380 W. M. DAVIS — OBSERVATIONS IN SOUTH AFRICA 



partures in South Africa were effected on the days, practically on the 

 hours, that had been planned and published before the oversea party 

 had left England. 



PHYSIOGRAPHIC DIVISIONS OF SOUTH AFRICA 



The greater part of the region that we traversed is included in the 

 extensive highland or high-standing peneplain, with an altitude of from 

 4,000 to 6,000 feet, which forms the body of the South African interior. 

 Over the greater part of this region, 1,000,000 or more square miles in 

 extent, there has been no strong deformation for many geological ages, 

 although Passarge (page 596) states that there are some Mesozoic graben 

 in the Kalahari region. The southern part of the highland region has 

 been still quieter, for if the slow and gentle depression by which the 

 Karroo basin of heavy Mesozoic deposition was formed be neglected, as 

 it may well be because of its equable nature, there has been no consider- 

 able deformation since pre-Devonian times. Much of this district is 

 commonly spoken of as the "Veld" (pronounced felt) ; its higher parts 

 are the High Veld. It is characteristically treeless over large areas, but 

 in the north, where tree-growth occurs, it is called the Bush Veld. Its 

 wet season is the summer of the southern hemisphere, when a rainfall of 

 about 30 inches is recorded, much of it falling in heavy, short-lived 

 showers, and causing sheetfloods on the unchanneled slopes and rapid 

 changes of volume in the rivers. As the time of our visit fell near the 

 end of the winter season, the Veld was dry and brown when we crossed it. 



A number of subparallel mountain ridges, trending east and west, 

 occupy a belt of country some 60 or 80 miles in width across the southern 

 end of the continent. These are built chiefly of Paleozoic formations 

 that were crushed into folds in Mesozoic time and afterward greatly 

 eroded. In the absence of other general name, they will be here called 

 the Cape Colony ranges. Associated with the east and west ridges are 

 others of smaller dimensions, trending north and south, one group in 

 the southwest corner of the continent and another of less pronounced 

 relief along the eastern coast in Natal. The southern part of this moun- 

 tainous belt, near the coast, lies in the subtropical belt of the southern 

 hemisphere, and receives its rainfall chiefly in the southern winter season, 

 when the cyclonic areas of the prevailing westerly winds have a more 

 northerly path than in the other half of the year; but they seldom reach 

 the inner part of the mountainous belt, known as the Karroo, which is 

 therefore dry all the year round. The highest of the east and west 

 ridges, which reach altitudes of some 6,000 feet, aid in determining a dry 



