PRE-CAPE ROCKS OF SOUTH AND WEST OF COLONY 49 



the rocks are obscured by superficial deposits. It is prob- 

 able that part of the junction is an unconformity ; but 

 part of it is certainly either a thrust fault along which 

 the Malmesbury beds have been thrust north-east or 

 eastwards over the younger rocks, or the unconformable 

 junction has been overturned so that the younger rocks 

 now dip towards the older. 



Above the conglomerates and grits of the lower part 

 of the series lie slates, sandy shales and sandstones, 

 which are cleaved only in the more highly disturbed 

 area. 



The shales and sandstones are met with on the steep 

 escarpment of the Bokkeveld Mountain, and in the 

 Doom River Valley. They are rather like the shales 

 and sandstones of the Bokkeveld beds, but the thick 

 groups of sandstone beds, so characteristic of the latter, 

 are not found in the Ibiquas series. 



Ripple markings are extremely well preserved in 

 many of the sandstones throughout the series, and point 

 to the deposition of the beds in shallow water. Large 

 tracks and castings of some worm-like animal are 

 occasionally abundant, but these are the only fossils 

 known from the series. The nature of the rocks seems 

 very favourable for the preservation of organic remains, 

 and they are more likely to yield recognisable fossils 

 than any other Pre-Cape rocks in the south and west 

 of the Colony. They are unfortunately situated in a 

 district which is thinly populated and difficult to get 

 at. The thickness of the Ibiquas beds must be very 

 considerable ; on the face of the Bokkeveld escarpment 

 over 1,500 feet of these beds are exposed, but the base is 



