Dr Daubeny on the Geology of Sicily. 109 
came action, occurring at very different epochs, from the lavas 
which flowed during the period at which the tertiary beds were 
in the act of being deposited, to the comparatively recent erup- 
tions that have taken place from Mount Etna. 
The physical structure of the more central portions of the 
island need not be entered into at present, as it will be described 
in the course of this paper, and may be collected sufficiently, for 
our present purpose, by an inspection of the accompanying map. 
The plan, then, according to which I propose to consider the 
subject, whilst it corresponds with one of the usual routes 
adopted by travellers, has the advantage of following the natural 
order of succession in which the rocks should be considered. 
Let us commence, then, with the neighbourhood of Messina, 
the only part of the island in which rocks of a granitic character 
occur. 
Ferrara, indeed, in his Account of Sicily, lays them down as 
consisting of true granite ; and my observations here were far too 
cursory to justify my contradicting him. 
I may, however, remark, that, in the places which I examined, 
the rock seemed to have the characters of Gneiss ; and this is the 
formation which probably extends on the Italian side of the 
Straits, if I may judge from the specimens I brought from 
the celebrated rock of Scylla, where the slaty character prevails. 
In this rock, the mica is sometimes silvery, sometimes dark 
coloured ; the quartz and felspar have the ordinary characters. 
These three ingredients are disposed in laminae, and the aggre- 
gate is penetrated by veins consisting of quartz and mica in 
large and distinct concretions. 
The rock also contains imbedded masses, consisting chiefly of 
a mixture of quartz and hornblende. 
The same formation, I believe, extends uninterruptedly along 
the northern coast, as far as Melazzo, where the little neck of 
land projecting into the sea, on which the castle and town have 
been built, is composed of well marked gneiss. 
Near the extremity, however, of the peninsula, on the sum- 
mit of the cliff*, and at an elevation of several hundred feet above 
the level of the sea, there is seen resting upon the gneiss a com- 
pact greyish Limestone, containing numerous shells, such as Tere- 
bratulse, Turbinites, and a profusion of Madreporites, principally 
