Dr, Daubeng on the Geolagy of Sicily. “2u9 
three of such alternations occur within a few miles of the 
Cape. After this a pause seems to have taken place in 
the volcanic operations, for the calcareous rocks continue 
without interruption for a distance of almost thirty miles 
northward of the Cape, to a line nearly parallel with the 
town of Palazzolo, when indications of igneous action appear 
to recommence. 
The most numerous alternations, however, of these twa 
classes of deposits occur between the town of Lentini and the 
Mountain of Santa Vennera, to which, as illustrating the 
general structure of this district, 1 shall chiefly confine myself. 
_ Santa Vennera, the loftiest mountain in the south of the 
island, is capped with lava, full of cells, having that oval ar 
elongated figure eommon in rocks from which elastic vapours 
have been disengaged, whilst they were flowing in a current, 
Underneath it is a bed of compact limestone, full of minute 
and hardly distinguishable shells. At a still lower level on 
our descent towards Lentini, we meet with a second bed of 
voleanic matter similar to the first, and before we reach the 
town two other such alternations take place. 
At length, as we descend the last hill, which brings us 
thither, we find ourselves on a calcareous stratum singularly 
contorted, and dipping in a direction just the reverse of the 
preceding strata, which seem to be inclined towards the 
south-west. 
The volcanic nature of the beds which separate the ealea- 
reous deposits in this part of the island, being unquestionable, 
it becomes an interesting point to ascertain to what class ef 
formations the latter must be referred. 
In this inquiry the order of superposition will assist us 
little ; for, as the whole of these beds rest, as we have seen, 
on the Volcanic tuff of Cape Passero, so are they covered, in 
the rare instances in which any other kind of rock is seen 
above them, by the modern lavas of Mount Etna. The 
character, therefore, ef the shells they contain, seems the 
only method that remains to us for determining the date of 
the rocks, and here, fortunately, the information afforded, if 
not absolutely conclusive, leads, at least, to a probable cert- 
jecture. 
In the south of the island, indeed, between Cape Passero 
and Palazzolo, few fossils occur, and these not of a decisive 
character, unless the rock of Cape Passero itself be consider- 
ed an exception, where, together with the hippurite, a fossil 
Von. X.—No. ON 32 
