PRE-CAPE ROCKS OF SOUTH AND WEST OF COLONY 53 



has become a quartzite by the cementation of the grains 

 by quartz. Some of the quartzites contain numerous 

 grains of felspar, which has been determined under the 

 microscope to be microcline, rnicroperthite, orthoclase 

 and a plagioclase, varieties of felspar that occur in the 

 granitic rocks of north-western Van Khyn's Dorp. 

 Along the eastern side of Flamink Berg the Ibiquas 

 beds, steeply inclined, pass under the Nieuwerust beds, 

 and the same thing happens at Karree Berg and the 

 hills of Drie Kuil and Spitsberg. The Nieuwerust beds 

 at all these places lie at comparatively low angles, and 

 were evidently deposited unconformably upon both the 

 gneiss and the Ibiquas beds. 



Although the Nieuwerust beds are usually gently in- 

 clined, for their dip rarely reaches 20, they have been 

 affected by a group of faults with northerly and north- 

 westerly trend. The downthrow of these faults is 

 always on the east, and the maximum difference in 

 level between the two sides of any one of them is prob- 

 ably less than 500 feet. 



This area was also affected by faults previously to the 

 deposition of the Nienwerust beds; for the Ibiquas 

 group is faulted down against the granitic rocks and 

 the Malmesbury series, and these faulted junctions pass 

 under the Nieuwerust beds without apparently affecting 

 them. In the case of these faults also, the relatively 

 depressed area is on the east, but the faults are probably 

 planes of thrust, along which rocks have been pushed 

 eastward over the younger formation. Two small out- 

 liers of the Nieuwerust beds occur on Slag Kop near 

 Groot Klip in the north-west of Van Ehyn's Dorp. 



