This coal-field is therefore
sunk as far below the surface of the sea as Chimborazo is elevated above it
-- at a depth at which the Earth's temperature must be as high as
435??degrees F. Hence, from the highest pinnacles of the Himalaya to the
lowest basins containing the vegetation of an earlier world, there is a
vertical distance of about 48,000 feet, or of the 435th part of the Earth's
radius.
If we compare these subterranean basins with the summits of montains that
have hitherto been considered as the most elevated portions of the raised
crust of the Earth, we obtain a distance of 37,000 feet (about seven miles),
that is, about the 1/524th of the Earth's radius. These, therefore, would
be the limits of vertical depth and of the superposition of mineral strata
to which geognostical inquiry could penetrate, even if the general elevation
of the upper surface of the earth were equal to the height of the
Dhawalagigi in the Himalaya, or of the Sorata in Bolivia. All that lies at
a greater depth below the level of the sea than the shafts or the basins of
which I have spoken, the limits to which man's labors have penetrated, or
than the depths to which the sea has in some few instances been sounded (Sir
James Ross was unable to find bottom with 27,600 feet of line), is as much
unknown to us as the interior of the other planets of our solar system.
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