554 Dr. C. Sandberg—The ' Old Granite' of the Transvaal 



result of Dr. G. S. Corstorphinc's conclusions, dispute with each other 

 the title of being its strongest advocate. 



Dr. A. Schenck,' in 1888, tlrst made a distinction between the 

 Witwatersrand Beds - and the Swazi Beds, placing the latter 

 at the bottom of the sedimentary series, evidently exclusively 

 because of the then prevalent ideas which assigned all gneiss and 

 crystalline schists, as a matter of course, to the Archaean system. 

 Dr. G. A. F. MolengraalS,^ who was naturally impressed by the great 

 similarity both in the composition of the individual members and in 

 the succession of the component strata of the Barberton (Swazi) and 

 W.W.R. Beds,^ who was struck by the perfect conformability between 

 the Barberton Schists and the enclosed conglomerate formation so 

 identical with the W.W.E.. Beds,^ who lastly found both uncon- 

 formably covered by much younger and identical formations, naturally 

 placed them in the same system and on the same geological horizon 

 at the base of our geological sequence. His ruling was for some time 

 generally accepted, until in 1903 Mr. Dorffel ^ reopened the question 

 with a paper, the essence of which is contained in his final remarks — 

 "At present I am not of opinion that the old granite is intrusive in 

 the Witwatersrand Beds. . . . If the old granite be not mtrusive 

 in the W. W.R. Beds, ice have to assume the existe7ice of an Archaan 

 formation.'''' (The italics are mine.) Dr. G. S. Corstorphine, taking 

 up this line of argument, soon afterwards concludes as to the non- 

 intrusiveuess of the old granite in the "W.W.lt. Beds, and to the 

 ' consequent ' existence of an Archasan formation, on the following 

 grounds: — ' 



"On one farm (east of Heidelberg, TJitkyk No. 97) Dr. Corstorphine 

 finds the actual contact of the ' old granite ' and the Lower W.W.R. 

 Beds along an exposure of 200 yards. He cannot discover any intrusion 

 of granite in the quartzites, nor any contact-phenomena between the 

 two rocks. He furthermore cannot find any granite pebbles in the 

 superposed quartzites. Rounded, water-worn boulders of white and 

 bluish vein-quartz, which he is convinced originated from the breaking 

 up of some of the numerous veins in the granite, are, however, 

 conspicuous in these lower quartzites. He is impressed by the granite 

 imder the quartzites here showing a rounded and worn surface, and 

 finally declares that he has not been able in any of the localities 

 which he had the opportunity of examining elsewhere to recognise 

 a series of schists forming the lowest portion of the W.W.B. series. 

 What have been taken for schists and even for quartzites in several 

 localities are really, according to Dr. Corstorphine, differentiations 

 and variations in the granite itself." 



It must at once strike the mind of the reader that Dr. Corstorphine 



' A. Scheuck, "Die Geologische Entvvickeluug Sud-Afiicas " : Petermanns 

 Mitteil., 1888, Bd. xxxiv, pp. 225-32. 



* For Witwatersrand Beds we shall henceforth simply write W.W.R. Beds. 



^ G. A. F. Molengraaff : "Geologische Avifuahme der Siid-Afrikanische 

 llepublik" (79 + xvii pp. in 4to, Pretoria, 1898), pp. 10, 27, and 35-8. 



* D. Dorffel, " Note on the Geological Position of the Basement Granite " : Trans. 

 Geol. Sec. S. Africa, 1903, vol. vi, pt. v, pp. 104, 105. 



* G. S. Corstorphine, "The Geological Kelation of the Old Granite to the 

 Witwatersrand Series" : Trans. Geol. Soc. S. Africa, vol. vii, pt. i, pp. 9-12. 



