Personal Narrative Of Travels To The Equinoctial Regions Of America During The Years 1799-1804 - Volume 1 - By Alexander Von Humboldt And Aime Bonpland.
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Its Formation Was Anterior To That Of The
Crater, Into Which, A Few Days After Its Opening, The Sea Made An
Irruption.
At Kameni, the smoke was not even visible till
twenty-six days after the appearance of the upheaved rocks.
Philosophical Transactions volume 26 pages 69 and 200, volume 27
page 353.
All these phenomena, on which Mr. Hawkins collected very
valuable observations during his abode at Santorino, are
unfavourable to the idea commonly entertained of the origin of
volcanic mountains. They are usually ascribed to a progressive
accumulation of liquified matter, and the diffusion of lavas
issuing from a central mouth.) on carefully reading the minute and
simple narrative, given by the Jesuit Bourguignon of the slow
appearance of the islet of the little Kameni, near Santorino; we
find that these extraordinary eruptions are generally preceded by a
swelling of the softened crust of the globe. Rocks appear above the
waters before the flames force their way, or lavas issue from the
crater: we must distinguish between the nucleus raised up, and the
mass of lavas and scoriae, which successively increases its
dimensions.
It is true that from all existing records of revolutions of this
kind, the perpendicular height of the stony nucleus appears never
to have exceeded one hundred and fifty or two hundred toises; even
taking into the account the depth of the sea, the bottom of which
had been lifted up: but when considering the great effects of
nature, and the intensity of its forces, the bulk of the masses
must not deter the geologist in his speculations. Every thing
indicates that the physical changes of which tradition has
preserved the remembrance, exhibit but a feeble image of those
gigantic catastrophes which have given mountains their present
form, changed the positions of the rocky strata, and buried
sea-shells on the summits of the higher Alps. Doubtless, in those
remote times which preceded the existence of the human race, the
raised crust of the globe produced those domes of trappean
porphyry, those hills of isolated basalt on vast elevated plains,
those solid nuclei which are clothed in the modern lavas of the
Peak, of Etna, and of Cotopaxi. The volcanic revolutions have
succeeded each other after long intervals, and at very different
periods: of this we see the vestiges in the transition mountains,
in the secondary strata, and in those of alluvium. Volcanoes of
earlier date than the sandstone and calcareous rocks have been for
ages extinguished; those which are yet in activity are in general
surrounded only with breccias and modern tufas; but nothing hinders
us from admitting, that the archipelago of the Canaries may exhibit
some real rocks of secondary formation, if we recollect that
subterranean fires have been there rekindled in the midst of a
system of basalts and very ancient lavas.
We seek in vain in the Periplus of Hanno or of Scylax for the first
written notions on the eruptions of the Peak of Teneriffe. Those
navigators sailed timidly along the coast, anchoring every evening
in some bay, and had no knowledge of a volcano distant fifty-six
leagues from the coast of Africa.
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