Showing items 441 - 460 of 648

Your selections:

Teacher-stress in South African state high schools

The development of the system of individual tenure for Africans: with special reference to the Glen Grey Act, c1894-1922

  • Authors: Ally, Russell Thomas
  • Date: 1985
  • Subjects: Cape of Good Hope (South Africa) -- History , Labor policy -- South Africa -- History , Black people -- Employment -- South Africa -- History , South Africa -- Politics and government -- History
  • Language: English
  • Type: Thesis , Masters , MA
  • Identifier: vital:2576 , http://hdl.handle.net/10962/d1003122 , Cape of Good Hope (South Africa) -- History , Labor policy -- South Africa -- History , Black people -- Employment -- South Africa -- History , South Africa -- Politics and government -- History
  • Description: The Glen Grey Act was promulgated in August 1894. The main provisions of the Act were for the survey into individual allotments of land held tribally and for a system of local self-government. Described by its originator, C.J. Rhodes, as a 'Bill for Africa, it was first applied to the district of Glen Grey and subsequently extended (in a piece-meal fashion) to a number of districts in the Transkei. The Act was introduced at a crucial stage in South Africa's history. During this period the country stood poised on the threshhold of a significant and far-reaching transformation. The South Africa of 'old', predominantly agricultural and rural was giving way to a 'new' South Africa, modern and industrial. At the centre of this development was the mineral discoveries of the 1860s and 1880s. The period of colonial conquest had also virtually been completed. Most of the hitherto independent African chiefdoms had either been broken up or were under European control. The most urgent problem which now faced the new rulers was devising a policy to govern the millions of black people over whom they had assumed responsibility. Of crucial concern was the creation of working class to minister to the needs of the developing economy. This task was made all the more difficult by the divisions which existed among the ruling groups at the time. To all intents and purposes the country was made up of essentially four independent and autonomous regions. Although the economic changes which were taking place would hasten the unification of the country, until that happened it was well-nigh impossible for a uniform 'native policy' to take shape. The inevitable consequence was the emergence of a number of regional responses to what was essentially a country-wide issue. As the unification of South Africa drew closer however these different regional responses began to vie with each other for supremacy at a national level. The Glen Grey policy then was the response of the Cape to the changes which were taking place in the country. As such, it drew much of its inspiration from the traditions which had developed in the Cape Colony. Its initiators did not however view it as only a regional policy. For them it had applicability to the whole country. It was therefore to be expected that they would attempt to 'sell' their policy to the rest of the country. In the end however it won few adherents outside of the Cape Colony and when Union became an established fact it bowed out to a policy favoured largely by the northern provinces. To be sure the Glen Grey system did linger on for a while in those districts where it had first been applied but it would not be long before it was to fall into official disapproval. While the Glen Grey Act was ushered in with much fanfare and vaunted expectations, its demise was silent and ignominous. The grandiose course which it had charted for the taking-in-hand of the 'native question' came to naught, as did the profound and far-reaching changes which it was believed the policy would inaugurate. The origins of this policy, its implementation and actual working, and the reasons why in the end it foundered and was abandoned will be the main themes of this thesis.
  • Full Text:
  • Date Issued: 1985

The ecology of Cactoblastis cactorum (Berg) (Lepidoptera : phycitidae) in relation to its effectiveness as a biological control agent of prickly pear and jointed cactus in South Africa

