Academic literature on the topic 'Landforms - South Africa'
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Journal articles on the topic "Landforms - South Africa"
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SEPPÄLÄ, MATTI. "Evolution of landforms in South Africa." Boreas 9, no. 4 (January 16, 2008): 320. http://dx.doi.org/10.1111/j.1502-3885.1980.tb00712.x.
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Boelhouwers, Jan C. "Periglacial landforms at Giant'S Castle, Natal Drakensberg, South Africa." Permafrost and Periglacial Processes 5, no. 3 (August 1994): 129–36. http://dx.doi.org/10.1002/ppp.3430050302.
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Heyns, Andries M., Warren du Plessis, Kevin M. Curtin, Michael Kosch, and Gavin Hough. "Analysis and Exploitation of Landforms for Improved Optimisation of Camera-Based Wildfire Detection Systems." Fire Technology 57, no. 5 (April 10, 2021): 2269–303. http://dx.doi.org/10.1007/s10694-021-01120-2.
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AbstractTower-mounted camera-based wildfire detection systems provide an effective means of early forest fire detection. Historically, tower sites have been identified by foresters and locals with intimate knowledge of the terrain and without the aid of computational optimisation tools. When moving into vast new territories and without the aid of local knowledge, this process becomes cumbersome and daunting. In such instances, the optimisation of final site layouts may be streamlined if a suitable strategy is employed to limit the candidate sites to landforms which offer superior system visibility. A framework for the exploitation of landforms for these purposes is proposed. The landform classifications at 165 existing tower sites from wildfire detection systems in South Africa, Canada and the USA are analysed using the geomorphon technique, and it is noted that towers are located at or near certain landform types. A metaheuristic and integer linear programming approach is then employed to search for optimal tower sites in a large area currently monitored by the ForestWatch wildfire detection system, and these sites are then classified according to landforms. The results support the observations made for the existing towers in terms of noteworthy landforms, and the optimisation process is repeated by limiting the candidate sites to selected landforms. This leads to solutions with improved system coverage, achieved within reduced computation times. The presented framework may be replicated for use in similar applications, such as site-selection for military equipment, cellular transmitters, and weather radar.
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Obalum, S. E., J. C. Nwite, J. Oppong, C. A. Igwe, and T. Wakatsuki. "Variations in selected soil physical properties with landforms and slope within an inland valley ecosystem in Ashanti region of Ghana." Soil and Water Research 6, No. 2 (May 30, 2011): 73–82. http://dx.doi.org/10.17221/17/2010-swr.
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One peculiar feature of the inland valleys abundant in West Africa is their site-specific hydrology, underlain mainly by the prevailing landforms and topography. Development and management of these land resources under the increasingly popular sawah (a system of bunded, puddled and levelled rice field with facilities for irrigation and drainage) technology is a promising opportunity for enhancing rice (Oryza sativa L.) production in the region. Information on the variations in selected soil physical properties as influenced by the prevailing landforms may serve as a useful guide in site selection. This is of practical importance since majority of the inland valleys are potentially unsuitable for sawah development and most farmers in the region are of low technical level. Three landforms (river levee, elevated area and depressed area) were identified within a sawah field located in an inland valley at Ahafo Ano South District of Ghana. Each of these landforms was topsoil-sampled along on identified gradient (top, mid and bottom slope positions). Parameters determined included particle size distribution, bulk density, total porosity and field moisture content. The soil is predominantly clayey. There were no variations in the particle size distribution among the slope positions in the river levee. Overall, the river levee had lower silt content than the elevated and the depressed landforms. The bulk density, total porosity, and gravimetric moisture content indicated relative improvements only in the depressed area in the order, bottom > mid > top slope. Irrespective of slope position, the three landforms differed in these parameters in the order, depressed > river levee > elevated. The sand fraction impacted negatively on the silt fraction and bulk density of the soil, both of which controlled the soil moisture status. Despite the fairly low silt content of the soil, the silt fraction strongly influenced the gravimetric moisture content (R<sup>2</sup> = 0.80). So too did the soil bulk density on the gravimetric moisture content (R<sup>2</sup> = 0.90). It is concluded that: (1) since the landforms more prominently influenced the measured parameters than the slope positions, the former should take pre-eminence over the latter in soil suitability judgment; (2) with respect to moisture retention, variations in silt fraction and bulk density of this and other clayey inland-valley soils should be used as guide in site selection for sawah development.
