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V.—Contributions to South African Petrography

Published online by Cambridge University Press:  01 May 2009

F. P. Mennell
F. P. Mennell
Affiliation:
Curator of the Rhodesia Museum, Bulawayo.
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Extract

It is remarkable, considering the enormous development of igneous rocks in South Africa, that so little has been written concerning the features they present in the field or under the microscope. Right away from Cape Town into the tropics, plutonic masses, dykes, and lava-flows interrupt the continuity of the sedimentary deposits with astonishing frequency. Some of these rocks, like the Cape Town granite and dolerite, are probably of pre-Silurian age; others, like the Kimberley lavas, were erupted during the Secondary period: while others, again, like the dykes and lavas of the Zambesi Valley, are probably of late Tertiary or even geologically recent date, as evidenced by the numerous geysers and hot springs which represent the final phase of not long antecedent volcanic activity. They appear to bear the same relation to the volcanoes of Central Africa as the British Tertiary lavas do to those of Iceland.

Type
Original Articles
Information
Geological Magazine , Volume 9 , Issue 8 , August 1902 , pp. 356 - 366
Copyright
Copyright © Cambridge University Press 1902

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References

page 356 note 1 They are overlain unconformably by a thick formation which is itself older than the earliest fossiliferous beds (Devouian) of South Africa.

page 356 note 2 See Ferguson on the geysers of the Zambasi and Kaful Valleys. Proc. Rhodesia Sci. Assoc., 1902.Google Scholar

page 357 note 1 This is obviously a different rock to that described by Stelzner.

page 359 note 1 This is no doubt the rock referred to by ProfessorBonney, , Geol. Mag., 1897, p. 449.Google Scholar

page 362 note 1 Cohen, : N.J. für Min., 1874Google Scholar. See also Shaw, : Proc. S.A. Phil. Soc., vol. i, pt. 2 (1879), p. 59.Google Scholar

page 363 note 1 N.J. für Min., 1874.Google Scholar

page 364 note 1 See MacMahon on the gneissose-granite of the Himalayas, Geol. Mag., 1897, pp. 345–355.Google Scholar

page 364 note 2 “The Copper-bearing Rocks of South Australia”: Brit. Assoc., 1901.Google Scholar

page 366 note 1 T.M.M., 1894, p. 188Google Scholar. See also Ann. Rep. Cape Geol. Comm., 1898.Google Scholar