  • Authors: Robertson, Hamish Gibson
  • Date: 1985
  • Subjects: Insect-plant relationships Lepidoptera -- South Africa Cactus -- South Africa Weeds -- Biological control -- South Africa
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:5671 , http://hdl.handle.net/10962/d1005356
  • Description: The successful biological control of the shrub-like prickly pear Opuntia stricta Haworth in Australia by cactoblastis cactorum (Berg) was not repeated when C. cactorum, derived from the Australian population, was released in South Africa in the 1930's against the tree prickly pear Opuntia ficus-indica (L.) Miller. Resistance of the woody portions of o. ficus-indica to attack by C. cactorum was regarded as the main reason for the poor performance of C. cactorum in South Africa. C. cactorum also oviposits and feeds on Opuntia aurantiaca Lindley, which is currently South Africa's most important weed and which is also considered to be partly resistant to attack by C. cactorum. This study had three main objectives: (i) to compare the ecology and effectiveness of C. cactorum as a biological control agent on O. ficusindica and O. aurantiaca; (ii) to reassess why C. cactorum has not been as effective a biological control agent in South Africa as it has been in Australia; and (iii) to evaluate whether inundative release or the importation of new biotypes of C. cactorum from South America (where it is indigenous) might be feasible methods of improving its effectiveness as a biological control agent of O. aurantiaca in South Africa. All field work was undertaken at a site near Grahamstown in South Africa. The ecology and effectiveness of C. cactorum on O. ficus-indica and O. aurantiaca was assessed in terms of its oviposition behaviour, survival and feeding on these host plants. The proportion of C. cactorum eggs laid on O. ficus-indica and O. aurantiaca was similar and was influenced by the size, conspicuousness and condition of the host plant as well as by the proximity of the host plant to moth emergence sites. Factors affecting oviposition site selection on the plant are also considered. Life tables, compiled for a summer and a winter generation, showed that the survival of C. cactorum was greater on O. ficus-indica than on O. aurantiaca, mainly because higher egg predation by ants occurred on the latter host plant species. During the period of study, the population size of C. cactorum was reduced by a number of mortality factors, of which egg predation and the effects of low temperatures on fecundity were the most important. Although there was evidence of a partial, positive response by predatory ants to C. cactorum egg densities on plants, the extent of egg predation was also affected by other factors, particularly seasonal effects. C. cactorum destroyed a greater percentage of cladodes on O. ficu-indica than on O. aurantiaca, but even on O. ficus-indica it was unable to contain the growth of plants within the study area. C. cactorum larvae rarely killed the woody rooted cladodes of O. ficus-indica and O. aurantiaca and consequently whole plants were not often destroyed. The detrimental effects of host plant resistance, natural enemies and climate on the effectiveness of C. cactorum as a biological control agent all appear to be greater in South Africa than in most of the regions occupied by C. cactorum in Australia. A field experiment conducted at the study site showed that inundative release methods for improving the effectiveness of C. cactorum on O. aurantiaca are not feasible. The importation of biotypes of C. cactorum from South America that might be better suited for destroying O. aurantiaca infestations in South Africa, is also not a viable option. Results of a survey of a 218 ha area that is regarded as being heavily infested with O. aurantiaca, illustrate how this cactus species has been overrated as a weed problem. It is argued that the present strategy for O. aurantiaca control in South Africa is not based on sound economic or ecological criteria.
  • Full Text:
  • Date Issued: 1985

The effect of sewage on the distribution of seaweed at the Bats Cave east bank sewage outfall in East London, South Africa

  • Authors: Klenk, Theodore Charles
  • Date: 1985 , 2013-03-13
  • Subjects: Marine algae -- Dispersal -- South Africa -- East London , Sewage disposal in the ocean -- South Africa -- East London , Plants -- Effect of sewage on
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:4238 , http://hdl.handle.net/10962/d1004768 , Marine algae -- Dispersal -- South Africa -- East London , Sewage disposal in the ocean -- South Africa -- East London , Plants -- Effect of sewage on
  • Description: In order to determine which seaweeds were unable to survive in the stressed area and how far the effect of the effluent extended along the coast, various methods were applied and carried out over a two-year period between November 1982 and November 1984. Three major long-term studies took place. The first study was to determine the presence or absence of the seaweeds throughout (1) the entire study area and then (2) in areas broken up into sections with known distances from the outfalls. The second method involved statistical evaluations using point intersect methods and photography to produce information to determine species density, diversity, evenness, and to provide the information required to work with a number of ecological equations in the future. The third method incorporated a long-term survey on cleared plots in various sectors of the study area. The recolonization of the plots was recorded over a thirty-week period. (par. 1.1, p. 6-7)
  • Full Text:
  • Date Issued: 1985

The fishes of the Okavango drainage system in Angola, South West Africa and Botswana: taxonomy and distribution

