PRIMITIVE ROCKS. 435 
lace, that pass over the summit, and are very re- 
markable in their appearance. Tv/o of them, 
placed near the central and highest point, are 
called the Diamond and PearL They are said to 
be of very coarse granular granite, but the hill is of 
sandstone. The Pearl rises about four hundred feet 
above the summit of the hill, and the circumfe- 
rence of its base is fully a mile. The Diamond is 
larger. The peninsula of the Cape of Good 
Hope contains a very thick bed of granite, which 
rises highest at its northern extremity, but be- 
comes gradually lower towards the south. In 
many places it is covered with clay slate, or it 
alternates with that rock, and transitions of the 
one rock into the other occasionally present them- 
selves. Cotemporaneous portions of granite occur 
in the slate, and if s;. te in the granite ; veins 
of granite traverse the granite ; and there are 
numerous examples of veins of granite shooting 
from the great bed into the adjacent clay slate 
strata. Quartz veins, sometimes of considerable 
thickness, run through the granite ; and veins of 
greenstone occur in the same situation. It is 
said that the clay slate alternates in beds with 
sandstone, and also passes into it. If the sand- 
stone really passes into the clay slate, and even 
alternates with it, it follows that these three rocks, 
viz. granite, clay slate, and sandstone, belong to 
the same class, and have been formed at the same 
