1871.] STOW VAAL-EIVER DIAMO^TD-GEAYELS. 13 



thus, proeeediug from Dordrecht to Aliwal, we find the level of 

 the river at tiie latter place upwards of 4200 feet above the sea. 

 Thence to Bloemfontein there is a continuous rise from one step to 

 another, until the plateau upon which Bloemfontein is situated 

 attains an altitude of upwards of 5000 feet ; while the mountains 

 forming the dividing ridge between the heads of the various tribu- 

 taries that run into the Upper Nu Gariep, or Orange river, and 

 those that empty themselves into the Indian Ocean rise to a height 

 of upwards of 10,000 feet. 



The same continues to be the case in proceeding still further 

 northward, across the upper portions of the streams that flow into 

 the Ky Gariep, or Vaal. The ciilminating point of that part of the 

 Draakensberg which forms the boundary of the watershed of this 

 river is 7200 feet ; while the northern side of this same river- valley 

 is bounded by an elevated plateau, called Hooge Yeldt (fig. 4, a a), 

 said to be, in portions near Magalies-Berg, nearly 7000 feet above 

 the sea. 



These elevated mountain-ranges, and the more level plateaux 

 that are connected with them, form a vast but irregular semicircle, 

 with an outline of upwards of 500 miles ; and within these widely 

 separated j)oints all the drainage flows either into the Orange or 

 the Vaal river : but the extent of the successive plateaux of in- 

 creasing altitude is confined ■\vithin an equally irregular line, running 

 round the interior, of this semicircle. 



Beyond this line a vast denudation must have taken place, which 

 has been no doubt one of the principal causes of the very consider- 

 able lowering of the level along these river-basins towards the west. 

 This will perhaps be best explained, in the case of the Yaal, by a 

 reference to the diagram that I have drawn to show the relative 

 heights of the country (fig. 4), Here it will be seen that the plateau 

 of Bloemfontein, together with the mountains with which it is 

 associated, is the outer limit of the central portion of the elevated 

 tract of country I have described, and extends between the basins 

 of the two rivers. From this point towards the north-west, instead 

 of rising step by step towards the interior, as has been supposed, 

 the very reverse is the ease. It gradually descends for about 100 

 miles, until at Klip Drift, on the banks of the Yaal, its level is 

 1750 feet below that of Bloemfontein, or some 3498 feet above the 

 sea, an elevation of not 50 feet above that of Queenstown, which 

 is 280 miles further to the south, and about forty miles south of the 

 Stormberg. 



The great distance between Klip Drift and Pniel and the sources 

 of the Yaal Hiver makes the diflference of altitude almost imper- 

 ceptible to the casual traveller, as the Likwa (or Upper Yaal), rising 

 near the Ipoko, is 330 miles, and the head of the Klipstopel (or 

 Kapok, that is, Snow Eiver, as it is called by the Dutch) is 420 

 miles distant. 



The very considerable difference in altitude between these different 

 points is sufficient to show the immense amount of denudation that 

 has taken place. The fall must, of course, be still greater at the 