  • Authors: Skelton, Paul H (Paul Harvey) , Bruton, M N , Merron, G S , Van der Waal, C W
  • Date: 1985
  • Language: English
  • Type: Text
  • Identifier: vital:15009 , http://hdl.handle.net/10962/d1019742 , ISSN 0073-4381 , Ichthyological Bulletin of the J.L.B. Smith Institute of Ichthyology; No. 50
  • Description: The publication of a new phase of research on the fishes of the Okavango drainage starts with this account which gives the valid names and broad distribution patterns of all species known from the system. Eighty species and subspecies are recognised, of which at least two (Parakneria fortuita Penrith; Serranochromis gracilis Greenwood) are endemic. Notes on early collections, synonymy, taxonomic status and distribution are given. New synonyms are recognized under Aplocheilichthys hutereaui (A. schalleri), Aplocheilichthys johnstoni (Haplochilus carlislei) and Ctenopoma multispinis (Ctenopoma machadoi) respectively. Recently published taxonomic changes are incorporated including two genera (Mesobola and Afromastacembelus), a species Serranochromis (Sargochromis) gracilis and the re-allocated Amphilius uranoscopus. The Zambezian Hemichromis species is re-identified as H. elongatus. A number of unresolved taxonomic problems are pointed out and certain dubious records are excluded from the checklist. The Okavango has a diverse fish fauna with tropical affinities. Many fish species are poorly studied. Man-induced threats to the continued natural functioning of this complex and dynamic system, especially large-scale water abstraction, overgrazing, deforestation and biocide spraying to eliminate tsetse fly, make it imperative that studies on the nature and role of the fishes are continued. , Rhodes University Libraries (Digitisation)
  • Full Text:
  • Date Issued: 1985

The geochemical stratigraphy of the volcanic rocks of the Witwatersrand triad in the Klerksdorp area, Transvaal

  • Authors: Bowen, Teral Barbara
  • Date: 1985 , 2013-03-14
  • Subjects: Lava -- South Africa -- Transvaal , Igneous rocks -- South Africa -- Transvaal , Geochemistry -- South Africa -- Transvaal
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:4932 , http://hdl.handle.net/10962/d1004932 , Lava -- South Africa -- Transvaal , Igneous rocks -- South Africa -- Transvaal , Geochemistry -- South Africa -- Transvaal
  • Description: This study lias initiated with the aim of identifying the existence of any geochemical criteria which may be used to distinguish between the various volcanic formations within the Witwatersrand triad. The Witwatersrand triad comprises three sequences: the Dominion Group at the base, the Witwatersrand Supergroup in the middle, and the Ventersdorp Supergroup at the top. It is underlain by Archaean basement rocks, and covered by rocks of the Transvaal sequence. The Dominion Group consists of the sedimentary Rhenosterspruit quartzite Formation at the base, overlain by a bimodal component of the Syferfontein Porphyry succession of lavas. Basaltic lavas are the major component of the Rhenosterhoek Formation, while the overlying Formation consists primarily of dacitic porphyries. Intercalations of one lava type within the other are common, however, so each formation is not the exclusive domain of only one lava type. The Witwatersrand Supergroup, a predominantly argillaceous and arenaceous sequence, contains two narrow volcanic horizons, one of wbich, the Jeppestown Amygdaloid (now Crown Formation), consisting of tholeiitic andesites, occurs in the study area. The overlying Ventersdorp Supergroup has, at its base, the basaltic Klipriviersberg Group, of which four out of six formations are present in the study area, namely, the Alberton, Orkney, Loraine and Edenville Formations. This group is succeeded unconformably by the PIatberg Group, consisting of the sedimentary Kameel doorns Formation, followed by the (informal) Goedgenoeg, Makwassie Quartz Porphyry and Rietgat Formations. The Goedgenoeg and Rietgat Formations are basaltic, whil e the Mawassie rocks range from basaltic to dacitic, the majority being tholeiitic andesites and andesites . The Pniel sequence at the top of the Ventersdorp Supergroup consists of the sedimentary Bothaville Formation, and the Allarridge Formation, the lavas of which are basaltic with some andesitic tendencies. A well-defined geochemical stratigraphy was found to exist. From the eleven volcanic formations examined, nine distinct geochemical units emerged, as the Loraine and Edenville Formations were found to have the same geochemical characteristics, as did the Goedgenoeg and Rietgat Formations. Despite having undergone law-grade greenschist facies metamorphism, very clear variation patterns with height are displayed by the immobile elements Ti, P, Kb, Zr and Y, and the light rare earth elements La, Ce and Nd. In contrast, much scatter was observed in the variation patterns of Na, K, Mn, Ba and Rb. Three techniques were employed to effect discrimination between formations - orthosonal discrimination, interelement and ratio vs ratio plots, and discriminant analysis. Confidence limits placed on normal probability plots served to isolate outlier samples for further examination by the various discrimination techniques. A successful test of the efficacy of the discrimination techniques was afforded when fourteen samples from an unknown succession were positively identified as representative of the Klipriviersberg Group
  • Full Text:
  • Date Issued: 1985

