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THE GEOLOGICAL HISTORY OF THE GOURITZ RIVER 



SYSTEM. 



By a. W. Rogers. 



(Read March 4, 1903.) 



(Plate III.) 



The main watershed of the Colony lies between those rivers which 

 flow north and west into the Atlantic, and those which flow south 

 and east into the Indian Ocean. The watershed is remarkably 

 simple and regular in form considering its length, in fact it 

 approaches the theoretical form assumed by the watershed of a 

 simple anticlinal uplift. Leaving the extreme south-west of the 

 Colony out of account, owing to some special conditions which have 

 complicated the problem there, we may trace the watershed from 

 the mountains near Tulbagh eastwards to the neighbourhood of 

 Matjes Fontein, then north-east along the Klein Roggeveld, 

 Komsberg and Nieuweveld Ranges, round and between the head 

 streams of the Gamka and Zak Rivers, thence across to the Sneeuw 

 Bergen, Achter Rhenoster Bergen, Kikvosch Berg, down consider- 

 ably to the south along the Bamboos Mountains, and thence along 

 the Stormberg to the Drakensberg. The general course is somewhat 

 east of north-east. The rivers with which we are at present 

 concerned are those which flow south from the Nieuweveld, 

 Komsberg, and Klein Roggeveld, and their tributaries, which enter 

 the ocean by the Gouritz River. 



The principal rivers of the drainage basin are the Buffel's, Dwyka, 

 and Gamka Rivers north of the Zwartebergen ; of these the two 

 latter join north of the Gamka Poort and flow through the Zwarte- 

 bergen together ; between the Zwartebergen and Langebergen the 

 Buffel's River is joined by the Touw's River, and the Gamka by the 

 Oliphant's River ; the two greater streams thus formed unite to 

 make the Gouritz, which traverses the Langebergen and continues 

 its course to the ocean without being joined by any considerable 

 stream south of that range. 



The Buffel's, Dwyka, and Gamka Rivers drain the Mordenaar's 



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