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Evans, Mary, Bridget Fleming, and Gillian Drennan. "Can the augmented reality sandbox help learners overcome difficulties with 3-D visualisation?" Terrae Didatica 14, no. 4 (November 30, 2018): 389–94. http://dx.doi.org/10.20396/td.v14i4.8654110.
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Research has shown that students have difficulties in understanding topographic maps and landforms associated with contour patterns and therefore have problems in reading and interpreting topographic maps and relating these 2-dimensional representa-tions to a real 3-dimensional environment. However, maps are a fundamental tool for understanding geographical concepts and solving geographical problems. Current research indicates that this is not uniquely a South African problem and various at-tempts have been made to address this problem such as the use of videos, models and fieldtrips – each with their own limita-tions and difficulties. Nevertheless, the ability to visualize in 3-dimensions from a 2-dimensional representation is an essential skill in understanding and interpreting topographical maps. To address the problem of 3-D visualisation, an augmented reality sandbox (AR-Sandbox) was introduced to a Geography classroom, to Grade 11 students at a Secondary school in Johannes-burg, South Africa. The aim of this study is to determine the effectiveness of using the AR-Sandbox to enhance the learning of – and improve the learner's performance – in mapwork, and thereby address the problems experienced with 3-D visualisation. The results of the pre-test and post-intervention test are presented and show that the AR-Sandbox is an effective tool for en-hancing an understanding of landscapes rather an improving performance in the construction of cross-sectional profiles.
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Çöltekin, A., V. Rautenbach, S. Coetzee, and T. Mokwena. "LANDFORM PERCEPTION ACCURACY IN SHADED RELIEF MAPS: A REPLICATION STUDY CONFIRMS THAT NNW LIGHTING IS BETTER THAN NW AGAINST THE RELIEF INVERSION EFFECT." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLII-4 (September 19, 2018): 101–6. http://dx.doi.org/10.5194/isprs-archives-xlii-4-101-2018.
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<p><strong>Abstract.</strong> Relief inversion effect is a perceptual phenomenon that leads to an inverted perception of convex and concave shapes. This perceptual inversion occurs in scenes where the shading/shadows act as the main depth cue. In visuospatial displays, such as shaded relief maps, the positioning of the shadows in the northern slopes, thus when light source placed broadly in south, mislead the cognitive system based on the ‘light from above prior’ assumption (Mamassian and Goutcher 2001). Thus, assuming the light must come from above, our mind creates an illusion, and we perceive the landforms incorrectly. To judge the 3D spatial relationships in terrain representations correctly, the relief inversion effect must be avoided. Cartographic convention against this effect is to place the light source at northwest (NW), whereas a recent study demonstrated that north-north-west (NNW), or even north yields more precise results (Biland and Çöltekin, 2016). Since this finding goes against decades of convention, to establish its validity further, we attempted replicating the results with a different sample in South Africa. In this paper, we present our findings, which broadly confirm that the NNW (or also N) is better than NW against the relief inversion effect.</p>
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Pánek, Tomáš. "Recent progress in landslide dating." Progress in Physical Geography: Earth and Environment 39, no. 2 (October 7, 2014): 168–98. http://dx.doi.org/10.1177/0309133314550671.
