146 THE BOKKEVELD BEDS 



in the sandstone are usually in the form of impressions 

 left by the removal of the calcareous shells. The shells 

 themselves are rarely seen in the rock taken from near 

 the surface of an outcrop, hut when the rock from 

 a distance of some feet from a weathered surface is 

 obtained, the calcite shells are often seen in it. The 

 sandstone itself is slightly calcareous, but beds of 

 limestone are of very rare occurrence. 



Above the fossiliferous sandstone is the second group 

 of shales containing fossils, from 100 to 300 feet thick. 

 In the Cold Bokkeveld area the second group of shales 

 is distinguished by the presence of star-fish, but many 

 of the species that occur in the lower group are found 

 here also. Above them is the second sandstone, which 

 weathers into light-coloured outcrops, differing strongly 

 in this respect from the first or fossiliferous sandstone ; 

 it contains few fossils ; Spirifer is occasionally abundant. 

 The second sandstone is a thick group with many shale 

 beds, and in the Gamka Poort section reaches a thick- 

 ness of 400 feet. 



The third group of shales is about 350 feet thick, the 

 beds are often micaceous, and have thin quartzites 

 interbedded with them ; they usually contain few fos- 

 sils, Nuculites occurs in them at the Gamka Poort. 

 Near the Tunnel Siding on the Hex Kiver line this 

 group of shales yielded Lingula, Nuculites, crinoid stems, 

 a trilobite and Conularia, and also some badly preserved 

 plant stems resembling Lepidodendron. The third sand- 

 stone group (100 feet) with the shales above (300 feet), 

 as well as the fourth sandstone (100 feet) and the over- 

 lying shales (500 feet), have not been found to contain 



