116 Dr Daubeny on the Geology of Sicily. 
Before I quit the subject of the Palermo limestone, I must 
not omit a circumstance relative to the rock of Mount Pelegrino 
near that city, which seems to deserve notice. Notwithstand- 
ing the uniform compactness of this stone, wherever it has been 
recently quarried, we find it in those parts which have been ex- 
posed to the weather, honeycombed in an extraordinary degree, 
by holes of considerable size, which penetrate several inches be- 
low the surface, but indicate, from the gradual decrease of their 
dimensions, that the cavities were formed by the action of the 
weather sinking gradually into the substance of the stone. 
These cavities, in their size and appearance, reminded me of 
those which occur near the surface of a hard siliceous limestone, 
belonging to the oolite formation, found near Cirencester in 
Gloucestershire, which has obtained the local name of the Dag- 
ham alum-stone. 
This irregular disintegration of the surface is common, in a 
greater or less degree, to most limestones exposed to the weather ; 
but it would be interesting to discover, whether the greater size 
of the cavities formed in these two instances be derived from any 
peculiarity in the nature of the rock itself, or in the circum- 
stances under which it has been placed. 
With regard to the age of the Palermo limestone, I cannot 
speak with confidence, but I conceive, that the facts already 
stated, warrant me in considering it, for the present, as corres- 
ponding to the Zechstein of the Germans, and the Magnesian 
limestone of England; in corroboration of which, I may perhaps 
add, that most of the specimens contain magnesia, although not 
generally in very large proportion. 
All the high ground near Palermo is occupied by this ancient 
calcareous formation, but the valleys and coast are covered with 
a very different kind of material, which would appear to have 
been at one time of considerable thickness, as it constitutes hills, 
which, though they offer no comparison in point of elevation 
with those consisting of the compact limestone, are yet some 
hundred feet in height. 
The line of demarcation between this and the preceding rock 
is very distinctly marked by the character of the vegetation. The 
compact limestone, like that of the Appenines or of Nismes in 
the south of France, is chiefly adapted for the olive, and affords 
but a scanty pasturage, vegetation being obstructed by the frag- 