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Recent progress of dating techniques has greatly improved the age determination of various types of landslides. Since the turn of the 21st century, the number of dated landslides throughout the world has increased several fold and the introduction of modern dating methods (e.g. cosmic ray exposure dating) has enabled the dating of new landslide features and elements. Based on the analysis of >950 dated landslides (of which 734 have been dated since the year 2000), it is clear that the predominant traditional strategies have continued to rely on the radiocarbon method; however, there is a remarkable trend of using cosmic ray exposure techniques for dating both the accumulation (e.g. landslide boulders) and the depletion (e.g. landslide scarps) parts of landslides. Furthermore, an increasing number of slope failures is determined by a multi-dating approach, which enables the verification of particular dating methods. Although coherent regional landslide chronologies are still relatively scarce in comparison with extensive databases of fluvial, glacial and/or eolian landforms, they offer important insights into temporal landslide distribution, long-term landslide behavior and their relationships with paleoenvironmental changes. The most extensive data sets exist for the mountain areas of North America (Pacific Coast Ranges), South America (Andes), Europe (Alps, Scottish Highlands, Norway, Carpathians and Apennines), the Himalaya-Tibet orogeny and the Southern Alps of New Zealand. Dated landslides in the plate interiors are lacking, especially in South America, Africa and Australia. Despite the fact that some dating results are well correlated with major regional and continental-scale changes in the seismic activity, moisture abundance, glacier regimes and vegetation patterns, some of these results contradict previously established straightforward hypotheses. This indicates the rather complex chronological behavior of landslides, reflecting both intrinsic (e.g. gradual stress relaxation within a rock mass) and external factors, including high-magnitude earthquakes or heavy rainfalls.
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Cullum, Carola, Gary Brierley, George LW Perry, and Ed TF Witkowski. "Landscape archetypes for ecological classification and mapping." Progress in Physical Geography: Earth and Environment 41, no. 1 (October 24, 2016): 95–123. http://dx.doi.org/10.1177/0309133316671103.
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We propose the use of archetypes as a way of moving between conceptual framings, empirical observations and the dichotomous classification rules upon which maps are based. An archetype is a conceptualisation of an entire category or class of objects. Archetypes can be framed as abstract exemplars of classes, conceptual models linking form and process and/or tacit mental models similar to those used by field scientists to identify and describe landforms, soils and/or units of vegetation. Archetypes can be existing taxonomic or landscape units or may involve new combinations of landscape attributes developed for a specific purpose. As landscapes themselves defy precise categorisation, archetypes, as considered here, are deliberately vague, and are described in general terms rather than in terms of the details that characterise a particular instance of a class. An example outlining the use of archetypes for landscape classification and mapping is demonstrated for granitic catenas in Kruger National Park, South Africa. Some 81% of the study area can be described in terms of archetypal catenal elements. However, spatial clustering of two classes that did not correspond to the archetypes prompted development of new archetypes. We show how the archetypes encoded in the map can be used to frame further knowledge in an ongoing, iterative and adaptive process. Building on this, we reflect on the value of vagueness in conservation science and management, highlighting how archetypes that are used to interpret and map landscapes may be better employed in the future.
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Green, Paul F., Karna Lidmar-Bergström, Peter Japsen, Johan M. Bonow, and James A. Chalmers. "Stratigraphic landscape analysis, thermochronology and the episodic development of elevated, passive continental margins." Geological Survey of Denmark and Greenland (GEUS) Bulletin 30 (December 30, 2013): 1–150. http://dx.doi.org/10.34194/geusb.v30.4673.
