rROCEEDIXGS OF GEOLOGICAL SOCIETIES. 
125 
1856, had it not been that Baron HuniLohlt, in the recently pubHshcd fimitli 
volume of his " Kosnios," applies the whole weight of his gi'eat authority to the 
support of the theory of upheaval in contradistinction to eruption as the vera 
caum of volcanic cones and craters, — a theory which the author, with Sir Charles 
Lyell, M. Constant Prevost, and many others, believes to be not merely eiToneous, 
but destructive of all clearness of api)rehension as to the character of the sul)ter- 
ranean forces, and the iiart which volcanic action has played in the structiural 
arrangement of the earth's surface. 
He showed, by reference to the works of Sjjallanzani, Dolomieu, Breislak, &c., 
that the early observers of volcanic rocks and phenomena, together with the 
unscientific world, looked upon volcanic cones and craters, whether large or small, 
as the result of volcanic eruptions ; but that of late years a new doctrine had been 
propagated by MM. Hinnboldt, von Buch, Elie de Beaumont, and Dufrdnoy, 
which denies altogether that volcainc mountains have been formed by the accumu- 
lation of erujited matters, and attributes them solely to a sudden " bubble-shaped 
swelling-up " of pre-existmg horizontal strata, — the bubble sometimes bursting at 
top and then leaving its uroken sides tilted up around a hollow (elevation- 
crater). 
The author expressed his belief that this riotion originated in Baron Humboldt's 
account of the erujition of JoruUo in IT-O!), in which (as the author showed in his 
work on volcanos of 182.5) a gTeat error had been committed, — the convexity of the 
Malpais and its five hills being simply a bulky bed of lava poured out on a flat 
plain from five ordinary cones of eruption, and the "homitos" conmion " fiuna^ 
roles " coated over with black mud prodnceil from showers of volcanic ashes mixed 
with rain-water. But the idea of a " bladder-like swelling-up " of horizontal strata 
into volcanic hills being thus started by von Humboldt, it was fiuther extended 
by M. von Buch ; and hence arose the " ele\ ation-crater " theory. 
The author next proceeded to show the inconsistencies of the advocates of this 
theory, who disagree among themselves as to tlie extent to which they apply it, — 
MM. Humboldt, von Buch, and Dufrenoy asserting both Somma and Vesuvius, 
the Peak of Teneriflfe, and all Etna, to be solely due to sudden ujiheval, while 
M. de Beaumont declares Vesuvius, the Peak, and the upper cone of Etna to be 
the products of eruption only. Again, while, except M. Bufi'enoy, all admit the 
minor cones and craters of Etna, Vesuvius, Lanzarote, and Central France to be 
eraptive, all declare the similar cones and craters of the Phlegrajan fields to be due 
only to upheaval. They offer no relialtle test liy which upheaved can be distin- 
guished from eruptive cones ; or, when they attempt this, differ again from one 
another, and even from themselves. Thus, Von Buch considers the extreme regu- 
larity of the slopes of Etna a proof of its upheaval. M. de Beaumont asserts 
regularity of outline to be the distinguisliing feature of an eruptive cone, and 
yet declares the upper and the lower portions of Etna, which are its least sym- 
metrical parts, to lie of eruptive origin, and the intermediate cone, the slope of 
which is extremely regidar, to have been uijbeaved ! In respect to the tuft-cones 
and craters of the Phlegr?ean fields, the scries from Somma to the Monte IS'uovo 
is so evidently of similar character, that, to a\ uid classing the first as an eruption- 
cone, the upheavalists have been driven to deny that the Monte Nuovo itself was 
the product of eruption, and even to assert tiuit it existed in the Roman era, and 
was oidy sprinkled with a few ashes by the eruption which, from all contem- 
porary authorities, threw it up in two days of the year 15.38 ! The author describes 
the circidar anticlinal dip of the strata of the ]\Ionte Nuovo and other tuft-cones of 
the Campi Phlegi-an as utterly inexplicable upon the theory of upheaval, while it 
is the natural result of the fall and accumulation of fragmentary materials pro- 
jected upwards by eruptions. 
He then disputes the tnith of J\I. de Beamnont's dogma, that lava cannot con- 
solidate into a solid bed upon a slope exceeding .5° or G°, and shows from number- 
less instances in Auvergne and the Vivarais, on Etna, Vesuvius, Tenerifle, &c., 
that bulky beds of lava have congealed on steep slopes, — in some cases, as for 
example in that of Jondlo itself, in the form of a massive promontory projecting 
far from the side of the cone of the crater from which it issued ; in others, wlieii 
liquidity was at the minimum, in that of a dome or bell (Bourbon, Puy de Dome, 
