E. H. L. Schwarz — Plains in Cape Colony. 189 



was poured out at this time aud forms the Drakensburg ; this 

 thrust back the waters over the main watershed in what is 

 now called the Orange River. 



I have elsewhere* given my reasons for considering the old 

 Karroo plain, now elevated 6,000 feet above sea-level, to have 

 been one of original deposition. Similar plains may be formed 

 in inland lakes as well as in enclosed portions of the ocean, and 

 I think it should be definitely recognized that such a plain can 

 be and has been formed by giving such a surface the techni- 

 cal name of & plain of deposition to distinguish it from a plain of 

 denudation, qualifying the term by the adjectives marine and 

 freshwater, according to circumstances. Generally the term 

 also includes the contingency of block elevation. I believe the 

 greatest example of this form of plain is that of the pampas of 

 South America. Ordinary deltas would come under this cate- 

 gory as well. 



it* 



ammcLiiasfyte 



d£o 



itaws Tfolvc &£»v '~7fy/oe 2B<nrm/ 



c/cu>&Kf /tc^t* 



^^^SS^^^^M 



Fig. 3. The upper end of the Olif ant's River, Oudtshoorn ; showing 

 the 4000-foot archplain, P. The Cretaceous beds, R.E. and W.E., were 

 deposited on a plain at this level, were tilted and subsequently cut down to 

 the same level. Behind are the folded mountains with a remarkably straight 

 crest ; on the north, the Swartberg mountains show a similar crest, and these 

 two suggest that they once were part of a peneplain at that level ; the folded 

 ranges, however, are far younger than the original plain of deposition. In 

 the low ground is a temporary peneplain cut in soft Cretaceous beds and due to 

 ihe barring of the river further down. T.M.S., Table Mountain beds; B.V., 

 Borkkeveld beds (Devonian) ; R.E., Red (Enon) Conglomerate ; W.E., 

 White (Enon) conglomerate. 



(3) During the extrusion of lavas South Africa sank, to rise 

 again at the termination to its former level, now 4,000 feet 

 above the sea, so that there are two clearly marked levels at 

 this elevation, some cut in older rocks, and some cut in Lower 

 Cretaceous rocks which were deposited on the older 4,000-foot 

 level, were folded and tilted, and again eroded or planed down 

 (fig. 3). Both of these 4,000-foot levels extend far inland and 

 must have also been represented by coast plains at about the 



* Schwarz, K. H. L., The Rivers of Cape Colony, GeographicalJournal, 

 pp. 265-279 ; London, 1906 ; see also Baviaan's Kloof, a contribution to the 

 theory of Mountain folds, Addresses and papers, Brit & S. A. Association 

 for the Advancement of Science, pp. 56-67. Johannesburg. 



