420 Transactions of the South African Philosophical Society. 



State and Transvaal borders. The shales of the series show good 

 examples of ripple-marking. 



A day's waggon trek * further on, just beyond the old magistracy 

 known as Allison's, we come to the first of the mountains or spurs 

 of the Drakensberg. These, together with several isolated high hills, 

 mostly flat-topped, are the remains of the extensive plateau from 

 which the Berg itself rises so precipitously. All these spurs are 

 therefore alike in their main features. Such variations as do occur 

 are due to the different thickness of the various beds of the cave 

 sandstone and the softer beds below the line of cliffs, and the 

 amount of weathering to which these have been subjected. 



These remains of the plateau owe their preservation to a protect- 

 ing sheet of dolerite, similar in appearance to the cappings found on 

 all the higher mountains of the Free State, such as Plaatberg, Pilani, 

 Majuba, &c. In no case is this sheet of dolerite above the cave 

 sandstone lower than from 5,900 ft. to 6,100 ft. above sea-level on the 

 Natal spurs of the Berg,t although dykes may occur at lower levels. 

 Wherever the sheet has disappeared through erosion (or did not 

 exist originally) the mountain or spur has been much lowered, and 

 is evidently undergoing faster weathering. 



The dolerite capping always rests on a thick, solid bed of cave 

 sandstone. After I had become familiar with the usual appearance 

 of this dolerite seen from a little distance, and the form its charac- 

 teristic mode of weathering gives to the tops of the hills and ridges, 

 I could tell miles away whether or not it would be found on the 

 summit of certain hills. 



Whereas in the Free State portion of the Berg the dolerite cap- 

 ping often shows a decided columnar structure, I found no indication 

 of columnar jointing in the part of the Berg under notice. It is, in 

 fact, seldom that a cliff-face can be met with in the dolerite. Steep 

 grassy slopes, and rounded hillocks and ridges covered with 

 weathered boulders of the dolerite, are the main features, and 

 present a marked contrast to the cliff tendency of the cave sandstone 

 below. As the Berg is approached one notices a strange sameness 

 in the formation of this upper part, or capping, of the spur ridges. 

 They all rise in terraces, and seen end on, many look like a suc- 

 cession of camel backs. 



In the canons of the Tugela and Little Tugela, close up to the 

 main wall of the Berg, cliff faces in the dolerite are exposed. In 

 one place on the Little Tugela nearly -400 ft. of perpendicular 



* A day's waggon trek in Natal is about twenty miles, 

 f The Drakensbergen are known locally as " The Berg." 



