i.S TRAVELS IN 
'Whetlier the deep excavations, that form the beds of these 
rivers, may be satisfactorily explained by supposing the tex- 
ture of the adjacent materials to have been of a loose and 
incoherent nature ; or, whether a greater antiquity than to 
many parts of the globe may not be assigned to the conti- 
nent of South Africa, on the whole surface of which there 
appears to be a remarkable fiimilarity, is a question on the 
merits of w- hich one would hesitate to give a prompt decision. 
•Eut, on comparing the great quantity of rain that annually 
falls at the Cape, a quantity far exceeding that in most parts 
of Europe, with the general scarcity of springs, the invention 
is naturally exercised in endeavouring to account for a phe- 
nomenon so unusual. The following observations may per- 
haps assist in explaining it. 
All the continued chains of mountains in Southern Africa 
are composed of sandstone resting upon a base of granite. 
This granite base is sometimes elevated considerably above 
the general surface of the country, and sometimes its upper 
part is sunk as far beneath it. In situations where the former 
happens to be the case, jiumerous springs are sure to be 
found, as in the instance of Table mountain, where, on every 
side, copious streams of pure limpid water, filtered through 
the immense mass of superincumbent sandstone, glide over 
the impenetrable surface of granite, furnishing an ample sup- 
ply to the whole town, the gardens, and the adjacent farms. 
But in all those places where the sandstone continues to de- 
scend below the surface, and the upper part of the granite base 
is sunk beneath the general level of the country, the springs 
that make their appearance are few and scanty. 
