of great
part of that mass which had been once continued all over the island, as
high at least as the tops of the mountains, _i.e._ about a mile above
the level of the sea; we only differ in the time and agents which have
been employed in this Operation.

[Footnote 28: In the first part of this work, the distinction has been
made of true volcanic productions, and those which are so frequently
confounded with them; these last, though the creatures of subterranean
fire, and bodies which have been made to flow in a fluid state, are
clearly different from those masses of lava which have issued from a
volcano, as has been there described. I would only here observe, that,
according to this Theory, these bodies, which the Chevalier de Dolomieu
here represented as lava and volcanic production, must be considered as
unerupted lavas, which had been made to flow among the strata of the
earth, where other at the bottom of the sea, or during those operations
by which this land was erected above the level of the ocean.]

On the one hand, the Memoir now before us represents this great effect
as belonging to an unknown cause, so far as we are ignorant of that
grand _debacle_ or _catastrophe_ which changed the situation of the sea.
On the other hand, the Theory now proposed explains this operation,
of forming those conical mountains of Sicily, and hollowing out its
valleys, by known causes, and by employing powers the most necessary,
the most constant, and the most general, that act upon the surface of
the earth.

But, besides explaining this change of land and water by an unknown
cause, our author has here employed, for the removing of this mass
of solid rock, powers which appear to me no ways adequate to the end
proposed. The running of water upon the soft mud left by a river, given
here as an example, corresponds indeed in some respects with the form
of valleys; for, water acts upon the same principle, whether it makes
a channel through the subtile sediment of a river, or through the
travelled materials of a valley. But it is not here that there is
any difficulty in conceiving the rivers of Sicily to have shaped the
mountains and the valleys; it is in removing the masses of solid rock,
which covered the whole surface of this land in successive strata, that
any doubt could occur in ascribing the actual appearances of things to
the natural operations of the earth; but it is here particularly that
the retreat of the sea, in whatever