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Transactions of the Boyal Society of South Africa. 
The palaeozoic valleys are intimately connected with the strike of the 
underlying formations, hence the majority of the river-courses strike 
south-westwards ; wherever the direction of the folding changes that of 
rivers is correspondingly altered, as, for example, around and to the west 
of the Doornberg where the strike of the rocks is now south-eastwards. 
Transverse valleys also occur, but are not so conspicuous or so important. 
The direction of the principal palaeozoic drainage lines is indicated in 
Fig. 1. ^ - ^ 
The sediments derived from the denudation of this palaeozoic land 
surface must have been carried southwards and deposited in that direc- 
tion. Since this process of denudation was terminated by the Dwyka 
glaciation, and since in the south of the Karroo there is a perfectly con- 
formable succession from the Cape into the Karroo system, the inference 
is obvious that this land surface was a source, and an important one too, 
of the sediments that formed the Cape system of rocks. 
It is not necessary to go into details regarding the physiography of the 
area during late Palaeozoic times ; this has been fully discussed elsewhere.''' 
Sufficient is it for our purpose to state that the surface was intensely 
glaciated, and then buried beneath the Karroo sediments during the 
Permian and Triassic epochs. 
Whether the Stormberg series was ever deposited over central and 
northern Cape Colony is a matter of conjecture ; the evidence so far is 
very slender, but if the view is correct that this series is represented in 
central and northern Transvaal, in Ehodesia, and in the Bechuanaland 
Protectorate, then the formation was in all likelihood laid down in this 
portion of Cape Colony as well. At the close of Stormberg times the 
Karroo strata were injected by innumerable sheets and dykes of dolerite 
over an enormous area. 
The post-Kaeroo Denudation. 
From the commencement of the Permian down to the Jurassic epoch 
at least the old drainage system lay dormant, so to speak, beneath a great 
pile of strata. Upon the surface of this " plain of deposition " the 
present drainage system of South Africa was initiated. According to 
Professor Schwarz f the determining factor in the stream directions was 
a "main watershed" extending from Cape Town to Delagoa Bay. This 
view has, however, been adversely criticised by Professor Davis, | while 
the author § has shown that in the Drakensberg area the drainage is 
* Eogers and Du Toit, " Geology of Cape Colony," chap, xiii., 1909. 
f E. H. L. Schwarz, Geographical Journal, xxvii., 1906, p. 265. 
+ W. B. Davis, Bull. Geol. Soc. of America, vol. 17, p. 387, 1906. 
§ A. L. Du Toit, Trans. S.A. Phil. Soc, xvi., pt. 1, p. 53, 1905. 
