Mr. Bain on the Geology of Southern Africa. 187 



spherical, and resembling cannon-balls or bomb-shells ; these balls I have never 

 found in any other locality. 



Having now described the claystone-porphyry along its whole line, I shall return 

 to Section No. 1 , where I have already entered on that part of the colony known as 

 the Great Karoo Desert, which, from the Praam Berg, in Hantam, to the Sunday's 

 River, in Graaff Reinet Division, scarcely contains the permanent residence of a 

 dozen families. It may be considered altogether as a great hill- studded plain, 

 bounded on the west by the Cedar Berg and Swart Rug, and on the south by the 

 Witte Berg, Great Swarte Berg, and Blauw Berg, very prominent mountain- 

 ranges. The elevated plateaux of Hantam, Roggeveld, Nieuwveld, and Snieuw 

 Berg form its inland boundaries. In the summer, with the few exceptions above 

 mentioned, it is quite uninhabited, being a perfectly arid desert ; but the autumnal 

 rains cause the vegetation to spring forth so rapidly, that in the course of a few 

 days it is (as if by magic) suddenly converted into a perfect flower-garden, and 

 yields abundant herbage for cattle and sheep, so that all the Boers from the sur- 

 rounding highlands descend to the plains below during the winter months, living 

 in tents, surrounded by their families, flocks, and herds in true patriarchal 

 simplicity. 



This immense desert, as well as the whole tract coloured by different shades of 

 green in the Map (Plate XX.), would appear from geological evidence to have been 

 once occupied by an enormous lake or sea. The fauna and flora of this perhaps 

 isolated inland sea are now represented by the plant-remains buried in its finely 

 laminated deposits, and by the singular family of Dicynodonts and other peculiar 

 ancient reptiles, who here sported about in a world of their own, 



I shall now proceed briefly to describe these Reptiliferous strata. 



The first or lowest deposit is a finely-laminated, blue, argillaceous rock, being 

 invariably the same all along the margin, from Hantam to the Great Fish River, 

 reposing conformably on the claystone-porphyry, and quite unaltered by heat. A 

 narrow band of soft white slaty rock succeeds to this, which is succeeded by an ex- 

 tensive bed similar to the first, but containing abundance of plant-remains*. 



The only fault I have ever discovered in this country is found among those 

 slaty beds where they begin to alternate with sandstones at Buffels River, as shown 

 in Section 7 (Plate XXL). Near this part also the rocks are very much contorted, 

 which does not appear to be the case where the three general sections pass through 

 the reptiliferous strata. 



In my communication of 1844, before the idea struck me of the lacustrine origin 

 of these rocks, I have already described the other divisions of the formation, which 



* The specimens from the Ecca Valley, in the collection of 1847, and a large stem of a plant found at 

 Potatas River, in the Western Karoo, now sent, will illustrate this part of the section. 



