48 Transactions of the South African Philosophical Society. 



under tow, the bottom of the banks being first attacked, instead of 

 the usual gradual scouring all along the gradient. 



The basin of the Kammanassie Eiver is divided from the Long 

 Kloof by a range of hills ; looked at from the head of the pass from 

 Uniondale to Avontuur, the gravel-covered level is seen to be almost 

 continued over the dividing ridge, so that when the gravel was 

 formed erosion of the ridge had practically stopped. Since then, 

 owing to the uplift, the rivers have cut vigorously downwards, but 

 those in the Long Kloof seem to have arrived at such a state of 

 equilibrium that the water was actually stagnant. Near Avontuur, 

 for instance, one area is drained by a stream that has crept in from 

 the Kammanassie Eiver on the north ; another contiguous one has 

 been invaded by a river cutting back from the south, and now drains 

 straight into the ocean by the Keurboom's Eiver, while a third drains 

 eastwards to the Kouga. The Long Kloof is a narrow valley of 



Fig. 2. 



Section across the Long Kloof and Kammanassie River valley to show the 

 bevelling (P.P.) and the formation of a lower plain of erosion (p.) due 



to the obstruction of the stream marked by the Table Mountain 



Sandstone (T.M.S.) in he Long Kloof Mountains. 



Bokkeveld Beds hedged in with hills of Table Mountain Sandstone, 

 and there seems at first sight no reason why one large river should 

 not drain right away down the valley, as is the case with the 

 Oliphant's Eiver in Clanwilliam, which is similarly encompassed. 

 When, however, we find evidence of a former period of no flow — that 

 is, that the whole of the Long Kloof near Uniondale was converted 

 at the time into a swamp — we can understand how it is the side 

 streams from more vigorous river-systems have had time to eat their 

 way back through the dividing ridges, and steal each what it could 

 from this stagnant region. Directly the drainage of the Long Kloof 

 commenced, the plain that had been formed became eaten into by 

 ravines, and when these spread and spread, the plain with its gravel 

 covering became reduced to mere remnants, and hence we see little 

 table-topped hills, gravel-capped, in many places between Avontuur 

 and the George-Oudtshoorn road. Some of these invading streams, 



