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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They No More Belong To The Soil Where
They Lie, Than The Feldsparry Lavas Of Etna, Seen In The Pavements
Of Hamburg And Other Towns Of The North.
The naturalist is exposed
to a thousand errors, if he lose sight of the changes, produced on
the surface of the globe by the intercourse between nations.
We
might be led to say, that man, when expatriating himself; is
desirous that everything should change country with him. Not only
plants, insects, and different species of small quadrupeds, follow
him across the ocean; his active industry covers the shores with
rocks, which he has torn from the soil in distant climes.
Though it be certain, that no scientific observer has hitherto
found at Teneriffe primitive strata, or even those trappean and
ambiguous porphyries, which constitute the bases of Etna, and of
several volcanoes of the Andes, we must not conclude from this
isolated fact, that the whole archipelago of the Canaries is the
production of submarine fires. The island of Gomera contains
mountains of granite and mica-slate; and it is, undoubtedly, in
these very ancient rocks, that we must seek there, as well as on
all other parts of the globe, the centre of the volcanic action.
Amphibole, sometimes pure and forming intermediate strata, at other
times mixed with granite, as in the basanites or basalts of the
ancients, may, of itself, furnish all the iron contained in the
black and stony lavas. This quantity amounts in the basalt of the
modern mineralogists only to 0.20, while in amphibole it exceeds 0.
30.
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