660 W. H. PENNING ON THE HIGH-LEVEL 
others hard, and with some thin slightly caleareous bands at in 
tervals. 
Hard grey fissile shales are exposed around the Koffy-Fontein 
and Jager’s-Fontein diamond-mines, and similar rocks about Philip- 
polis and the Orange river. 
The Kimberley shales continue over this district, and all the 
points are within 200 or 300 feet of the same level. Films only 
of coal and seams of hard shale with fossil ferns have been found 
near Kimberley. 
Towards the higher ground to the east the shales are somewhat 
different in character, at least as regards their weathering, due to 
the presence of a greater proportion of oxide of iron. Proceeding 
towards the Cape Colony, chocolate- and olive-coloured shales are 
met with; and Mr. Stow states that ‘‘ red-chocolate shale is found 
underlying a sandstone zone near Bethlehem” (Report, 1879, 
p- ol); 
At this higher level beds of a more sandy nature become frequent 
in the shales, which pass gradually upward into a series of fine 
and coarse sandstones with occasional thick-bedded grits and con- 
glomerates. It is inthis series of arenaceous rocks that coal occurs; 
it is therefore assumed that the boundary-line of these sandstones 
represents the western limit of the coal-bearing area, with possible 
outliers as already suggested. ‘This line passes from Bamboes Berg 
on the south, by Aliwal-North, to the Caledon river, west of Win- 
burg, and to the Vaal river above Bloemhof. 
In the northern part of the coal-field (see map, p. 658) the sand- 
stones rest directly on the ‘‘ Megaliesberg beds ;” therefore they 
overlap the shales in that direction (without any unconformity), as 
shown in the section (fig. 2) along le A B on the map. The northern 
extremity of the shales beneath the coal-bearing beds is probably 
somewhere about the junction of the Vaal and the Wilge rivers. 
Throughout both series of the ‘‘ Kimberley beds” and the coal- 
bearing sandstones, which for convenience may be provisionally 
termed the ‘* High-Veldt beds,” there are interstratified and intru- 
sive trap-rocks ; but as regards the shales, these have had little effect 
either upon their mineral character or their general horizontality. 
The persistent horizontality of these beds, both shales and sand- 
stones, is remarkable. The hills have been carved out of nearly 
level formations, the thickness of which may be approximately 
measured by mere differences in elevation. The fall in the base of 
the sandstones from near Middelburg (Cape Colony) to the Vaal 
river is equal to only ;4, of a degree—that is virtually level, and 
the shales have the same slight inclination (see fig. 3). The base of 
the shales at the Vaal river, near its junction with the Hart, is about 
3000 feet above the sea; that of the overlying sandstones, on the 
line of strike from that point, is 5300 feet. The difference, 2300 feet, 
is the minimum thickness of the shales as they pass there under the 
sandstones ; whether the old surface of the Megaliesberg beds beneath 
rises or falls makes no material difference. Towards the south the 
shales may be much thicker; it depends upon how far the Lower 