The geochemistry of basic volcanics of the Dordabis Formation northeast of Dordabis and their significance for correlations within, and evolution of, the Rehoboth Magmatic Arc

  • Authors: Marsh, Julian S , Williams-Jones, I E
  • Date: 1985
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/69763 , vital:29577 , http://www.mme.gov.na/files/publications/95f_Williams-Jones and Marsh_Dordabis Fm.pdf
  • Description: Gevers (1934) named the succession of quartzites, feld-spathic sandstones, massive conglomeratic arkoses and sedimentary breccias around Dordabis, the Dordabis Series. He considered this series to be of Nama age and the basic volcanics in the series to be post Nama, pre-Karoo eruptive diabase. Schalk (pers. comm.) has found the succession to be pre-Damara in age and possibly equivalent to the Sinclair Sequence. These ‘Dordabis Series’ rocks have since been incorrectly included into the Marienhof Formation of the Rehoboth Sequence on the 1980 1:1 000 000 Geological Map of SWA/Namibia. In this report, it is suggested that this succession be called the Dordabis Formation.
  • Full Text:
  • Date Issued: 1985

The geochemistry of potassic lavas from Vulsini, central Italy and implications for mantle enrichment processes beneath the Roman region

  • Authors: Rogers, N W , Hawkesworth, C J , Parker, R J , Marsh, Julian S
  • Date: 1985
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/136034 , vital:37330 , https://doi.org/10.1007/BF00378265
  • Description: Major and trace element and 143Nd/144Nd (0.51209–0.51216) and 87Sr/86Sr (0.70879–0.71105) isotope analyses are presented on a representative group of lavas from the Vulsini district of the Roman magmatic province. Three distinct series are identified; the high-K and low-K series are similar to those described from other Italian volcanoes, while the third is represented by a group of relatively undifferentiated leucite basanites which are thought to be near-primary mantle melts.
  • Full Text: false
  • Date Issued: 1985

The host-searching behaviour of coccophagus atratus compere (Aphalinidae: hymenoptera)

  • Authors: Clark, Maxwell Maitland
  • Date: 1985
  • Subjects: Coccophagus , Hymenoptera , Insects -- Host plants , Insect-plant relationships
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:5630 , http://hdl.handle.net/10962/d1004923 , Coccophagus , Hymenoptera , Insects -- Host plants , Insect-plant relationships
  • Description: The host-searching behaviour of the parasitoid Coccophagus atratus Compere was investigated. C. atratus parasitoids have unusual host relationships. Female offspring develop in scale insects but male offspring develop hyperparasitically on their conspecific females, or on other parasitoid species. C. atratus females, therefore, must locate, identify and oviposit into two different types of hosts. A primary aim of this thesis, was to identify when and how the behaviour of a female, searching for hosts suitable for female offspring, differed from that of a female searching for hosts suitable for male offspring. This was done by investigating and comparing the behaviour of virgin and mated females. Virgin females can lay only male eggs while mated females can lay both male and female eggs. The role of plant odours and host odours in attracting C. atratus females to the host habitat and to their scale insect hosts was examined with the aid of an olfactometer. Field observations, to test the validity of results obtained in laboratory experiments, indicated that C. atratus females do not search initially for for their hosts' food plants, but search directly for hosts. Only when hosts were physically located did the behaviour of virgin and mated females differ. Recognition cues used by the females to distinguish between the two types of hosts were identified. Finally, the implications of results obtained were discussed in relation to ecological and evolutionary aspects of heteronomous parasitoid biology.
  • Full Text:
  • Date Issued: 1985

