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 that 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 color; 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 calcareous 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 aromatic resinous matter to burn brightly, though perfectly green.