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The continental margin of West Greenland is similar in many respects to other elevated, passive continental margins (EPCMs) around the world. These margins are characterised by extensive regions of low relief at elevations of 1–2 kilometres above sea level sloping gently inland, with a much steeper, oceanward decline, often termed a 'Great Escarpment', terminating at a coastal plain. Recent studies, based on integration of geological, geomorphological and thermochronological evidence, have shown that the high topography of West Greenland was formed by differential uplift and dissection of an Oligo-Miocene peneplain since the late Miocene, many millions of years after continental break-up between Greenland and North America. In contrast, many studies of other EPCMs have proposed a different style of development in which the high plateaux and the steep, oceanward decline are regarded as a direct result of rifting and continental separation. Some studies assume that the elevated regions have remained high since break-up, with the high topography continuously renewed by isostasy. Others identify the elevated plains as remnants of pre-rift landscapes. Key to understanding the development of the West Greenland margin is a new approach to the study of landforms, stratigraphic landscape analysis, in which the low-relief, high-elevation plateaux at EPCMs are interpreted as uplifted peneplains: low-relief surfaces of large extent, cutting across bedrock of different age and resistance, and originally graded to sea level. Identification of different generations of peneplain (re-exposed and epigene) from regional mapping, combined with geological constraints and thermochronology, allows definition of the evolution leading to the formation of the modern-day topography. This approach is founded particularly on results from the South Swedish Dome, which document former sea levels as base levels for the formation of peneplains. These results support the view that peneplains grade towards base level, and that in the absence of other options (e.g. widespread resistant lithologies), the most likely base level is sea level. This is particularly so at continental margins due to their proximity to the adjacent ocean. Studies in which EPCMs are interpreted as related to rifting or break-up commonly favour histories involving continuous denudation of margins following rifting, and interpretation of thermochronology data in terms of monotonic cooling histories. However, in several regions, including southern Africa, south-east Australia and eastern Brazil, geological constraints demonstrate that such scenarios are inappropriate, and an episodic development involving post-breakup subsidence and burial followed later by uplift and denudation is more realistic. Such development is also indicated by the presence in sedimentary basins adjacent to many EPCMs of major erosional unconformities within the post-breakup sedimentary section which correlate with onshore denudation episodes. The nature of the processes responsible is not yet understood, but it seems likely that plate-scale forces are required in order to explain the regional extent of the effects involved. New geodynamic models are required to explain the episodic development of EPCMs, accommodating post-breakup subsidence and burial as well as subsequent uplift and denudation, long after break-up which created the characteristic, modern-day EPCM landscapes.
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Jha, V. C., and S. Kapat. "Rill and gully erosion risk of lateritic terrain in South-Western Birbhum District, West Bengal, India." Sociedade & Natureza 21, no. 2 (August 2009): 141–58. http://dx.doi.org/10.1590/s1982-45132009000200010.
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It is a known fact that no part of the earth surface is free from threat.It applies to Birbhum District, West Bengal, Indian Lateritic Terrain also. The existing terrain is characterized by mainly climatogenetic processes. Though the impact of climate change is vital in the shaping of the lesser topographies in the study-area. The study-area is characterized by micro landforms e. g. rills, gullies, water falls, terraces, gorges type features and limestone topographic type features. The denudational processes are very significant in the area in general but the differential erosion is evident in particular. It resembles the topographies with the African and the Brazillian Highlands. This paper interprets the rill and gully erosion risk in the lateritic terrain and their consequences in regional sustainable development and environmental management
Dissertations / Theses on the topic "Landforms - South Africa"
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Smith-Adao, Lindie B. "Links between valley confinement, landforms and vegetation distribution in a semi-arid valley floor environment, Baviaanskloof, South Africa." Thesis, Rhodes University, 2016. http://hdl.handle.net/10962/953.
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Although a large body of international literature has advanced our understanding of river systems, a considerable amount of gaps exit in the knowledge of dryland systems. River systems reflect complex interactions between biophysical processes and patterns. Understanding how processes generate observed patterns and, in turn, how patterns influence processes is crucial to understanding river structure and function. It requires an interdisciplinary approach in both research and resulting applications. The aim of this thesis was to examine the relationship between valley confinement, fluvial style, valley floor morphology and vegetation in the semi-arid environment of the Baviaanskloof river catchment, South Africa. This interdisciplinary investigation used a mixed method approach that involved desktop analyses and field surveys to understand dynamics at multiple scales, from the whole catchment to local (site, reach and quadrat or sample plot) scales. The desktop analyses included historical rainfall patterns and climate extremes, aerial photograph time-series and remote sensing greenness indices, and the field surveys focussed on cross-valley landform profiles, groundwater depth levels, sediment size distribution and soil chemistry, and vegetation distribution patterns. Based on the integrative assessment of these techniques a framework was developed of the links between valley confinement, surface-groundwater interaction, hydrogeomorphic processes and landforms, vegetation and human activities. Study findings highlighted the fact that very strong links exist between these factors. In this semi-arid area water availability (groundwater and streamflow conditions) was the primary control on valley floor vegetation composition and patterning. One group of species was associated with the wetted channel reaches at confined and semi-confined valley settings, while the other was associated with dry bed channel reaches at unconfined valley settings. The analyses also indicated that the environmental variables which best explained the variation in vegetation at the differing geomorphic landforms were related to landform position (elevation and distance), sediment size (fine and coarse sand) and available phosphorus (i.e. human impacts). The different plants, in turn, also affected landforms through their influence on sediment erosion, transport and deposition. Specially, they build, maintained or modified geomorphic landforms at confined, semi-confined and unconfined valley settings across the valley floor. Valley confinement was a primary control influencing hydrogeomorphic processes and their associated landforms. Alluvial fans and terraces acted as critical additional controls at especially the unconfined valley setting. Implications for restoration efforts in the catchment included strategies that took cognisance of: active revegetation on floodplain surfaces related to former agricultural fields; channel switching associated with the highly dynamic and unpredictable nature of geomorphic features; unstable multi-thread braided channels in the unconfined valley setting; and the selection of representative monitoring sites.