The influence of ants on the insect fauna of broad-leaved, savanna trees

  • Authors: Grant, Susan
  • Date: 1985
  • Subjects: Ants -- Behavior , Insects -- Host plants
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:5811 , http://hdl.handle.net/10962/d1006971 , Ants -- Behavior , Insects -- Host plants
  • Description: The influence of foraging ants on the insect fauna within the canopy of the tree species Terminalia sericea, Burkea africana and Ochna pulchra was studied in an area of typical South African savanna, over a two year period. The number of individual insects and their species composition was compared on unbanded, ant-infested plants and on banded plants where ants had been excluded. Differences in the level of herbivory recorded on banded and unbanded trees were related to the guild composition of insects within the canopy, and the results are discussed in terms of plant protection as a consequence of ant - insect interactions. Twenty-six ant species were recorded on the study trees at Nylsvley, with individuals belonging to the genus Crematogaster being numerically abundant and dominant within the canopy of each species of tree. These dominant ant species influenced the insect fauna by their strong dependence on honeydew, encouraging a build up in numbers of Homoptera on the branches and leaves of foraged trees, and supporting homopterous populations within the confines of their nest compartments . The exclusion of ants from trees led to fewer "mobile" homopterans (Aphididae, Membracidae, Psyllidae and Cicadellidae) and "sessile" homopterans (mainly Coccidae but also Pseudococcidae). Pyrethrum spraying showed that the guild composition of non-homopterous insects was similar on banded and unbanded trees. Differences in the level of herbivory on banded and unbanded trees suggested that, although slight, foraged trees were protected from some damage by the presence of ant species within the canopy. A trend did exist towards a greater number of insect individuals and species on unbanded trees, and it is postulated that during the period 1982 1984 when drought conditions prevailed over Nylsvley, ants do not reduce insect numbers through predation or disturbance but simply deter phyllophagous feeding. A separate experiment showed that Crematogaster constructor would feed on the eggs and early instar larvae of the saturnid moth, Cirina forda, but low numbers of lepidopterous larvae on the trees may have forced ants to seek honeydew. The negative impact of large homopterous populations on foraged trees was only seen in an isolated field observation where Polyrachis schistacea was found to associate with the lac insect Tachardina sp . . In conclusion it can be said that where homopterans are not the dominant phyllophages, plants do benefit from foraging populations of ants in that damage to the leaves is reduced.
  • Full Text:
  • Date Issued: 1985

The life-world of youth in children's homes

  • Authors: Mudaly, Balasundran Subramani
  • Date: 1985
  • Subjects: Children -- Institutional care -- Psychological aspects Self in children Emotions in children Identity (Psychology) in children
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:2915 , http://hdl.handle.net/10962/d1002080
  • Description: The study sought to obtain an insightful understanding of the life-world of youth who have not only experienced long-term separation from their biological parents and families but who have also simultaneously experienced prolonged institutional life in a children'e home. Using a descriptive praxis in the context of an existential phenomenological perspective, the study elicited from participants written descriptions of their personal experiences of the phenomenon of self-fulfilment. The data were structurally analysed, expressed in the form of extended descriptions and utilised as the basis for an exposition/appreciation of the life-world relationships of institutional youth. The target group of teenagers was drawn from a specific children's home. However, in order to enhance the findings of the study, data from a comparative group of youth from intact families in the community were also utilised. The study yielded some useful comparative insights which not only formed the basis for certain recommendations but also served as directions for future research. Hopefully, these recommendations and research proposals will be of some immediate interest and comfort to both reeearchers and practitioners in the field of residential child and youth care
  • Full Text:
  • Date Issued: 1985

The mineralogy, petrology, and origin of the Merensky cyclic unit in the western Bushveld Complex

  • Authors: Kruger, Floris J , Marsh, Julian S
  • Date: 1985
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/136024 , vital:37329 , https://doi.org/10.2113/gsecongeo.80.4.958
  • Description: The Merensky cyclic unit of the Bushveld Complex represents the first products to crystallize after the influx and mixing of a large new batch of magma in the chamber. Excluding the Merensky pegmatoid, the Merensky cyclic unit grades upward from an orthopyroxenite at the base, through norite to anorthosite at the top of the sequence. It is followed by the very similar Bastard cyclic unit.
  • Full Text: false
  • Date Issued: 1985

The monitor and synchroniser concepts in the programming language CLANG

  • Authors: Chalmers, Alan Gordon
  • Date: 1985
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:4616 , http://hdl.handle.net/10962/d1006132
  • Full Text:
  • Date Issued: 1985

The petrogenesis of the volcanic rocks of the Witwatersrand triad in the Klerksdorp area, Transvaal

