110 Geography, Geology, 
In order to elucidate more clearly the above account of the 
different formations, and of their position and extent, I will 
give this short description, taken from the excellent Sketch of 
the Geology of eels by Dr. Daubeny. * 
The geology of Sicily may conveniently be divided into three 
parts, ceaoaine nearly with the three sides of the tr iangle 
which represents the figure of the island. It contains rset of 
the primitive, ee eS secondary or floetz, and tertiary classes. 
The first daoesion mill comprehend the rocks from Messina 
(or rather from Taormina) to Trapani. ‘These are primitive, 
transition, and secondary. ‘The first are only found at the 
north-east corner near Messina, where the prevailing rock 
appears to be gneiss. The transition constitute a chain of 
hills, extending obliquely from Melazzo, on the north coast, 
to Taormina on the east. They consist chiefly of mica side 
and clay slate, quartz rock, grey wacke, sandstone, and lime- 
stone. ‘The secondary iacke are found principally in a line 
parallel with the north coast. They consist, first, of red sand- 
stone, with beds of shale extending from Cape Orlando to 
Cape Cefalu; secondly, of a compact limestone, with beds of 
chert, jasper, and agate, which constitutes the Madonia moun- 
tains, and extends from Cefalu to Palermo, and from thence 
to Trapani. It perhaps corresponds with the magnesian lime- 
stone of England. 
The second division embraces the rocks that occur near the 
western coast, from ‘Trapani to Cape Passaro, the most 
southern point of the island, and consist chiefly of a series of 
formations which Dr. Daubeny is inclined to refer to the most 
recent epoch in the history of our planet, namely, that poste- 
rior to the formation of the chalk. These tertiary rocks con- 
sist, first, either of beds of blue clay and marl, containing 
much gypsum and selenite, sulphur, sulphate of str ontian, 
alum, and common salt ; secondly, of a calcareo-arenaceous 
breccia, replete with shells of a recent date, which is seen ex- 
tensively on the western coast, at the level of the sea, and, as 
we trace it south, is found to rest on the blue clay ; thirdly, of 
beds of shelly limestone, which occupy all the ‘south of the 
island, and alternate repeatedly with beds of volcanic matter. 
The third division, which takes in the line of coast on the east, 
from Cape Passaro to Taormina, exhibits indications of volca- 
nic action, occurring at very different epochs, from the lavas 
which flowed during the period at which the tertiary beds were 
being deposited, to the comparatively recent eruptions that 
have taken place from Mount Etna. But the hill, on which 
* See Jameson’s Edinburgh Philosophical Journal, vol. 13. 1825. 