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Kück, Karen Melody. "Periglacial features in the vicinity of Tiffindell Ski Resort, North East Cape Drakensberg, South Africa, and their implications for the development of the resort." Thesis, Rhodes University, 1997. http://hdl.handle.net/10962/d1005520.
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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.
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Hardwick, Devlyn. "A mass movement classification for the southern Drakensberg, South Africa." Thesis, 2013. http://hdl.handle.net/10539/12736.
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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.
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De, Villiers Stephanie. "The development of a spatial database for research into cryogenic processes and Landforms in Southern Africa." Diss., 2000. http://hdl.handle.net/2263/29963.
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The first publication on southern African geocryology in 1944 resulted in a recognition of the potential of cryogenic phenomena in establishing long-term climatic records in the region, leading to a substantial increase in publications and research. Cryogenic studies are concerned with the way frost-induced processes have modified, and continue to modify, the mountain regions of the subcontinent. However, problems exist in interpreting relict forms, while supportive evidence for glacial and periglacial hypotheses are lacking. Insufficient data regarding Quaternary cryogenic activity have resulted in contradicting qualitative interpretations of the palaeoclimate and poor spatial and temporal resolution. It is apparent that there is a need for a more rigorous approach in southern African cryogenic studies as well as a better understanding of relict phenomena and the palaeo-environment. For this purpose a database that acts as a supplementary source and a tool for GIS-based analysis, was compiled. In addition, several glossaries and indices were constructed. The main glossary is a first effort at explaining past terminology usage and providing a terminology basis specifically for current research in southern Africa. Through database manipulation, the spatial distribution of past and present cryogenic phenomena as found in southern Africa, was mapped and it was found that cryogenic features and processes cluster along the Main Escarpment and the Western Cape Mountains. It is not clear if this is the actual situation or whether it represents a bias in the areas investigated. Further, likely regions for glacial ice development and survival and regions for periglacial activity were determined. The extent of relict and contemporary cryogenic activity was also verified. Evaluation of available data indicates that the extent of the cryogenic palaeo-environment did not differ considerably from the current one. An improved understanding of the spatial distribution of both relict and current cryogenic phenomena was achieved. The database represents a contribution towards the reconstruction of the southern African Quaternary environment and supplements current knowledge on the subject. While not necessarily providing solutions to current research problems, the database, combined with the glossaries and indices, will be invaluable in future research and modelling of the Quaternary in southern Africa.Dissertation (MA)--University of Pretoria, 2007.
Geography, Geoinformatics and Meteorology
Unrestricted
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Roelofse, Tiani. "Mineralogy and geochemistry of clay sediments in pans of the Northern Cape Province, South Africa." Thesis, 2010. http://hdl.handle.net/10413/5355.
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This thesis reports the results of a mineralogical and geochemical study of pans situated in the
Northern Cape Province with special emphasis on the clay minerals. From east to west the
depth and size of the pans increase and associated with this increased maturity the abundance
of salt (halite and thenardite) and the quantity of green sediment are also enhanced.
