PRE-CAPE ROCKS OF THE NORTH OF THE COLONY 79 



three members of the Transvaal system. The three 

 groups are found over some 23,000 square miles east of 

 the Langberg-Korannaberg Range. 



They have not been definitely recognised west of this 

 range nor in the south of the Colony, in spite of the 

 assumption often made that the dolomitic rocks of the 

 Cango series., must belong to the same group as those of 

 the Campbell Band series. 



Though a few travellers, such as Lichtenstein and 

 Burchell, briefly described some of the characteristics of 

 this group of rocks a hundred years ago and more, the 

 first attempt at a systematic investigation was made by 

 G. W. Stow, 1 who, in spite of an error by which he con- 

 founded the volcanic group high up in this system with 

 the Pniel volcanic beds lying unconformably below it, 

 made a great advance in the knowledge of the geology 

 of Griqualand West. 



The system, as developed in Cape Colony, is divided 

 up into three series : 



r Upper Griqua Town beds. 



Middle Griqua Town or 

 Griqua Town series - 



Ongeluk beds. 



^ Lower Griqua Town beds. 

 Campbell Band series. 

 Black Beef series. 



A. THE BLACK BEEF SERIES. 



The Black Beef series, mainly a sandstone group 

 with subordinate beds of conglomerate, is taken to be 

 the base of the system, as there is undoubtedly an un- 



i Q. J. G. S., xxx., 1870, p. 581. 



