The Traps,
In Bursting Through, Had Broken Them Off And Preserved Them.
There Are, Besides, Ranges Of Hills In The
Central parts,
composed of clay and sandstone schists, with the ripple mark distinct,
in which no fossils appear; but as
They are usually tilted away
from the masses of horizontal trap, it is probable that they too
were a portion of the original bottom, and fossils may yet be found in them.*
-
* After dwelling upon the geological structure of the Cape Colony
as developed by Mr. A. Bain, and the existence in very remote periods
of lacustrine conditions in the central part of South Africa,
as proved by fresh-water and terrestrial fossils, Sir Roderick Murchison
thus writes:
"Such as South Africa is now, such have been her main features
during countless past ages anterior to the creation of the human race;
for the old rocks which form her outer fringe unquestionably circled round
an interior marshy or lacustrine country, in which the Dicynodon flourished,
at a time when not a single animal was similar to any living thing
which now inhabits the surface of our globe. The present
central and meridian zone of waters, whether lakes or marshes,
extending from Lake Tchad to Lake 'Ngami, with hippopotami on their banks,
are therefore but the great modern residual geographical phenomena
of those of a mesozoic age. The differences, however,
between the geological past of Africa and her present state are enormous.
Since that primeval time, the lands have been much elevated
above the sea-level - eruptive rocks piercing in parts through them;
deep rents and defiles have been suddenly formed in the subtending ridges
through which some rivers escape outward.
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