  • Authors: Bowen, Michael Peter
  • Date: 1985
  • Subjects: Volcanic rocks , Witwatersrand triad , Klerksdorp , Transvaal , Northwest Province , South Africa , Chemical analysis , Magma , Geology
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:4909 , http://hdl.handle.net/10962/d1001569
  • Description: Several hundred chemical analyses of early Proterozoic lavas of the Witwatersrand triad (incorporating the Dominion Group, Witwatersrand Supergroup and Ventersdorp Supergroup) in the Klerksdorp area, have revealed the presence of various distinct magma types. These essentially correspond to formally defined lithostratigraphic units, but several inconsistencies have necessitated the use of informal nomenclature. The lavas have been regionally metamorphosed to low-grade, greenschist facies assemblages. Original igneous textures are preserved, despite a metamorphic overprint. Metamorphism has resulted in a certain degree of random chemical remobilization. Ba, Sr, Rb, K₂0, Na₂0 and CaO have been highly mobile, and their usefulness in petrogenetic modelling is extremely limited. In contrast, Zr, Nb, Y, LREE's, Cr, Ni, Ti0₂ P₂0₅ and Al₂0₃ have remained immobile. Ti/Zr and Ti/P ratios together constitute efficient discriminating variables for characterizing the different magma types. Lava compositions range from primitive Mg-rich tholeiites to rhyolites, the bulk being tholeiitic andesites. Al₂0₃ contents do not exceed 15%, a feature which reflects the tholeiitic, as opposed to calcalkaline, character of these lavas. Two magma-types are present within the Dominion Group, which is a typical example of bimodal volcanism. The Dominion basic lavas are overlain by the Dominion acid porphyries, with a limited amount of interfingering. The basic lava suite is highly fractionated, with compositions ranging from Mg-, Cr- and Ni-rich tholeiites (close to primary mantle melts) to evolved tholeiitic andesites. The most primitive liquids evolved by 45% fractional crystallization of hornblende, followed by a further 70% crystallization of an orthopyroxene-plagioclase assemblage containing up to 3% sulphides. The Dominion porphyries are rhyolitic, display very limited compositional variation, and probably represent a crustal melt related to the same magmatic event which produced the basic lavas. The only lavas from the Witwatersrand Supergroup present in the Klerksdorp area are those of the Crown Formation (Jeppestown amygdaloid). These are tholeiitic dacites which display extremely limited compositional variation, and are unrelated to any of the other magmas of the Witwatersrand triad. The Ventersdorp Supergroup comprises 4 magma-types: The Kliprivierberg Group lavas at the base are subdivisible into 3 sub-types on the basis of Zr contents. (Zr>11Oppm) are the most evolved. They are tholeiitic andesites which display fairly limited compositional variation. It is likely that more evolved compositions are present in other areas where the porphyritic lavas which characterize this unit are better developed. The overlying Orkney lavas are characterized by 110ppm>Zr>90ppm. They are tholeiitic andesites of similar composition to the Alberton lavas, but have lower incompatible element levels, higher siderophile element levels, and are of extremely uniform composition. The uppermost Loraine/Edenville lavas range from magnesian tholeiites to tholeiitic andesites. They are distinguished by Zr< 90ppm, and contain the most primitive magmas af the Witwatersrand triad, with up to 17,5% MgO, 2600ppm Cr, 600ppm Ni and M-values up to 77. The most primitive liquids evolved by 38% fractional crystallization of orthopyroxene ∓ chromite, followed by 35% fractional crystallization of an extract containing clinopyroxene and plagioclase. The absence of olivine precipitation is a result of the inherently high Si0₂ content of the magma. The Loraine/Edenville, Orkney and Alberton lavas do not lie on a common liquid line of descent, but are probably consanguinous. The Platberg Group overlies the Kliprivierberg Group, and has a coarse-clastic sedimentary unit, the Kameeldoorns Formation, at the base. Three petrographically distinct porphyritic lava sequences overlie the Kameeldoorns Formation, namely the informal "Goedgenoeg formation", the Makwassie quartz-feldspar porphyries and the Rietgat Formation. Despite petrographic differences, the Goedgenoeg and Rietgat lavas are chemically indistinguishable and thus form a single magma-type. The Makwassie porphyries are dacitic in composition with a high proportion of feldspar and quartz phenocrysts. Rational variation trends are attributed to a nett loss of Si0₂ during secondary alteration. The porphyries are probably of crustal origin. The Goedgenoeg/Rietgat lavas display unusual chemistry and a broad, irrational compositional spectrum. They contain very high incompatible element levels, high nonnative quartz, as well as high MgO, M-values, Cr and Ni relative to the other tholeiitic andesites of the Witwatersrand triad. It is tentatively suggested that they are hybrid magmas containing both crust and mantle components, the former possibly represented by the Makwassie porphyries. Field evidence suggests that Platberg volcanism commenced directly after Klipriviersberg volcanism ceased, and was accompanied by a period of enhanced tectonic activity. The Platberg lavas thus probably reflect a crustal melting cycle associated with the Klipriviersberg magmatic event. The Allanridge lavas are the youngest rocks of the Witwatersrand triad. They are separated from the Platberg Group by a unit of flat-lying sediments, the Bothaville Formation, which was deposited after an extended period of peneplanation. The Allanridge lavas form a separate magma-type. They are tholeiitic andesites of similar composition to the Alberton lavas, but have higher incompatible element levels and are not consanguinous. The compositional similarities amongst the basic magma-types of the Witwatersrand triad suggests that all were generated in an hydrous mantle. Interelement ratio differences between the various magma-types nevertheless support the concept that the mantle was chemically heterogeneous during the early Proterozoic.
  • Full Text:
  • Date Issued: 1985

