514 J. w. Bbiws. 



highest portions. The two sections given in text-figs. 2 and 

 3 (pp. 516, 517) illustrate the two types. 



Immediately below the araygdaloids, a conspicuous sheet of 

 dolerite or basalt (it is difficult to say which it is), varying 

 from 50 to 300 or more feet in thickness, occurs ; and this 

 hard bed forms a protective cap for many of the upper foot- 

 hills (text-fig. 1, p. 515). The lavas have been totally 

 denuded from every part except the highest portion, Avhich 

 extends from the Mont aux Sources to the southernmost 

 boundary of Natal. 



The Cave Sandstones, Red Beds and Molteno Beds, the 

 downward succession of the Storniberg Series, form the 

 northern portion and are exposed in the same order on 

 the slopes facing Natal, below the amygdaloids. Sandstones 

 alternate with thin beds of shale. The Cnve Sandstones 

 usually form conspicuous cliffs, covered with alga3 and 

 lichens. 



The lower foothills which extend about thirty miles from 

 the main range consist of reptilian sandstones and mudstones 

 of the Beaufort Series. Below these again are the Natal 

 Coal Measures, which are usually considered to belong to the 

 upper Ecca Series. There is complete conformity between 

 all the divisions from the Cave Sandstones downwards — and 

 only a slight unconformity between the Cave Sandstones and 

 the overlying lavas. 



From the main range of mountains the chief rivers of 

 Natal have their source, and they have cut through the out- 

 crops of the various geological formations nearly at right 

 angles. The result is that Natal, as a whole, rises from the 

 sea to the Drakensberg in a series of terrace-plateaux. The 

 Drakensberg range forms the highest plateau. The vege- 

 tation on the steep edge of this plateau, which faces Natal, 

 differs considerably from the vegetation on the plateau itself, 

 i. e. in the interior (cf. the differences between the edges 

 and the surfaces of the lower terraces in Natal, as described 

 by the writer in the previously cited papers). Between the 

 rivers or between their main tributaries we have a system of 



