They did not land upon
either the islands or the main; but two kinds of rock, one with strata
and the other without, were plainly discernible. That without strata
formed by far the largest part; it appeared whitish and shining, was
certainly a quartz, and probably a granite. The layers of the rock with
strata were of various dark colours, and perfectly distinct.
It was evident, that land so much exposed to the violence of extensive
oceans must have undergone some very material changes, by the incessant
attrition of their vast waves. Two of the isles, either from this or a
more sudden cause, have so far deviated from their centre, that their
parallel strata form angles of between sixteens and eighteen degrees in
one instance, and in another between twenty-five and thirty degrees, with
the horizontal line. But it is difficult to explain, by the action of
water, how a large block of the white stone without strata is caused to
overhang an almost perpendicular corner of one of the islands, which
beneath that block consists of the dark coloured stone lying in strata.
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