PHYSICAL GEOGRAPHY OF THE CAPE COLONY. 241 



Besides the above, there is a vast amount of intrusive Trap over 

 the country oecui)ied by groups 7, 8, and 9. Some, but not so 

 much, in the Ecca Beds. 



Of the four lowest of these subdivisions I can scarcely say anything, 

 and practically my story will begin with the Dwyka Conglomerate. 

 The portions of my sections which cross the rocks beneath that 

 horizon are taken from Bain or other authors, supplemented by such 

 passing observations as I was able to make en route; but I think I 

 saw enough on my journey into the interior to be convinced of their 

 general accuracy. 



I. LiTHOLOGICAL DeSCEIPTION OF THE KoCKS. 



(1, 2.) The slates, granite, and some dykes which traverse them, 

 of the neighbourhood of Cape Town (the "Malmesbury Beds"), 

 have been described by Dr. Cohen (Neues Jahrbuch fiir Mineralogie 

 &c., 1874, p. 460, 1880, vol. i. p. 96), and he also gives some 

 account of the Table-Mountain Sandstone, which, as far as I made 

 its acquaintance, I found to be a coarse massive grit. See also 

 Darwin, ' Voyage of the Beagle,' part 2, p. 148. 



(3.) The Bokkeveldt Beds are described by Bain as slates and sand- 

 stones. The fossils which he sent to England from these beds are 

 described by JSharpe and Salter (Trans. Geol. Soc. 2nd ser. vol. vii. 

 pp. 204-224). They both agree in thinking that their analogies are 

 with the Devonian of Europe. 



(4.) This groux3 consists mainly of massive white quartzites, with 

 bands of more thinly bedded quartzite and shale. I heard that 

 thin streaks of anthracite have been noticed in it near Grahamstown, 

 It is certainly very barren of fossils, and I could not get on the spot 

 any definite trustworthy account of fossils from it. But there are 

 reports that Lepidodendron and other Carboniferous plants have 

 been found. Bain says (loc. cit. p. 54) that a few vegetable im- 

 pressions and casts from these beds, first discovered by Dr. G. 

 Atherstone, appear to belong to Lejpidodendron. He also mentions 

 (p. 184) numerous specimens of Carboniferous plants from near the 

 Kowie Biver ; and it is stated (p. 184, note) that there is in the 

 Museum of the Geological Society a specimen of micaceous schistose 

 rock from the Kowie B-iver with Lej)idodendron-]ike impressions, 



[For the following notes I have to thank Prof. Eupert Jones. 

 Specimens from the Kowie were pronounced by Mr. E,. Etheridge 

 to be Carboniferous plants, and are so described in a letter from 

 Mr. H. W. Bristow addressed to the Crown Agent, 2nd May, 1870 ; 

 also in the Cape Town ' Standard Mail,' Nov. 18, 1869, Mr. Neate 

 mentions SigWaria, Stigmaria, Lejndostrohus, Halonia, Selaginites^ 

 in micaceous fissile shales, from Port Alfred. Prof. Jones also tells 

 me of Knorria from the Kowie Mouth at the Geological Society and 

 British Museum. He farther refers to Prosser, Trans. Phil. Soc. of 

 South Africa, vol. i, (1878) part 5.] 



(5.) Eor this rock I adopt Dunn's designation of "Dwyka Con- 

 glomerate'' in place of the old names of " Ciaystoue-Porphyry " 



