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III.—The Geological History of South Africa1

Published online by Cambridge University Press:  01 May 2009

F. H. Hatch
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Extract

After the granites, gneisses, schists, and sediments which make up the Swaziland System had been elevated to form a continental area extending over the northern and western portions of South Africa, denudation began, and the material thus produced was carried to the sea to form the Witwatersrand Beds. The nature of these sediments—they consist of conglomerates, grits, and shales—indicates a marine period with shallow-water conditions, which continued almost uninterruptedly during their deposition. They were accumulated first on a sinking, and then on a rising sea bottom, for the lower beds are composed largely of mud and fine sand, conglomerates only becoming abundant in the upper beds, which were formed in the later portion of the period when the sea had become sufficiently shallow to allow of the accumulation of shingle and gravel. There is evidence in the Southern Transvaal that the land from which the sediments were mainly derived lay to the west, the sea to the east, for the lower Witwatersrand Beds, which consist solely of mudstones and fine sandstones in the east, gradually develop conglomerates with a decreasing amount of shale towards the west.

Type
Original Articles
Information
Geological Magazine , Volume 3 , Issue 4 , April 1906 , pp. 161 - 168
Copyright
Copyright © Cambridge University Press 1906

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Footnotes

1

Presidential Address delivered by Dr. F. H. Hatch to the Geological Society of South Africa, 29th January, 1906.

References

page 162 note 1 Molyneux, A. J. C.: Q.J.G.S., vol. lix (1903), p. 283.Google Scholar

page 162 note 2 F. H. Hatch, “The Extension of the Witwatersrand Beds eastward under the Dolomite,” etc.: loc. cit., p. 68.

page 163 note 1 Holmes, G. G., “Some Notes on the Geology of the Northern Transvaal”: Trans. Geol. Soc. S. Afr., vol. vii (1904), pp. 55–56.Google Scholar “The Geology of a part of the Rustenburg District”: Trans. Geol. Soc. S. Afr., vol. viii (1905), p. 6.Google Scholar

page 163 note 2 Mellor, E. T., “Volcanic Action in the Waterberg Formation”: Trans. Geol. Soc. S. Afr., vol. iii (1905), p. 38.Google Scholar

page 163 note 3 Mellor, E. T.: Transvaal Geol. Surv. Rep., 1903, p. 17.Google Scholar

page 164 note 1 Mellor, E. T., “The Waterberg Sandstone Formation”: Trans. Geol. Soc. S. Afr., vol. vii (1904), p. 40.Google Scholar Mr. Mellor instances the occurrence of boulders ranging up to 8 feet in diameter. These must have been transported by streams of a torrential character.

page 164 note 2 Rogers, A. W., “The Glacial Conglomerate in the Table Mountain Series near Clanwilliam”: Trans. S. Afr. Phil. Soc., vol. xvi (1905), p. 1.Google Scholar

page 164 note 3 Rogers, A. W.: “The Geology of South Africa,” p. 395.Google Scholar

page 164 note 4 “Geology of the Cape Colony,” p. 396.

page 165 note 1 Mellor, E. T.: Transvaal Geol. Surv. Rep., 1903, p. 20.Google Scholar

page 165 note 2 Dunn, E. J., “Notes on the Dwyka Coal-measures”: Trans. S. Afr. Phil. Soc., vol. xi (1900), p. 67.CrossRefGoogle Scholar

page 165 note 3 David, Edgeworth, “Evidences of Glacial Action in Australia in Permo-Carboniferous Time”: Q.J G.S., vol. lii (1896), p. 289.CrossRefGoogle Scholar

page 166 note 1 Seward, A. C.: Q.J.G.S., 1897, p. 322.Google Scholar

page 166 note 2 An interesting account of the geological history of these eruptions is given by Toit, Mr. du in a paper on “The Forming of the Drakensberg”: Trans. S. Afr. Phil. Soc., vol. xvi, pt. 1 (1905), p. 65.Google Scholar See also “Report on part of the Matatiele-Division, with an Account of the Petrography of the Volcanic Rocks,” by Schwarz, E. H. L.: Geol. Comm. Rep. for 1902, p. 11; Capetown, 1903.Google Scholar Also “Geological Survey of Elliott and Xalanga,” by Toit, A. L. du: Geol. Comm. Rep. for 1903, p. 109; Cape Town, 1904.Google Scholar

page 166 note 3 Mellor, E. T.: Transvaal Geol. Surv. Rep., 1904, p. 31; Pretoria, 1905.Google Scholar Also Trans. Geol. Soc. S. Afr., vol. viii (1905), p. 37.

page 167 note 1 Rogers, & Schwarz, : Ann. Rep. Geol. Comm., 1901, pp. 25–46; Capetown, 1902.Google Scholar

page 167 note 2 Toit, A. C. du, “The Forming of the Drakensberg”: Trans. S. Afr. Phil. Soc., vol. xvi (1905), p. 67.Google Scholar

page 167 note 3 Rogers, & Toit, Du, “The Sutherland Volcanic Pipes and their Relationship to other Vents in South Africa”: Trans. S. Afr. Phil. Soc., vol. xv (1901), p. 61.Google Scholar

page 168 note 1 “Das Antlitz der Erde,” vol. i, p. 768; Vienna, 1885.Google Scholar

page 168 note 2 Blanford, W. T.: Presidential Address, Proc. Geol. Soc., vol. xlvi (1890), p. 106.Google Scholar