Chemically the sediments are dominated by SiO2 that also dilutes Fe2O3, K2O, Na2O, Al2O3
and MgO (when associated with dolomite) concentrations. Authigenic calcite, dolomite,
analcime and loughlinite (Na-sepiolite) occur in some of the pans to the west and FTIR
spectrometry indicates that all the pans host glauconite and/or celadonite. However, smectite,
illite/smectite interstratification, kaolinite and/or chlorite and loughlinite only occur in some
pans. The glauconite and/or celadonite does not occur as discrete mineral grains, but forms
part of the fine-grained matrix common to all of the pans and no evidence of any precursor
minerals were observed. The pan environment appears to present a closed, saline setting that
is conducive for the direct precipitation of a mica with a chemical composition between that
of glauconite and celadonite. The influence of the water-table on the formation of the
glauconite and/or celadonite appears to be significant, as the highest abundance of salt is
invariably associated with the position in the profile where the sediment appears to reach its
most intense green colour. In the case of Koi Pan, the celadonite component of the solid
solution seems to increase as the green colour intensifies. Loughlinite in Koi Pan and Brak
Pan sediments also appear to be authigenic and it is suggested that it forms after precipitation
of low Mg calcite that leads to Mg enrichment of the system and consequent sepiolite
formation associated with minor dolomite. Thermoluminescence ages obtained from the Koi
Pan sediment range between 37ka and 48ka before present at a depth of ~120cm below the
surface, while for Brak Pan, at roughly the same depth, an age of between 110ka and older
than 150ka before present was obtained. This may suggest different sedimentation rates in the
pans or much younger ages and thus faster formation of glauconite and/or celadonite in Koi
Pan since it is suggested that the mineral is authigenic.Thesis (M.Sc.)-University of KwaZulu-Natal, Westville, 2010.
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Edwards, Ryan. "The origin and evolution of Dartmoor Vlei in the KwaZulu-Natal Midlands, South Africa." Thesis, 2009. http://hdl.handle.net/10413/8922.
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Dartmoor Vlei is a 42ha un-channelled valley-bottom wetland system located in the headwaters of
the Myamvubu River in the KwaZulu-Natal Midlands, South Africa. The wetland and its
catchment are entirely underlain by a large dolerite sill that forms the Karkloof escarpment and
plateau and the wetland terminates against a dolerite dyke ridge that has intruded into the sill.
Wetlands on the Highveld and KwaZulu-Natal Midlands are thought to arise due to the lateral
erosion of valleys upstream of resistant lithologies that impede vertical erosion. This is typical of
valleys where Karoo sediments occur upstream of resistant dolerite dykes. Such valley widening by
lateral planing is typically associated with actively migrating meanders. As a result, wetlands found
upstream of dolerite intrusions are generally located on floodplains characterised by actively
migrating meanders, extensive backswamps, ox bow lakes, alluvial ridges and clastic alluvial fill.
However, in contrast to these floodplain wetlands, Dartmoor Vlei has evolved into an unchannelled
valley-bottom wetland characterised by diffuse flow conditions, minimal channelled
flow, extensive peat deposits and a general lack of floodplain features.
Coring within the wetland has established that the sedimentary fill of the wetland generally
comprises upward fining sequences of sediment characterised by sands and gravels near the valley
floor that grade into fine organic-rich silt sediments and peat at the surface. These findings
confirmed that the wetland has evolved from a floodplain wetland characterised by laterally
migrating meanders to a valley-bottom wetland characterised by discontinuous streams and peat
accumulation. Coring also established that the wetland is predominantly underlain by residual
saprolite that extends to depths in excess of 7m. The occurrence of a large discontinuity between
the residual saprolite and fresh dolerite surfaces underlying the toe of the wetland indicated that the
residual saprolite surface has sagged relative to the fresh dolerite and dolerite dyke at the toe of the
wetland over time. Chemical and mineralogical analyses of fresh dolerite and residual clay within
the valley confirmed that the chemical transformation of the dolerite bedrock into residual clay has
resulted in both volume and thickness losses in the weathered dolerite sill mass. This has in turn
resulted in the sagging of the valley floor and the wetland surface over time. These findings
provide an explanation for the extremely low energy conditions of Dartmoor Vlei and explain why
the wetland did not evolve in the same fashion as other wetlands in a similar geological and
geomorphological setting. The extensive chemical weathering of the dolerite sill underlying the
wetland has been attributed to the extremely long-time period that the soils within the wetland have
been saturated. The long-term saturation of soils within Dartmoor Vlei has been facilitated by the
formation and preservation of the African Erosion Surface on which Dartmoor Vlei is located.Thesis (M.Sc.)-University of KwaZulu-Natal, Westville, 2009.
