The Forming of the Drakensberg. 69 



not in equilibrium, for the rising continued, and at the present day 

 the Orange Eiver and its tributaries flow in deep, narrow, winding 

 gorges at a depth of several hundreds of feet below the general 

 surface of the country, and a peneplain is in gradual process of 

 formation. 



Owing to our present lack of knowledge concerning the belt of 

 country between the Drakensberg and the Indian Ocean, it is 

 impossible to bring forward any information with regard to the 

 number of peneplains which are present in that area. It is known, 

 however, that the country rises in the form of a series of steps from 

 the coast inland. With each elevation the rivers tended to cut back 

 into the plain which they had just formed, and the crest of the 

 Drakensberg has thus retreated considerably. 



In this way a very precipitous face would be formed, and, as Mr. 

 Schwarz has suggested, the production of the escarpment would be 

 greatly aided by a heavier rainfall on the sea-ward face. It must be 

 noted that in Herschel and on the west side of Basutoland the 

 mountains rise quite as abruptly and to the same height as in the 

 Transkei, and I think that the most important factors in the pro- 

 duction of the long escarpment were, firstly, a large number of nearly 

 parallel streams leading from the mountains to the ocean ; and, 

 secondly, their much shorter courses. 



In cutting their way back the rivers on the south-east met with 

 no serious obstruction until they began to lay bare the great chain 

 of dolerite laccolites, extending north-eastwards from Engcobo 

 through Mount Ayliff. The igneous material proved rather diffi- 

 cult to erode, and hence the rivers have cut comparatively narrow 

 gorges in the dolerite instead of wide valleys. As the escarpment 

 retreated softer rocks were again met with to the north-west, and 

 readily eroded. 



Hence the line of laccolites is now marked by a tract of high-lying 

 ground separated from the present escarpment by a narrow belt of 

 much lower-lying country. At one time this long escarpment must 

 have extended westwards, probably beyond Steynsburg, but the 

 tributaries of the Orange Eiver have been very active in removing 

 material, and the watershed across Molteno and Wodehouse is now 

 very low ; in fact, just south of Dordrecht it is quite a flattish tract, 

 with isolated ridges and hills. 



What the Stormberg and Holle Spruits have accomplished in the 

 west the Long Kloof Eiver and Sterk Spruit are doing further east ; 

 and at the Barkly Pass there is a great gap where the Volcanic beds 

 have been removed, and from which the Cave sandstone is being 

 rapidly eroded. Similarly, in Matatiele, the pass at N'Quatsha's 



