20 STRUCTURAL SYMMETRY OF THE COLONY 



reasonable doubt that on the sea floor between the 

 Gualana River and St. John's, first the Witteberg and 

 then the Bokkeveld beds disappear, owing to Pre-Dwyka 

 denudation, and that the Dwyka series rests upon lower 

 and lower members of the Cape system, so that in 

 Pondoland it lies directly upon the Table Mountain 

 series, just as it does north of the latitude of Van 

 Rhyn's Dorp. It is very probable that, as in the west, 

 the folds become less marked and practically die out 

 altogether in the same area that shows the thinning out 

 of the Cape system, so in the east the two changes go 

 on together. The comparison of the structure of the 

 northward termination of the folded belt in the west 

 and east of South Africa shows that this end of the 

 continent is built upon a more symmetrical plan than 

 might have been suspected from a mere inspection of 

 the geological map. 



The folded belt includes the more thickly populated 

 districts of the Colony outside the Native Territories. 

 Nearly all the various kinds of farming practised in 

 South Africa can be found within this region. The 

 most fertile and valuable land is that situated along the 

 larger rivers flowing through from the Karroo ; it is 

 enriched by the silt brought down by them. The 

 poorest soil is found on the sandstone mountains and 

 near the coast, where the natural vegetation is of the 

 kind known as " sour veld ". In a region so diversified 

 in climate and rocks as the folded belt, there are natur- 

 ally many varieties of soil, and we shall have an oppor- 

 tunity of noticing some of these in later chapters. 



