Vol. 54.] 



GEOLOGY OF THE WITWATERSRAND, ETC. 



course, namely, east, on the properties of the French Rand and 

 Champs d'Or Gold Mining Companies. On these properties the 

 Main Eeef Series is known as the ' Bothas Series,' while the 

 Kimberley Series is called the ' Battery Reef Series.' Traced still 

 farther, the beds swerve to the south through Randfontein and 

 Uitvaalfontein, until again cut off by an east-and-west fault, which 

 carries them on to the farms Droogeheuvel, whence they may be 

 followed south-west through Haartebeestfontein and Witfontein. 



Examined in detail in the mine-workings, the beds are found to 

 have suffered numerous minor dislocations by cross-courses, the 

 faulting being in many cases accompanied by igneous intrusion (as 

 in fig. 2). Several instances of overthrust and reduplication by 



Fig. 2. — Upthrow fault in tJte Crown Reef Mine. 



Scale of Feet 



100 200 



J ' ' ' 



300 400 Son 

 — I 1 ! I 1 



reversed faults, coursing with the strike of the beds, have also been 

 observed, reference to which will be made in the sequel. With 

 regard to gold-contents, the best section of payable ore extends for 

 about 10 miles in the central part of the Rand (near Johannesburg). 

 Outside this section occasional patches of payable or even rich ore 

 are found, but the general average is low-grade, and there are 

 many places where the auriferous conteats are not sufficient to 

 repay working. 



Several good sections through the Witwatersrand Beds have 

 been obtained by deep borings in different parts of the Rand. 

 These have been carried down to various depths, in one case 

 exceeding 3000 feet, and the results obtained show a remarkable 



g2 



