264 Dr Daubeny on the Geology of Sicily. 
may be their origin, must have a much older date assigned to 
them. 
In some of the beds, for instance, there is an uniform com- 
pactness, and a lithoide fracture, which seems to indicate the 
presence of a certain degree of pressure ; in others we may ob- 
serve the presence of olivine, either disseminated in minute crys- 
stals through the mass, as in basalt, or assembled in nests. 
The cavities are also frequently filled up with calcareous 
spar or with zeolites, j ust like the amygdaloids of more ancient 
strata ; and in some of the beds a tendency to a columnar ar- 
rangement is discernible. 
The explanation of these phenomena must be reserved for an- 
other occasion ; at present I have only time to advert to the facts 
themselves. 
The volcanic rocks just considered, may, in conformity with 
my friend Professor Buekland’s nomenclature, be termed Ante- 
diluvian *, as they have been all subjected to the operation of 
the same general cause to which the formation of the valleys 
must be referred. 
It is therefore plain, that no craters are to be expected to 
exist in rocks so circumstanced, although it has been erroneous- 
ly stated that there is one on Monte Vennera, and others on 
* In adopting this term, I mean to express no opinion with respect to the 
much- agitated question, as to the identity of the particular deluge recorded in the 
Mosaic History, with the cause to which the excavation of the valleys and the 
formation of beds of gravel are to be referred. 
That no cause, or combination of causes, now in operation, could be adequate to 
produce these effects, and that the best mode of accounting for them is to suppose 
the eruption and subsequent retreat of a vast body of water acting simultaneously 
over the whole surface of the globe, I am myself fully of opinion ; but that this 
event was the same with that deluge which we see alluded to in Holy Writ, is ob- 
viously a distinct question, and one which I forbear entering upon, as it belongs 
rather to the province of Theological than of Scientific discussion. I make these 
remarks, lest I should be accused of adopting a classification founded on hypothe- 
tical principles, whereas the expression of antediluvian and postdiluvian , here used, 
is merely meant„to imply, that the rocks so named were formed before or after the 
period at which the valleys were excavated, and may, therefore, be received by 
every one who agrees with Professor Buckland so far as to admit, that the latter 
effects were brought about by the simultaneous operation of one general cause, and 
not by a succession of partial ones. 
