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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The Force Of The
Elastic Vapours Perhaps Formed This Natural Aperture, At The Time
Of Some Inundation Of Lava Thrown Out From The Crater.
The inside of this funnel indicates a volcano, which for thousands
of years has vomited no fire but from its sides.
This conclusion is
not founded on the absence of great openings, which might be
expected in the bottom of the Caldera. Those whose experience is
founded on personal observation, know that several volcanoes, in
the intervals of an eruption, appear filled up, and almost
extinguished; but that in these same mountains, the crater of the
volcano exhibits layers of scoriae, rough, sonorous, and shining.
We observe hillocks and intumescences caused by the action of the
elastic vapours, cones of broken scoriae and ashes which cover the
funnels. None of these phenomena characterise the crater of the
peak of Teneriffe; its bottom is not in the state which ensues at
the close of an eruption. From the lapse of time, and the action of
the vapours, the inside walls are detached, and have covered the
basin with great blocks of lithoid lavas.
The bottom of the Caldera is reached without danger. In a volcano,
the activity of which is principally directed towards the summit,
such as Vesuvius, the depth of the crater varies before and after
each eruption; but at the peak of Teneriffe the depth appears to
have remained unchanged for a long time. Eden, in 1715, estimated
it at 115 feet; Cordier, in 1803, at 110 feet.
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