The petrology of the basalts of the Dordabis Formation in the vicinity of Dordabis in central S.W.A./Namibia|

  • Authors: Williams-Jones, Ian Eric
  • Date: 1985 , 2013-03-14
  • Subjects: Basalt -- Namibia , Petrology -- Namibia , Geochemistry -- Namibia
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:5062 , http://hdl.handle.net/10962/d1013277
  • Description: The late Proterozoic volcanic and sedimentary sequence in the Dordabis area SWA/Namibia has been named the Dordabis Formation and subdivided, on the basis of field, petrological and petrographic evidence, into the Opdam and Bitterwater Members. Relict phases including augite and minor plagioclase only occur in the Bitterwater metalavas, as recrystallisation is complete in the Opdam metal avas. The composition of the relict feldspars ranges from labradorite in the ophitic basalts to oligoclase in the blastoporphyritic metalavas. The feldspars in the Opdam member are albitic in composition (An content 0,0 to 1,7) . Epidote compositions are typical of those occurring in metabasic rocks. Samples with high-iron whole-rock compositions are accompanied by high concentrations of Fe3+ in concomitant epidotes. Sixty three samples were analysed using X-ray fluorescence spectrometry to determine concentrations of major and 16 trace elements. Although greenschist facies metamorphism, metasomatism and shearing have produced scatter in the more mobile element concentrations, variation trends in other elements closely resemble modelled low-pressure fractional crystallisation trends. The Dordabis metalavas are petrologically classified as sub-alkaline, tholeiitic continental basalts. Low K/Rb ratios and low ratios of less incompatible to more incompatible elements probably reflect a source that has either been metasomati ca lly enriched or that has undergone little previous partial melting. Overlapping whole-rock variation trends indicate that the generally more evolved Opdam and primitive tholeiitic Bittenwater lavas are cogenetic. A comparison of the Dordabis Formation with the Sinclair Sequence and the Koras Group shows that their ages, petrology, petrography, associ a ted sedimentary suites and depositional environments are similar. It is concluded that they may possibly be coeval equivalents.
  • Full Text:
  • Date Issued: 1985

The place of classical civilization in the school curriculum

  • Authors: Morton, Anne Caroline
  • Date: 1985
  • Subjects: Education -- Curricula -- South Africa Civilization, Classical -- Study and teaching Latin language -- History -- 20th century Latin language -- Study and teaching (Secondary) -- South Africa
  • Language: English
  • Type: Thesis , Masters , MEd
  • Identifier: vital:1378 , http://hdl.handle.net/10962/d1001444
  • Description: Classical Studies, as a subject, has not been seriously presented in many schools until fairly recently. Britain initiated the introduction of Classical Studies to the school curriculum in 1974, and interest has continued to grow steadily in other countries like America, New Zealand, Australia and Canada. This thesis was started on the assumption that this entirely new subject could be introduced into the curriculum for standard six and seven pupils at South African schools, for reasons which will be given later. As work continued on the thesis, the 1985 syllabus for Latin lent it further impetus. Some of the implications of the new Latin syllabus will be considered in the conclusion (Introduction, p. 6)
  • Full Text:
  • Date Issued: 1985

