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Darwin, Charles, 1809-1882

"The Voyage of the Beagle"

The
ground in many parts was fissured in north and south lines, perhaps
caused by the yielding of the parallel and steep sides of this
narrow island. Some of the fissures near the cliffs were a yard
wide. Many enormous masses had already fallen on the beach; and the
inhabitants thought that when the rains commenced far greater slips
would happen. The effect of the vibration on the hard primary
slate, which composes the foundation of the island, was still more
curious: the superficial parts of some narrow ridges were as
completely shivered as if they had been blasted by gunpowder. This
effect, which was rendered conspicuous by the fresh fractures and
displaced soil, must be confined to near the surface, for otherwise
there would not exist a block of solid rock throughout Chile; nor
is this improbable, as it is known that the surface of a vibrating
body is affected differently from the central part. It is, perhaps,
owing to this same reason that earthquakes do not cause quite such
terrific havoc within deep mines as would be expected. I believe
this convulsion has been more effectual in lessening the size of
the island of Quiriquina, than the ordinary wear-and-tear of the
sea and weather during the course of a whole century.


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