IOO WATER SUPPIvY. — VEGETATION. 



levels up to spots destitute of the slightest indication 

 of water existing beneath, except a few rushes and a 

 peculiar kind of coarse reddish-coloured grass growing 

 in a hollow, which anciently must have been the eye of 

 a fountain, but is now filled up with soft tufa. In other 

 instances the indication of water below consists of the 

 rushes growing on a long sandy ridge a foot or two in 

 height, instead of in a furrow. A deep transverse cutting 

 made through the higher part of this is rewarded by 

 a stream of running water. The reason why the ground 

 covering this water is higher than the rest of the locality 

 is, that the winds carry quantities of fine dust and sand 

 about the country, and hedges, bushes, and trees cause 

 its deposit. The rushes in this case perform the part of 

 the hedges, and the moisture rising as dew by night 

 fixes the sand securely among the roots, and a height 

 instead of a hollow is the result. While on this subject 

 it may be added, that there is no perennial fountain in 

 this part of the country, except those which come from 

 beneath the quartzose trap, which constitutes the " filling 

 up " of the ancient valley ; and as the water-supply 

 seems to rest on the old silurian schists which form its 

 bottom, it is highly probable that Artesian wells would 

 in several places perform the part which these deep 

 cuttings now do. 



The aspect of this part of the country during most of 

 the year is of a light yellow colour ; for some months 

 during the rainy season it is of a pleasant green mixed 

 with yellow. Ranges of hills appear in the west, but east 

 of them we find hundreds of miles of grass-covered plains. 

 Large patches of these flats are covered with white cal- 

 careous tufa resting on perfectly horizontal strata of trap. 

 There the vegetation consists of fine grass growing in 

 tufts among low bushes of the " wait-a-bit " thorn (Acacia 

 detinens), with its annoying fish-hook-like spines. Where 

 these rocks do not appear on the surface, the soil consists 

 of yellow sand and tall coarse grasses growing among 

 berry-yielding bushes, named moretloa (Grewia flava), 

 and mohatla (Tarchonanthus), which has enough of aro- 

 matic resinous matter to burn brightly, though perfectly 

 green. In more sheltered spots we come on clumps of 

 the white-thorned mimosa (Acacia horrida, also A. ato- 

 miphylla), and great abundance of wild sage (Salvia 

 Africana), and various leguminosse, ixias, and large- 



