Geology of the Cape Colon]/. 317 



siderable portion of the colony was traversed by the author, and, 

 owing to the clear atmosphere and the barrenness of the surface, 

 the rocks were unusually well seen. Much, too, had been ascertained 

 by previous observers. 



The grouping of the South-African rocks adopted was the fol- 

 lowing : — 



C Volcanic Beds, 9 d. 



a oi -u -d j J Cave Sandstone, 9 c. 

 9. Stormberg Beds j Eed ^^ Q ^ 



[ Molteno Beds, 9 a. 

 8. Karoo Beds. 

 7. Kimberley Shales. 



Great Unconformity. 

 6. Ecca Beds. 

 5. Dwyka Conglomerate. 



Unconformity. 

 4. Quartzite of the Zuurbergen, Zwartebergen, and "Wittebergen. 

 3. Bokkeveldt Beds. 

 2. Table-Mountain Sandstone. 



Great Unconformity. 



1. Slates and intrusive Granite of the neighbourhood of Cape 

 Town (Malmesbury Beds). 



Of the four lowest subdivisions very little was seen. The Bokke- 

 veldt Beds had yielded fossils referred to Devonian. The detailed 

 descriptions commenced with the Dwyka Conglomerate, which was 

 coarse, containing both rolled and angular fragments, the matrix, 

 which was ill bedded, resembling granitic detritus. Some of the 

 boulders suggested doubtfully the action of ice. The Ecca Beds 

 consisted of hardened sandy clays, without lamination, and often 

 weathering in spheroids, and resembling decomposed basalt or dole- 

 rite. These beds in the Ecca pass, north-east of Grahamstown, 

 were nearly 5000 feet thick. 



The Kimberley Shales were mainly grey and dark sandy shales, 

 with a few thin layers of argillaceous limestone. At their base a 

 conglomerate, resembling the Dwyka Conglomerate, was sometimes 

 found. The Karoo Beds were red and purple shales, with buff or 

 reddish sandstone containing much decomposed felspar. 



The Molteno Beds, also sandstones and shales, usually grey- and 

 dark-coloured, associated with grits and conglomerate, contained the 

 only useful coals of the colony. These coals were peculiarly lami- 

 nated and contained much ash ; the seams were destitute of sand- 

 stones and often eroded on the upper surface. These characters 

 might indicate subaqueous origin. Owing to the irregularity of the 

 seams, the views generally formed of the coal-resources of the 

 colony may be exaggerated. The upper subdivisions of the Storm- 



