THE GEOLOGICAL HISTORY OF THE COLONY 455 



renewed the downward cutting powers of the rivers and 

 restricted the stream erosion within narrow limits, so 

 that great parts of the old plains were permanently 

 abandoned. The change in the drainage system thus 

 effected was considerable in certain areas ; the water- 

 shed between the Olifant's and Baviaan's Kloof Kivers 

 now lies on a high-level gravel plateau, and before the 

 platform was cut the watershed may have been far from 

 its present position. 



At the present time the Dwyka and Gamka traverse 

 the Zwartebergen together by the Gamka Poort, and at 

 a point thirty miles below that gorge the Buffel's Eiver 

 joins them to form the Gouritz Eiver ; to do this the 

 Buffel's Eiver turns sharply to the east, away from 

 what one would suppose its proper course to have been ; 

 the depression on the crest of the Langebergen, called 

 Garcia's Pass, lies directly in the supposed normal 

 course of the river, so it is not unlikely that its upper 

 part was captured by a western tributary of the Gouritz. 

 This must, however, have happened before the high- 

 level plain was cut, for the summit of Garcia's Pass 

 lies higher than the terrace on the north flank of the 

 Langebergen. 



There are other terraces at lower levels than those 

 mentioned above, but to bring all these into order and 

 to place them in chronological sequence is at present 

 impossible on account of the lack of detailed informa- 

 tion as to their relative heights and distribution. 



The raised beaches and the limestone formed from 

 sand dunes now lying at considerable heights above the 

 shore and at some distance inland, must belong to one 



