126 
THE GEOLOGIST. 
&C.1 In regard to Etna, he leaves M. de Beaumont's misrepresentations of fact 
to be dealt with by Sir C. Lyell, only remarking that, on M. de Beaumont's own 
showing, the portion of Etna which he supposes to have been upheaved, is 
positively " encnisted with a coating of lavas." 
The inapplicability of the elevation theoiy to the Cantal, Mt. Dore, and Mezenc 
in France, is then shown, inasmuch as, by M. de Beaumont's own admission, the 
angle of slope of their l)asaltic and trachytic beds is even less than that of the 
recent and acknowledged lava-flows in the same district. Finally, he asks what 
has become of the products of the repeated eruptions of volcanos, if they have not 
accunndated in the course of ages into the mountains which we find there, com- 
osed of irregidar alternating beds of lava and conglomerate just such as we see to 
e erupted from the central orifices ? 
The author next shows that the upheavalists have no correct idea of the 
mode of formation of craters, which are not formed, as they assert, at one blow, 
by a single exjjlosion, like the bursting of a bubble, or of a mine of gunpowder, 
but by the reiietition of explosions or flashings of steam from the smface of 
ebullient lava within the volcanic vent (like those of a colossal Perkins's steam- 
mortar), continued for weeks and months, or more, by which the mountain is often 
ultimately eviscerated, its summit and heart being blo'nTi into the air, and scattered 
in fragments or ashes around— )!o< foiuidering into the cavity and remaining there 
as they represent. He instances the great crater of Vesuvius formed under his 
eyes in 1822 by explosions lasting twenty days ; and judging from the quantity of 
fragmentary matter then ejected and falling around, comparing it with the far 
greater quantities tin-own up occasionally l)y emptive paroxysms in other quarters 
of the globe, he asserts his belief that in the latter cases craters may lie, and are, 
formed of several miles in diameter, nothing remaining of the whole mountain 
except the wreck of its base, as we see in Santorini, the Cirque of Tenerifle, and 
so many other circular clitt-ranges surrounding extinct or active volcanic vents. 
He expresses his astonishment that Von Buch and Humboldt should have sup- 
posed Vesuvius to have " sprang up like a bubble in one day, just as we now see 
it," in the year 79 A.n., and not to have increased since ; and shows that even 
within the last hundred years great changes have taken jilace in the form of that 
mountain, and that the relation of Pliny of the iihenomena witnessed by him is 
inconsistent with the idea of upheaval, and demonstrative of the occurrence of an 
eruptive paroxysm by which the upper part of Sonnna was blown by degrees into 
the air, and the crater of the Atrio formed, in which the subsequent eruptions of 
eighteen centuries have raised up the cone of Vesuvius. 
In recapitulation, the author declares that the characters of all volcanic moun- 
tains and rocks are simply and naturally to be accounted for liy their eruptive 
origin, the lavas and fnigmentaiy matters accumulating round the vent in forms 
determined in great degree by the more or less imiierfect fluidity of the former, 
which, as in the case of some trachytic lavas, glassy or spongy, may and do con- 
geal in domes or bulky masses imniediatelv over, or in thick beds near the vent, 
or, as in that of some basaltic lavas, may flow over very moderate declivities, to 
great distances ; and consequently that the upheaval- or elevation-crater theory is 
a gi-atuitous assumption, unsupported by direct observation and contraiy to the 
evidence of facts. He concludes by representing its continued acceptance to be 
discreditable to science, and an impediment to the progi-ess of sound geology, 
inasnnich as false ideas of the bubble-like inflation, at one stroke, of such moun- 
tains as Etna or Chimburazo must seriously affect all our speculations on Geological 
Dynamics, and on the nature of the subterranean forces by which other mountain- 
ranges or ct ntiiients are formed. 
