductivity, chemical composition and the surface texture of the grains between, the different topographical dunes. The dunes comprise homogeneous quartz sand that was emplaced against topographical barriers as a result of aeolian processes. They are therefore classified as climbing dunes rather than sand ramps. Three optically stimulated luminescence dates were determined for a topographical dune from each study region. Samples from the Prynnsberg 2 dune in the southern Kalahari are dated to 100 years, and it is suggested that this is due to current reworking of the Kalahari sands from the extensive linear dune field and from the Orange River. It is proposed that the southern Kalahari topographical dunes are currently episodically active. From the Sandput dune in the Breede River Valley, three probable humid phases are identified: 762 kyr, 28.2 kyr and 9.9 kyr. These humid periods may be coupled with episodes of cooling, which supports results from previous studies. This finding has important implications for future climatic changes in the winter rainfall region of South Africa, implying that warming in the Western Cape may be associated with a decrease in precipitation. Lastly, a short historic overview of aerial photographs shows that topographical dunes are susceptible to human impacts in the form of agriculture, overgrazing, sand quarrying and through the construction of dams and weirs on rivers. DA - 1999 DB - OpenUCT DP - University of Cape Town LK - https://open.uct.ac.za PB - University of Cape Town PY - 1999 T1 - Sand ramps or climbing dunes? : identification and palaeoenvironmental significance of aeolian deposits in the Southern Kalahari and Breede River valley, South Africa TI - Sand ramps or climbing dunes? : identification and palaeoenvironmental significance of aeolian deposits in the Southern Kalahari and Breede River valley, South Africa UR - http://hdl.handle.net/11427/17115 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/17115
dc.identifier.vancouvercitationTyson SJ. Sand ramps or climbing dunes? : identification and palaeoenvironmental significance of aeolian deposits in the Southern Kalahari and Breede River valley, South Africa. [Thesis]. University of Cape Town ,Faculty of Science ,Department of Environmental and Geographical Science, 1999 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/17115en_ZA
dc.language.isoengen_ZA
dc.publisher.departmentDepartment of Environmental and Geographical Scienceen_ZA
dc.publisher.facultyFaculty of Scienceen_ZA
dc.publisher.institutionUniversity of Cape Town
dc.subject.otherEnvironmental and Geographical Scienceen_ZA
dc.titleSand ramps or climbing dunes? : identification and palaeoenvironmental significance of aeolian deposits in the Southern Kalahari and Breede River valley, South Africaen_ZA
dc.typeMaster Thesis
dc.type.qualificationlevelMasters
dc.type.qualificationnameMScen_ZA
uct.type.filetypeText
uct.type.filetypeImage
uct.type.publicationResearchen_ZA
uct.type.resourceThesisen_ZA
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