498 C. B. Rorwood 8f A. Wade— The Old Granites of Africa. 



maintained that the Old Grranite is not intrusive in the Witwatersrand 

 System ; but that the latter was laid down on the granite. 



Again, in December of the same year, Mr. E. Jorissen ^ described 

 occurrences in the Central, Western, and Northern Transvaal, and 

 just over the eastern border in Swaziland; and also in the Yredefort 

 district of the Orange River Colony, where he maintained the Old 

 Granite is intrusive into either schists or quartzites, as the case may 

 be, older than the Witwatersrand System. He suggested that these 

 quartzites and crystalline schists must be considered as the remnants 

 of an Archaean formation in the Transvaal, the existence of which 

 Mr. Dorffel had already assumed. 



Simultaneously with Mr. Jorissen's paper another appeared by 

 Dr. !F. H. Hatch,'^ in which he pointed to the existence of sedimentary 

 rocks, composing the hill range of Mount Marais, near Marasbastad, 

 8 miles south of Pietersburg, which have suffered great contact- 

 metamorphism from the presence of the Old Granite, which has been 

 intruded into them. He argued that these sediments are therefore 

 older than the Witwatersrand System, since the latter was shown by 

 Dr. Corstorphine to rest unconformably on the Old Granite. The 

 author stated that his investigation of the Mount Marais rocks and 

 a comparison of them with those of Barberton had led him to the 

 conviction that these beds, for which he proposed the name of 

 Swaziland Series,^ are well represented in the Transvaal by the 

 great series of schists comprising the rolling uplands of Swaziland, 

 by the Moodies and Sheba Ranges at Barberton, and by the hill 

 country near Marabastad. He also pointed out* that the pebbles of 

 which the conglomerates of the Witwatersrand System are composed 

 are derived from just such rocks as occur in this Swaziland Series. 



Mr. H. Kynaston, Director of the Transvaal Geological Survey, in 

 discussing these last two papers,^ said he had a few months ago 

 paid a flying visit to the rocks of Mount Marais ; and went on to 

 say that " the two papers had certainly conclusively proved that the 

 Older Granite was intrusive in an older series of altered sedimentary 

 rocks. One of the chief arguments of the author against the Mount 

 Marais rocks being of Lower Witwatersrand age was that the Older 

 Granite was not intrusive in these latter beds. This fact he did not 

 feel quite satisfied in his mind as having been as yet conclusively 

 proved, and further, there was always the possibility of separate 

 masses of the Older Granite belonging to slightly different periods of 

 intrusion. A short visit last year to the Venterskroon district had 

 left the decided impression in his mind that the Vredefort granite 

 was intrusive in the surrounding strata of Lower Witwatersrand age, 

 and he had particularly noticed the corundum bearing and other 



^ " Notes on some Intrusive Granites in the Transvaal, the Orange River Colony, 

 and in Swaziland," by E. Jorissen: Trans. Geol. Soc. S.A., vol. vii, pt. iii, 

 pp. 151-60. 



• " The Oldest Sedimentary Rocks of the Transvaal," by F. H. Hatch: Trans. 

 Geol. Soc. S.A. , vol. vii, pt. iii, pp. 147-50. 



^ This name has since been generally adopted. 



•* Loc. cit., p. 148. 



^ Proc. Geol. Soc. S.A., 1904, to accompany vol. vii of the Transactions, p. 62. 