The playing characteristics of American trombones and German-system bassoons

  • Authors: Galloway, David John
  • Date: 1985
  • Subjects: Trombone Bassoon
  • Language: English
  • Type: Thesis , Masters , MMus
  • Identifier: vital:2661 , http://hdl.handle.net/10962/d1004508
  • Description: Preface: South Africa, a country renowned for its mineral wealth has, perhaps manufacturing paradoxically, no musical wind instrument industry of its own as yet. Thus performers, educators and students alike have either to travel to Europe or America to select an instrument, or to import an expensive instrument that may be both unseen and untried, as very few musical instrument dealers are prepared to outlay capital on stock which appeals to a decided minority of their potential customers. Alternately, a purchase of a particular make or model can be made on the basis of a hearsay opinion; at best, the opportunity for first-hand assessment is minimal. It is the trombone of U. S.A. manufacture and the German bassoon which represent the current state of their respective manufacturing arts, and the yardsticks by which their many imitator's efforts are measured. One of the main aims of this Thesis is to describe in objective terms what has been experienced subjectively over the years of involvement with these instruments -- arguably a task similar to that of the art critic, but operating within more positively defined parameters namely, what works for the student and professional. , and what doesn't. The candidate claims credit for introducing the large-bore Bb/F trombone to South Africa in 1961, following with the introduction of the ·first double-valve bass trombone in 1965, and the first in 1979. The first Schreiber bassoons The advantages and trombone and other bassoon and other such instrument with in-line rotors of the new 5000 series larger-bore was likewise introduced in 1981. pitfalls of " doubling" between the wind instruments , and between the winds, are disc ussed at length in the final section of the Thesis.
  • Full Text:
  • Date Issued: 1985

The plea of truth and public benefit as a defence to an action for defamation in South African law

  • Authors: Grogan, John
  • Date: 1985
  • Subjects: Libel and slander -- South Africa
  • Language: English
  • Type: Thesis , Masters , LLM
  • Identifier: vital:3708 , http://hdl.handle.net/10962/d1006974
  • Description: From introduction: The study begins with a detailed examination of the origins of the defence in Roman law, and traces the dispute over the role of the veritas convicii through the writings of the Roman-Dutch jurists and the decisions of the pre-Union colonial courts in South Africa. The gradual absorption of the requirement of public benefit into the contemporary law is examined. Subsequent sections attempt to extract from the case law and to systematise the rules relating to the requirements of the defence of truth and public benefit, with a view to setting forth the circumstances in which the truth may lawfully be published. Section 2 deals with problems relating to proof of the truth of the imputation; Section 3 with the problem of when publication can be said to serve the public benefit. The final section seeks to examine the juridical basis of the defence and to relate it to recent developments in the law of defamation as a whole. Brief conclusions are then drawn and recommendations made.
  • Full Text:
  • Date Issued: 1985

The relationship between the concept 'art' and its institutionalisation during the period 1850-1871 in South Africa

  • Authors: Steyn, Pieter Andrew
  • Date: 1985
  • Subjects: Art, South African -- 19th century Art -- Political aspects Art and society -- South Africa
  • Language: English
  • Type: Thesis , Masters , MFA
  • Identifier: vital:2438 , http://hdl.handle.net/10962/d1005626
  • Description: This research evolved as part of a personal struggle to understand my role as 'art' student. As such the essay is concerned with both the theory and practice of 'art', and the relationship between the two. It is, however, my experience of the lack of an analysis of the concept 'art' as a social and historical phenomenon, and the suppression of the politics of culture in most fine art courses, that has led me to concentrate on theoretical and political issues, rather than the formal aspects of painting. This essay is therefore not concerned with individual 'works of art', but with the general category 'art' as an organisational form. Despite its limitations, the essay goes beyond the personal by exploring some of the social, political, economic and cultural processes that form the broader social context in which the examination of 'art' should take place.
  • Full Text:
  • Date Issued: 1985

Thina Singabantwana base St Bede

  • Disclaimer
  • Privacy
  • Copyright
  • Contact