288 
GEOLOGICAL APPEARANCES 
presented themselves on the slope of the Lion’s Head, over which 
large masses of granite are piled one upon another, are grouped side 
by side, or are scattered about in no definite manner. Some are evi- 
dently unconnected with the rock beneath, but many appear to be 
continuous with it. These rocks frequently exhibit large caverns, 
formed either by the action of water on their surfaces, or by their 
separation into different portions. Like the granite forming the base 
of the Lion’s Head, they are frequently traversed by large veins of 
quartz. Beyond these, and near the margin of the sea, I observed 
immense ridges of rock apparently of different colours, mingled toge- 
ther. I hastened to visit them, in the hope of meeting with an ex- 
ample of those instantice cnicis on which different geological theories 
are supposed to turn. In the descent leading to them I traced a vein 
of small-grained red granite for upwards of thirty feet running through 
the very large-grained granite which enters into the composition of 
the neighbouring mountains. Passing over this, I walked upon large- 
grained granite till I reached the sea. Then turning on my right, 
and proceeding in a line with the Lion’s Rump towards Cape Town, 
I found masses of black rock buried in fields of granite. Still ad- 
vancing, I gained a spot in which there was an extraordinary junction 
of granite and black rock, mixing together in such equal proportions 
that it was impossible to say which predominated. A little beyond, 
the black rock lay up in ridges from the sea into the granite ; and 
at length the granite disappearing, nothing but black rock was traced 
lining the coast for a considerable distance. The range of coast where 
these facts are visible, is known under the name of Green Point. 
In re-examining these appearances with greater closeness, I 
found the black rock, which I shall call schistus, uniformly in 
vertical strata. On a diligent examination, a large vein appeared 
passing through it, which, whether examined in its entire state or in 
hand specimens, seemed to be made up of curved layers, and much 
resembled fine-grained gneiss. This vein was very near a junction 
of the schistus with the granite, which is encountered when the 
Lion’s Head bears about south by east. The granite was here 
