96 



DR. F. H. HATCH — GEOLOGY OF THE 



[Feb. 1898, 



faulting.' The latter assumption is by far the more probable.^ 

 But, whether caused by an elevation of the Archaean rocks or by the 

 sinking of the Cape Beds, the relative displacement has had a 

 marked effect on the latter, producing in them all the results of 

 strong dynamic influences. Lateral thrusting has turned the 

 Witwatersrand Beds sharply up on edge near their outcrop, and 

 several well-marked reversed faults have been observed in the 

 course of the development of the mines.^ 



Pig. 4. — Reversed Fault in the Witivatersrand Mine. 



^^'^ A^^ 



Scale of Feet 



100 200 300 too Boa 



A good example of these reversed faults is that which causes a 

 double outcrop of the Main Reef Series of conglomerates on the 

 properties of the Witwatersrand and Glenluce Gold Mining Com- 

 panies (see fig. 4), the distance between the two outcrops being 

 400 feet, and the vertical displacement 450 feet. Another fault of 



1 Prof. Suess, to whom I sent my map, writes me (Nov. 6th, 1897) : — 

 ' Your work shows in full clearness the picture of a curved, complex sjncHue 

 sunk into Archaean rocks between faults.' 



^ It may be noted that these dislocations are caused by strike-faults ; nume- 

 rous cross-faults have also been observed, but they produce displacements of a 

 normal type. 



