434 
SOUTHERN AFRICA. 
of mountains ; but it is only the edge of simi- 
lar table land, identical with that on the mar- 
gin of which we stood. This presents the same 
mountainous appearance to a person coming 
from the West : the intervening valley is called 
Cassange, and through it flows the Quango and 
other rivers. 
" Only when we reached the declivity which 
forms the valley of the Cassange, could I per- 
ceive why all the rivers that flowed £L E., 
or 1ST. W., ran in much deeper valleys, than 
those which followed an opposite direction. 
The slopes down to the feeders of the Casai 
and Quango, are more than five hundred yards 
long, and pretty steep, while the beds of the 
branches of the Leeba are never more than ten 
yards below the level of the surrounding coun- 
try. The whole valley of the Cassange seems 
to have been a work of denudation, for on all 
sides the declivity presents the same geological 
peculiarities ; viz., a covering of brown hoema- 
tite, mixed with quartz pebbles, lying upon 
bright red friable clay slate. This, differing only 
in hardness and paleness of colour, continues to 
the bottom ; but, towards the centre of the val- 
ley, it takes the form of argillaceous schist. A 
detached mountain, seven or eight miles S. S. W. 
of Cassange, called Kasala, and having per- 
pendicular sides all round, possesses the same 
