256 J. w. BEWS. 



northwards there are the younger Cretaceous and Tertiary 

 formations. 



From this very brief sketch it will be seen that Natal is a 

 country with a moderately complex geological structure. It 

 descends steeply from the lofty Drakensberg to the sea by 

 a series of terraces. The main terrace levels may be taken to 

 be roughly as follows : 



First terrace (coast belt) up to 1000 ft. 



Second terrace „ 2000-2500 ft. 



Third terrace „ 3000-4000 „ 



Mountain regions 5000 ft. and upwards. 



These are indicated on the accompanying map, for which 

 I am indebted to Mr. A. Hammar. 



From the Drakensberg all the main rivers of Natal have 

 their source, and the river valleys have been deeply cut 

 through the successive terraces. In addition to the main 

 terrace system we therefore have a system of river valleys at 

 a low level, and ridges between them at a high level, and this 

 fact introduces still greater complexity into the conditions 

 affecting plant-life. 



The soil will naturally be found to vary according to the 

 rock from which it has been derived. On the tops of the 

 ridges between valleys it lies more or less in situ, the product 

 of the disintegration of the rocks underneath. In the river 

 valleys and vleis (marshes) the soil on the other hand has 

 been transported for a greater or less distance, though noAvhere 

 in Natal can such transporting be described as more than 

 local. 



Over the wide area covered by the Ecca series of shales 

 and sandstones the soils would be of the poorest description 

 were it not for the intrusive basic igneous rocks which occur 

 everywhere. Nearly every kopje is capped by a sheet of 

 dolerite. These trap rocks consist of felspar, augite, mag- 

 netite, etc., and give rise by decomposition to hasmatite, 

 limonite, and other iron oxides, magnesia, lime, soda, and 

 often potash. The quantity of lime, however, as shown by 

 analyses of soils, is nearly always very small, and the soils 



