5258 
Dr Daubeny on the Geology of Sicily . 
I allude to it, however, in this place, only on account of the 
vapour which is continually issuing from the clefts of the moun- 
tain at its summit, as an evidence, in common with the hot sul- 
phur-baths at its foot, of the chemical action going on at present 
among the constituents of the blue clay-formation. The dis- 
covery of this vapour, or rather, perhaps, its application to medi- 
cinal purposes, is attributed to Daedalus, who is said to have 
hollowed out the cavern in which patients are exposed to the 
hot exhalations At present, the name of Daedalus is super- 
seded by that of Saint Calogero, to whom a chapel is dedicated 
close to the spot from whence the vapour issues. 
The most southern point at which I recognised the blue clay 
was in the neighbourhood of Terranuova, where it gives place 
to a shelly limestone, alternating with a calcareous breccia, 
which at the time I was disposed to identify with the breccia 
seen everywhere associated with the preceding rock. 
At present, among the various omissions of which I accuse 
myself, but which the scantiness of accommodations, as well as 
the distraction of various objects, sometimes rendered unavoid- 
able, there is none I regret more than my not having fully made 
out the relations of the blue clay formation to the Limestone 
which succeeds it between Terranuova and Cape Passero. 
I am, upon the whole, inclined to view it as resting upon the 
latter ; but, on looking back to my notes, 1 must confess that I do 
not find myself authorised to state this, on any certain grounds. 
I may, however, express with more confidence, my belief, 
that the blue clay formation is of very recent date, belonging, 
probably, to the Tertiary Epoch ; and is not, as might be sup- 
posed, from the presence of salt and gypsum, related to the new 
Bed or Muriatiferous Sandstone of the north of Europe. 
There is nothing in the nature of its imbedded minerals to 
contradict such an opinion ; for gypsum and selenite, sulphur 
and sulphate of Strontian, are quite as characteristic of the Paris 
beds as of the secondary sandstone ; and common salt is said, by 
Steffens, to accompany the same rocks at the Segeberg in Hol- 
stein ; and, by Humboldt, in New Andalusia *. 
* See Humboldt’s Personal Narrative, vol. i. p. 262, English Translation, and 
Steffen’s Geogn. Aufsatze, p. 142, The description of the muriatiferous clay of 
New Andalusia corresponds exactly with what we know of the blue clay of Sicily, 
