192 COAL IN DWYKA 



was approached. To this view is opposed the fact that 

 the edge of the present basin is by no means coincident 

 with the original limit of the Dwyka ; for, as already 

 remarked, the beds must have at one time extended 

 much farther to the south, while in Gordonia there is an 

 outlier of immense size far away from the main outcrop. 

 Again, recent work has cast suspicion on the view held 

 by Dunn, and also by Hatch and Corstorphine, 1 that the 

 Vereeniging coals belong to the Dwyka series, and it 

 may ultimately prove that, as held by Molengraaff' 2 and 

 Mellor, 3 the Transvaal coal is of somewhat later age. 

 Even supposing for the sake of argument that coal did 

 exist below the Karroo, the possibility of mining it 

 would be very remote. In the Southern Karroo the 

 depth at which the top of the Dwyka would be reached 

 near Beaufort West must be some thousands of feet. 

 In the Northern Karroo it is found that great sheets of 

 dolerite have been intruded in the sedimentary rocks 

 along the horizon of the White band or on one a little 

 above or below it, a circumstance that is unfavourable 

 to the retention of useful properties by coal beds, should 

 they exist there. 



Fossils are scarce in this formation. A few specimens 

 of the small reptile Mesosaurus have been found in the 

 Kirnberley Mine, in Herbert, Southern Bushmanland, 



1 Corstorphine, G. S., " The Age of the Central South African Coal- 

 field," T. O. S. S. A., vi., p. 16. Hatch and Corstorphine, The Geology of 

 South Africa, 1905, pt. ii., ch. 1. 



2 Molengraaff , G. A. F., The Geology of the Transvaal, Edinburgh and 

 Johannesburg, 1904, p. 75, etc. 



3 Mellor, E. T., " The Position of the Transvaal Coal-Measures in the 

 Karroo Sequence," T. G. S. S. A., ix., p. 97. 



