Geological History of the Gouritz Biver System. 381 



imposed one as regards the folded country between the Karroo and 

 the ocean; that is, it worked its way down from the surface (of 

 Uitenhage sediments), upon which the main streams were con- 

 sequent, to a highly diversified surface, the result of a former period of 

 denudation, so that the rivers which thus maintained their courses 

 came to have no direct relations to the structure of the country over 

 which they ran after the removal of the unconformable Uitenhage 

 rocks. The evidence which allows us to arrive at this conclusion is 

 almost entirely derived from the remnants of the Uitenhage sedi- 

 ments, which once stretched much further in every direction than 

 they do now. If we, in imagination, remove these remnants of 

 Uitenhage rocks we do not make a profound alteration in the 

 structure of the country between the Karroo and the ocean, we merely 

 lay bare the underlying rocks of the Cape formation, and still older 

 rocks ; and one result would be a country like the Ladismith Karroo, 

 and an extension of the George granites and slates to meet the 

 Kuggens of Swellendam ; but another result, and the one I wish 

 to call attention to, would be that we should have no clue from 

 the geology of the country to the history of the Karroo rivers. 



The rising of the area south of the Karroo, after the deposition of 

 the Uitenhage rocks, altered the relative heights of the watershed 

 and of the southern area, so that at some points the latter is to-day 

 higher than the former, but the elevation of the southern area took 

 place so slowly that the main rivers were able to cut down their 

 valleys as the land rose, and were never dammed back or 

 diverted. 



The Buffel's River, which traverses the Zwartebergen below 

 Laingsburg, turns sharply to the east at the confluence of the Touw's 

 River after traversing rather more than half the distance between the 

 Zwartebergen and the Langebergen, and then flows through the latter 

 range together with the Gamka River. The Buffel's River thus 

 traverses the Langebergen some twenty-five miles further east than 

 would be the case if it had taken a direct course to the sea instead of 

 turning east to join the Gamka. On the theory we have adopted to 

 explain the origin of the Karroo drainage, one would expect the 

 "duffel's River to have flowed across the folded belt south of the 

 Zwartebergen more or less parallel to the Gamka. It is a noteworthy 

 fact that one of the lowest depressions on the crest of the Lange- 

 bergen is situated just on the line which should, according to the 

 hypothesis, have been taken by the Buffel's River. The depression 

 is Garcia's Pass north of Riversdale. At the present day the Kaffir 

 Kuil's River rises in the Langebergen, near Garcia's Pass, and 

 occupies the position of the lower part of the former course of the 



