File:The Quarterly journal of the Geological Society of London (12981206593).jpg

524
PROCEEDINGS OP THE GEOLOGICAL SOCIETY. .Feb. 2,
The broken edge of the new crater's rim showed, still smoking,
sections of the lava- currents which, for some years, I myself had
watched successively flowing down the sides of the cone from minor
eruptions at its summit, and leaving soHd ribs of lava- rock upon its
surface-slopes, up which ribs I often cHmbed the cone. I had,
through the same period, seen an abundance of fragmentary lava and
scoriae discharged from various upper mouths, forming hillocks and
protuberances upon the rude platform which then surmounted the
cone ; one of which minor cones, measuring no less than 450 ft. in
height, was thrown up within three months in the early part of that
year (1822), a fact confirmed by the testimony of MM. Monticelli and
Covelli. And with this positive experience of the rapid growth under
my own eyes of the cone of Vesuvius within two or three years only
of comparatively moderate activity, and with the knowledge derived
from authentic records of some fifty or more paroxysmal eruptions,
many of them of greater violence, having occurred from this same
volcanic vent during the last eighteen centuries, can I entertain any
respect for a theory which tells me that the entire mountain was
formed, just as we now see it, in the year 79, by some unintelligible,
or at least unexampled, process — that it has not since that epoch
grown at all by the accumulation of the erupted matters, whether
lavas or scoriae — ^nay, that it has rather diminished than increased in
bulk and height from the time of its original inflation ? Eor that is the
assertion put forth by de Buch, and endorsed by M. de Humboldt !
Have we not also a right to ask those who refuse to believe the still
larger volcanic mountains of either hemisphere to be built up from
the accumulated lavas and fragmentary ejections of their repeated
eruptions, what else can have become of all these erupted matters ?
Many such volcanos are known to have been in frequent or habitual
eruption during even recent historical times, ejecting vast quantities
of scoriae, pumice, and ashes, and enormous streams of lava from
their central crater or its immediate vicinity. It is fairly pre-
sumable that for long previous ages similar eruptions had been taking
Eig. 9. — Ideal section of a Volcanic Cone, formed of the products of
repeated Eruptions.
place from the same vents. The eruptionists admit that a single