Books on the topic "Landforms - South Africa"
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Grab, Stefan, and Jasper Knight, eds. Landscapes and Landforms of South Africa. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-03560-4.
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Olivier, Willie. Exploring the natural wonders of South Africa. Cape Town: Struik, 1996.
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Gavin, Whitfield, ed. Geological journeys: A traveller's guide to South Africa's rocks and landforms. Cape Town: Struik, 2006.
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Knight, Jasper, and Stefan Grab. Landscapes and Landforms of South Africa. Springer, 2015.
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Gibbard, P. L., and J. Ehlers. Quaternary Glaciations - Extent and Chronology, Volume 2: Part III: South America, Asia, Africa, Australia, Antarctica (Developments in Quaternary Sciences). Elsevier Science, 2004.
Find full textBook chapters on the topic "Landforms - South Africa"
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Cooper, Andrew. "South Africa." In Encyclopedia of the World's Coastal Landforms, 979–85. Dordrecht: Springer Netherlands, 2010. http://dx.doi.org/10.1007/978-1-4020-8639-7_177.
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Garland, Gerald G. "South Africa – Introduction." In Encyclopedia of the World's Coastal Landforms, 975–77. Dordrecht: Springer Netherlands, 2010. http://dx.doi.org/10.1007/978-1-4020-8639-7_176.
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Grab, Stefan, and Jasper Knight. "Landscapes and Landforms of South Africa—An Overview." In World Geomorphological Landscapes, 1–9. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-03560-4_1.
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Goudie, Andrew. "Aeolian Processes and Landforms." In The Physical Geography of the Mediterranean. Oxford University Press, 2009. http://dx.doi.org/10.1093/oso/9780199268030.003.0026.
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Certain parts of the Mediterranean lands are drylands— notably south-east Spain, the North African littoral, and parts of the Levant. This means that there is potential for aeolian processes to operate locally, especially where the vegetation cover has been depleted by human activities. Although water erosion is probably the most pervasive cause of land degradation in the Mediterranean lands (Chapter 20), susceptible soils in the drier portions of the region have been subject to accelerated wind erosion. This forms part of the phenomenon of desertification. Deforestation, high stocking levels of domestic animals, cultivation, and miscellaneous recreational pressures, have all helped to create this problem in North Africa (Sghaier and Seiwert 1993), the Levant (Massri et al. 2002) and in the semi-arid lands of Spain (Lopez et al. 2001). However, the GLASOD (Global Assessment of Soil Degradation) survey of wind erosion severity (Middleton and Thomas 1997: 32–3) suggests that at present, with the exception of parts of North Africa, the Levant, and Sicily, wind erosion severity is generally low in the Mediterranean region. In addition, the Mediterranean lands are in close proximity to the world’s greatest arid zone— the Sahara-Arabian belt—and so are subject to dust incursions from winds from that region: the ‘ghibli’ of Tripolitania, the ‘chili’ of Tunisia, the ‘khamsin’ of Egypt, and the ‘sirocco’ and ‘leveche’ of southern Europe. This has important geochemical implications (Kocak et al. 2004a, b). Knowledge of the dynamics of aeolian dust and sand transport comes from two main sources. The first of these is contemporary process monitoring, including data from dust traps, climatological stations, and remote sensing. The second is the long-term sedimentary record from such environments as caves, the sea-floor, lakes, bogs, and loess deposits. There are, however, problems with gaps in the stratigraphic record, and uncertainties and limitations with respect to developing accurate geochronologies. Atmospheric dust comprised of mineral aerosol derived by deflation of desert surfaces, much of it from the Sahara (Middleton and Goudie 2001; Goudie and Middleton, 2006), is a feature of the Mediterranean basin, and it impacts upon the environment in a number of ways (Goudie and Middleton 2001).