KLEIN ZWARTBERG AND WITTEBERGS 389 



establishment of the present relations of the interior highland to the 

 continental coastline, and that still further changes were spontaneously 

 introduced by the rivers themselves during the present cycle of erosion 

 then initiated. This subject is pursued somewhat further in an article in 

 a recent Bulletin of the American Geographical Society. 



THE KLEIN ZWARTBERG AND THE WITTEBERGS 



We had opportunity of seeing several of the Cape Colony ranges. close 

 at hand during the excursion in the Karroo with Mr Rogers, and it was 

 of special interest to note that the east and west mountains were usually 

 of anticlinal structure. The most striking example of this kind that 

 came within our observation was the Klein Zwartberg, the western end of 

 a long range of Table Mountain sandstones whose central and eastern 

 part is known simply as the Zwartberg, 6,000 or 7,000 feet in height. 

 This mountain was, to be sure, seen only at a distance of some 10 miles, 

 but it presented a striking resemblance to some of the anticlinal moun- 

 tains of Medina sandstone in Pennsylvania, even to the sharp-cut gap by 

 which Buffels river escapes through it southward — a close match to the 

 deep gap of the Juniata in Jacks mountain, central Pennsylvania. A 

 notable feature of the South African view was the absence of verdure on 

 the mountain slope. The whole surface seemed to be of bare gray 

 sandstone, trenched by the gorges of short resequent streams, this being 

 a strong contrast to the forest-covered ridges of Pennsylvania and Vir- 

 ginia. The effect of the Cape Colony ranges in walling off one lowland 

 belt from another was very marked; for while they were by no means 

 unsurmountable, a road over them would be difficult to construct and to 

 maintain and as difficult to use; hence the great economic importance of 

 the water gaps as roadways, already reduced to moderate grades by nat- 

 ural processes. The Buffels River notch through the Klein Zwartberg 

 is shown in the background of figure 6. 



The Witteberg ranges south of Matjesfontein and Laingsburg were 

 seen to better' advantage than the Zwartberg, for our route lay near the 

 northern base of one of them for a number of miles and crossed another 

 at two points. Their altitude is less than that of the heavier Table 

 Mountain sandstone ranges. They everywhere showed strong deforma- 

 tion, with frequent overturns and over thrusts toward the north. The 

 ridge next south of Matjesfontein (M, figure 1) fades away a few miles 

 farther east, where its anticlinal axis pitches gently underground, so that 

 its resistant sandstones and quartzites are succeeded in that direction 

 by weaker sandstones and shales, chiefly the lower members of the over- 

 lying Karroo system. A second range then comes into view, some 5 



