No CrossRef data available.
We use cookies to distinguish you from other users and to provide you with a better experience on our websites. Close this message to accept cookies or find out how to manage your cookie settings.
We use cookies to distinguish you from other users and to provide you with a better experience on our websites. Close this message to accept cookies or find out how to manage your cookie settings.
Published online by Cambridge University Press: 01 May 2009
It may be taken for granted that everybody agrees with Dr. Molengraaff when, in discussing Dr. Hatch's paper on “The Oldest Sedimentary Rocks of the Transvaal,” he says: “There must exist, or have existed, a formation older than the Witwatersrand Beds, because even at the very base of the Hospital Hill series conglomerates are known, the pebbles of which cannot obviously have been derived from the Hospital Hill series by denudation.” It has, therefore, I take it, not been the intention of various authors to prove this self-evident truth, but only to try and definitely settle the still open question whether this older rock is yet represented in the geological sequence of the country, and, if so, what strata should be identified as such. The relative age of the ‘old granite’ or ‘grey granite’ has been the base and the cornerstone of controversy on this subject, and it therefore becomes imperative to put on record and to continually keep in mind the only reliable mode of determination of the age of eruptive rocks which we yet possess. It would be out of place here to insist upon the origin of abyssal eruptive rocks of the granite family (Rosenbusch's Tiefengesteine).
page 552 note 1 Woodward, , Geol. Mag., 1870, 12 I, Vol.VII, p. 556, PI. XXIII, Figs. 6, 6a.Google Scholar
page 552 note 2 Ibid., p. 555, PI. XXIII, Figs. 5, 5a.
page 552 note 3 Ibid., p. 554, PI. XXIII, Figs. 3, 3a.
page 552 note 4 Ibid., 1893, Dec. III, Vol. X, p. 28, woodcuts A and B; 1894, Dec. IV, Vol. I, p. 536.
page 552 note 5 Ibid., 1870, Dec. I, Vol. VII, p. 557, Text-figures 1, 2 on p. 558; 1894, Dec. IV, Vol. I, p. 535, Pl. XV, Figs. 1a, 1b.
page 552 note 6 Molengraaff, G. A. F.: Proc. Geol. Soc. S. Africa, to accompany vol. vii of the Transactions, p. xxix.Google Scholar
page 554 note 1 Sehenck, A., “Die Geologische Entwickelung Süd-Africas”: Petermanns Mitteil., 1888, Bd. xxxiv, pp. 225–32.Google Scholar
page 554 note 2 For Witwatersrand Beds we shall henceforth simply write W. W. R. Beds.
page 554 note 3 Molengraaff, G. A. F.: “Geologische Aufnahme der Süd-Afrikanische Republik” (79 + xvii pp. in 4to, Pretoria, 1898), pp. 10, 27, and 35–8.Google Scholar
page 554 note 4 Dorffel, D., “Note on the Geological Position of the Basement Granite”: Trans. Geol. Soc. S. Africa, 1903, vol. vi, pt. v, pp. 104, 105.Google Scholar
page 554 note 5 Corstorphine, G. S., “The Geological Relation of the Old Granite to the Witwatersrand Series”: Trans. Geol. Soc. S. Africa, vol. ii, pt. i, pp. 9–12.Google Scholar
page 555 note 1 Sandberg, C. G. S.: “Etudes géologiques sur le Massif de la Pierre-à-voir (Bas Valais),” 129 pages in 8vo, Paris, 1905, pp. 108–10Google Scholar; “Ĺâge du granit des Alpes occidentales et ľorigine des blocs exotiques cristallins des Klippes,” C. R. Ac. Sc, 1905, t. cxl, pp. 1072, 1073 (10 avr.); “Ĺâge du granite Alpin,” Arch. Sc. phys. nat. (4), Genève, 1907, t. xxiii, pp. 581–94. Weinschenk, E., “Grundzüge der Gesteinskunde,” 2 vols., Freib.-i.-Breisgau, 1906.Google Scholar
page 555 note 2 Molengraaff, G. A. F., discussion on Mr. Jorissen's paper, “Note on some Intrusive Granites, etc.,” Proc. Geol. Soc. S. Africa, to accompany vol. vii, p. xxxii.Google Scholar
page 555 note 3 DrMolengraaff, G. A. F.: Discussion of above paper, Proc. Geol. Soc. S. Africa, to accompany vol. vii, pp. xxix–xxxi.Google Scholar
page 555 note 4 DrHatch, F. H., “The Oldest Sedimentary Eocks of the Transvaal”: Trans. Geol. Soc. S. Africa, vol. vii, pt. iii, pp. 147–50.Google Scholar
page 556 note 1 Jorissen, E., “Notes on some Intrusive Granites in the Transvaal, the Orange River Colony, and in Swaziland”: Trans. Geol. Soc. S. Africa, 1905, vol. vii, pt. iii, pp. 151–60Google Scholar; and discussion of Dr. Molengraaff, G. A. F. on the above, Proc. Geol. Soc. S. Africa, to accompany vol. vii, pp. xxxi–xxxiii.Google Scholar
page 556 note 2 Jorissen, E., loc. cit., p. 156.Google Scholar
page 556 note 3 Loc. cit., p. 154.
page 556 note 4 As a matter of fact, it is just possible that these schists, far from being Archæan, will prove to be nothing less than metamorphosed Pretoria series.
page 557 note 1 Hall, A. L. & Humphrey, W. A., “The Blackreef Series and the underlying formation in the neighbourhood of Kromdrasi and Zwartkop, north of Krugersdorp”: Trans. Geol. Soc. S. Africa, 1906, vol. ix, pp. 10–15.Google Scholar
page 557 note 2 Sandberg, C., “Notes on the Structural Geology of South Africa”:. Trans. Inst. Min. Eng., vol. xxxii, pt. v, pp. 540–57.Google Scholar
page 559 note 1 On Dr. Hatch's geological map of the Southern Transvaal the phenomenon of the above-mentioned granite fenêtres is clearly expressed (Koedoeslaagte, No. 59).
page 559 note 2 See also Sawyer, A. R., “New Rand Gold Fields, Orange River Colony”: Trans. Inst. Min. Eng., vol. xxxiii, pt. v, pp. 530–4.Google Scholar
page 559 note 3 Weinschenk, E.: “Grundzüge der Gesteinskunde” i, pp. 168, 169Google Scholar. Since the assimilation of the Johannesburg-Vredefort-Klerksdorp ‘old granite’ with the Zoutpansberg-Swaziland-Rhodesia rock is exclusively based on lithological grounds only and must therefore be considered as inadequate, I have purposely. although personally inclined to regard these igneous rocks as identical, not included them directly in the summary of my argument.
page 559 note 4 Hall, A. L. & Humphrey, W. A., loc. cit., p. 11, pl.iii.Google Scholar