556 Dr. C. Sandherg—The * Old Granite ' of the Transvaal. 



Mare (Pietersburg), which, notwithstanding their altered state through 

 contact - raetamorphisra, still surprisingly resembles, by his own 

 admission, the Lower W.W.R. Beds. He cannot, either here or in 

 the Barberton-Swaziland area, mention one single localitj' where to 

 his own satisfaction undoubted W.W.E.. Beds are found together 

 with these highly metamorphosed rocks, and where they occur in 

 a mutually unconformable relation. Everywhere the covering (if 

 any) of these crystalline schists consists of strata considerably 

 younger than even the Upper W.W.R. Beds. Still, he does not 

 accept the probability of being in the presence of metamorphosed 

 "W.W.E.. Beds, but jumps to the conclusion that these metamorphic 

 rocks, so similar to the W.W.E.. Beds, must be much older and 

 belong to the Archaean system, simply because the ' old or grey 

 granite ' is supposed to be intrusive in these schists, and is ' proved ' 

 to be non-intrusive in the W.W.R. Beds ! 



Mr. Jorissen's reasoning by which he arrives at the same conclusion is 

 stranger still, if possible.' He describes some eight different localities 

 distributed over the whole of the Transvaal where he discovered the 

 ' Archaean formation.' Like Dr. Hatch, he evidently cannot mention 

 one single instance where he found AV.W.B. Beds and the so-called 

 older (Archaean) rock together. Like Dr. Corstorphine, he is satisfied 

 that the sericite-schist separating the Orange Grove quartzites (and 

 evidently conformable therewith, since he also does not mention the 

 all-important fact of their being unconformable) from the granite on 

 the farm Vergenoeg, No. 220,- is a segregation from the granite, and not 

 due to the metamorphic action on quartzites of the yet unconsolidated 

 granite (see above, p. 554). Further, on the farm Nooitgedacht, No. 565 

 (Pretoria District), Joi'issen describes a patch of crystalline schists 

 which he discovered in the ' old granite,' and by which it is trans- 

 formed through contact-metamorphism.^ This ' old granite ' now 

 occurs as a welcome oasis in the surrounding endless desert of typical 

 new or red or Bushfeld granite right in the classical region from 

 which the new granite derives its name, in the Bushfeld. It is clear 

 that the only reason why Jorissen could assimilate the granite patch 

 there with the ' old granite ' is the presence of * Archiean schists ' 

 evidently metamorphosed by it, whilst the only reason for concluding 

 that he was in the presence of ' Archaean schists ' here, must have 

 been the fact of these schists having been transformed by contact- 

 metamorphism with the ' old granite ' ! * On the farm Malipskraal, 

 No. 406 (Lydenburg), he describes some more ' Archaean rocks ' which, 

 according to Mr. Kynaston, are most likely a foliated norite belonging 

 to the Biishveld Series. 



Finally, Mr. Hall & Dr. Humphrey, of the Geological Survey of 

 the Transvaal, accepting this topsy-turvy reasoning, assign certain 



' E. Jorissen, "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. 1.51-60 ; and discussion of Dr. G. A. F. Molengraaff on the above, Proc. 

 Geol. Soc. S. Africa, to accompany vol. vii, pp. xxxi-xxxiii. 



- E. Jorissen, loc. cit., p. 156. 



^ Loc. cit., p. 154. 



* As a matter of fact, it is just possible that these schists, far from being Archaean, 

 will prove to be nothing less than metamorphosed Pretoria series. 



