COAL-FIELDS OF SOUTH AFRICA. 659 
plateau, having a precipitous face to the south and east, and a gradual 
undulating slope to the north-west, carved into broad deep valleys 
and rounded hills. 
The south and east margin is formed by the Stormberg and the 
Drakensberg mountains, which have a general altitude ranging 
between 6000 and 8000 feet, with occasional peaks rising to 9000 
or 10,000 feet above the sea. They have a “drop” of about 2000 
feet, forming a precipice inaccessible, except by a few passes, on 
the seaward side. There are numerous minor ranges and spurs, 
more or less transverse to the direction of the main lines. The 
highest part of the slope west of the mountain has an elevation of 
from 4500 to 5500 feet ; it is called the ‘‘ High Veldt,” in the Trans- 
vaal, and forms the immense plains of the Orange Free State. 
Nearly all the chief rivers of 8.E. Africa rise in these mountains 
(as well as the Orange river, which flows west to the Atlantic 
Ocean), drawing their main supplies from the coal-bearing strata. 
The general contours of the area are shown upon the map by 
dotted lines, 3000, 4000, 5000, and 6000 feet above the level of 
the sea. 
This coal-bearing formation rests unconformably upon a series 
(or it may be more than one series) of rocks which, as regards the 
northern part of the area, are probably of Upper Paleozoic age, 
and have been described as the ‘“ Megaliesberg beds.” Towards 
the south-west it probably overlies what have been described as 
‘“‘The Lower-Karoo beds,” also with an unconformity. It has been 
called ‘“*The Upper Karoo;” but as the break between it and the 
‘“‘Lower Karoo” is of unknown extent, it has been considered 
advisable to term the shales which form the lower part of it, pro- 
visionally, the ‘‘ Kimberley beds.” 
The ‘‘ Kimberley beds” are a great series of argillaceous de- 
posits, with few arenaceous and still fewer calcareous beds. 
The base of the formation, as seen about the junction of the Hart 
and Vaal rivers, consists of hard greenish-grey shales, stained with 
oxide of iron. Quartzites belonging to older rocks are exposed in a 
valley a short distance to the north. 
In Kimberley diamond-mine the shales are exposed around the 
margin, and in shafts to a depth of 300 feet; they rest upon a 
mass of trap-rock, probably interbedded, and of unknown thick- ~ 
ness. ‘They are here black, dark grey, and indurated, rarely more 
than a few inches in thickness, and weather to various shades of 
erey, brown, and red. ‘There are also intrusive masses of diorite 
by which the beds have been locally disturbed—this, however, only 
for a short distance, and over the whole district they are virtually 
horizontal. 
About fifteen miles south-west of Kimberley, hard grey shales, 
in beds 2 or 3 feet thick, are seen in a quarry, whence this stone is 
taken for building-purposes. These have been indurated by con- 
tact with a dyke of trap rock. 
At the “ Blue-bank” Drift, across the ‘“‘ Riet river,” south of 
Jacobsdal, there is a fine exposure of dark-blue shales, some soft, 
