Q54 Dr. Daubeny on the Geology of Sicily. 
owe their peculiar characters to an admixture of trachyte 
with titaniferous iron. 
It would be inconsistent, however, with the limits of this 
communication, to-pursue the subject farther, as all general 
inferences, with regard to this class of substances, would find 
a more natural place in an essay on the Phenomena of Vol- 
canoes in genera 
To conclude then, it would appear that the Island of Sicily 
contains rocks of the primitive, transition, secondary, and ter- 
tiary classes. 
he primitive are only found at the north-east corner of the 
island, near Messina,.where the prevailing rock appears to 
be gneiss. 
The transition constitute a chain of hills, extending ob- 
liquely from Mellazzo on the north coast, to Taormina on the 
west. They consist chiefly of mica-slate and clay-slate, 
quartz-rock, gray-wacke, sandstone, and limestone. 
The secondary rocks are found chiefly in a line parallel 
with the north coast. They consist, Ist, Of red sandstone, 
with beds of shale, extending from Cape Orlando to Cape 
Cefalu. 2dly, Of a compact limestone, with beds of chert, 
Jasper, and agate, which constitutes the Madonia Mountains, 
anes extends Cefalu to Palermo, and from thence to 
Trepani. It perhaps, corresponds with the magnesian lime- 
ne of England. The tertiary rocks consist either o 
of blue clay and marl, containing much gypsum and selenite, 
sulphur, sulphate of strontian, alum, and common salt, 3dly, 
Of a calcareous breccia, replete with shells of a recent date, 
which is seen extensively on the western coast, at the level 
of the sea; and as we trace it south, is found to rest on the 
blue clay; or 4thly, Of beds of shelly limestone, which oc- 
cupy all the south of the island, and alternate repeatedly 
with beds of volcanic matter. 
e volcanic rocks of Sicily are, at least, of two epochs ; 
namely, Antediluvian, which alternate with calcareous rocks, 
in the Vai di Noto, in the southern part of the island. 5thly, 
Postdiluvian, which comprise the greater part of the lavas 
that have flowed, at different times, from Mount Etna. It is 
probable that this mountain was burning, at a period anteces 
dent to the time of Homer; and there are volcanic rocks at 
its foot, which seem to have been produced anteriorly to the 
commencement of the present order of things, . 
a 
