142 THE BOKKEVELD SERIES 



Bellerophbn, Nuculites and crinoids. The shales often 

 contain spherical or elliptical nodules, which are partly 

 filled with red or yellow ochre, sometimes used for 

 making paints with the addition of oil. Another variety 

 of nodule found in the shales is dark coloured inside, 

 and often contains rather well-preserved fossils. 



Some beds of the lowest shale group are coloured 

 black by the amount of carbonaceous matter in them, 

 and in places where the rocks have been intensely 

 crushed these beds are represented by graphitic slate or 

 schist, as on the north of the Pot Berg anticline near 

 Port Beaufort and near Bi/edasdorp. 



This subdivision usually forms a slope below a cliff or 

 very steep rocky ground formed by the second division, 

 the first or fossiliferous sandstone. The fossiliferous 

 sandstone is a dark-blue rock weathering deep red out- 

 side ; at some places the sandstone contains many fossils, 

 especially Spirifer and Leptocwlia, but at other localities 

 the sandstone is not nearly so fossiliferous. The beds 

 of red-weathering sandstone are separated by blue shales 

 very like those below and above this subdivision. The 

 thickness of the fossiliferous sandstone reaches 150 feet. 

 This rock can be seen north of the village of Ceres 

 especially on the road up the Gydo Pass, where many 

 fossils have been obtained from it. It is very often seen 

 as an escarpment, the steep face of which is directed 

 towards the Table Mountain sandstone. Such an es- 

 carpment occurs for a long distance, over fifty miles, on 

 the east side of the Cederbergen, where, owing to the 

 steep but constant dip of the beds south of Wupperthal, 

 the whole of the Bokkeveld series is exposed within a 



