466 C. B. Horn-ood Sf A. Wade—The Old Granitos of Africa. 



produced a large flexure or anticline, and was not therefore posterior 

 to the uplifted rocks". Then in the same paper he says, " since then 

 I have found out by boring that the dip of the Witwatersrand and 

 Hospital Hill Beds is steeper near the granite," and he suggests that 

 the steep dip of the rocks east and west of the granite points to the 

 granite being intrusive in them. 



Thus, in his opinion, the Old Granite is the basement rock on which 

 the Witwatersrand Beds were laid down, and which subsequently 

 invaded them by after-intrusions. It is also of interest to note that in 

 1897 ^ he mentioned an occurrence of granite containing veins of white 

 quartz on the farms Varkenskraal and Klerkskraal, which are traversed 

 by the Mooi River, 35 miles north of Potchefstroom, and stated that 

 banket reefs (Black Keef Series) containing glassy white quartz 

 pebbles can be seen resting on the granite on these farms, and that 

 the white quartz veins of the granite "can be seen passing through 

 various gradations of decomposition until they reach the final stage 

 of banket pebbles". 



Dr. Molengraaff, in his report for the year 1897, as State Geologist 

 of the South African Republic, under the term South African Primary 

 Formation with Intrusive Granite Bosses, includes — 



1. Granite and schists. 



2. Hospital Hill Series and Barberton Beds. 



3. Witwatersrand Series. 



And he states that the beds of this formation have been much altered, 

 both by dynamo-metamorphism and by contact- metamorphism, in 

 the vicinity of the granite bosses. Also, he speaks of numerous 

 granite masses which are found intrusive in this formation. Later, 

 in the same report, he speaks of the granite as intrusive in the 

 bottom part of this formation. 



In his report for the following year he classes the Witwatersrand 

 Series (our present Witwatersrand Beds) as the upper division of 

 the Barberton Series, and in his table of the sequence of the various 

 formations he puts the Barberton Series as conformable with the 

 Old Granite and schists, but puts a query mark against the sign 

 for conformability. 



In a paper" read by him in June, 1903, on the tectonics of the 

 Yredefort district he shows in a most convincing manner how the 

 overtilting of the beds is there due to the intrusion of the granite. 

 The chief arguments which he brings forward in support of this 

 contention are that at a certain distance from the great central granite 

 boss small enclosures of granite are found entirely surrounded by 

 rocks of the South African Primary System, being apparently 

 offshoots of the main granite boss ; also that unmistakable signs of 

 strong contact-metamorphism are found in the lowest portion of the 

 sedimentary strata around the granite, the strata nearest to granite 

 being entirely crystalline, and having the character of crystalline 

 schists, especially actinolite schist; and up to some distance from 



' Loc. cit., p. 13. 



2 "Remarks on the Vredef ort Mountain-Land," by G. A. F. MolengraafE: Trans. 

 Geol. See. S.A., vol. vi, pt. ii, pp. 20-6. 



