Geological Observations on South AmericaDarwin, Charles
Science
Geological Observations on South America
Darwin, Charles
Beagle Expedition (1831-1836); Geology -- South America; Mollusks, Fossil -- South America; Paleontology
Although in the foregoing discussion I have assumed the elevation to
have been horizontal, it may be suspected, from the considerable
seaward slope of the terraces, both up the valley of S. Cruz and up
that of Coquimbo, that the rising has been greater inland than nearer
the coast. There is reason to believe (Mr. Place in the “Quarterly
Journal of Science” 1824 volume 17 page 42.), from the effects produced
on the water-course of a mill during the earthquake of 1822 in Chile,
that the upheaval one mile inland was nearly double, namely, between
five and seven feet, to what it was on the Pacific. We know, also, from
the admirable researches of M. Bravais, that in Scandinavia the ancient
sea-beaches gently slope from the interior mountain-ranges towards the
coast, and that they are not parallel one to the other (“Voyages de la
Comm. du Nord” etc. also “Comptes Rendus” October 1842.), showing that
the proportional difference in the amount of elevation on the coast and
in the interior, varied at different periods.
COQUIMBO TO GUASCO.
In this distance of ninety miles, I found in almost every part marine
shells up to a height of apparently from two hundred to three hundred
feet. The desert plain near Choros is thus covered; it is bounded by
the escarpment of a higher plain, consisting of pale-coloured, earthy,
calcareous stone, like that of Coquimbo, with the same recent shells
embedded in it. In the valley of Chaneral, a similar bed occurs in
which, differently from that of Coquimbo, I observed many shells of the
Concholepas: near Guasco the same calcareous bed is likewise met with.
Public-domain text, read in full here on John Shaqi.
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