Dr. Daubeny on the Geology of Sicily. 241 
the comparative ease with which it might be worked, it wag 
probably preferred for buildings in which the bulk of the 
materials, and the solidity of the structure, were the points 
chiefly considered. . 
Near Marecola and Sciacca, I observed in the rock certain 
spherical concretions, arising from the clusters of irregulay 
tubiform bodies, diverging from a common centre. J know 
not whether they are organic. 
This recent breccia is seen to rest upon a formation of 
quite a diilerent nature. ‘The superposition I first observed 
near the road between Mazzara and Castelvetrano, where 
the former rock is seen resting on a calcareous marl, devoid 
of shells, but replete with selenites. As we proceed south- 
wards, the gradual rise of this stratum brings more frequently 
to view the subjacent rock, which at Sciacca is seen at the 
level of the sea, whilst the breccia appears on the heights 
above, where the town itself is situate. The same thing 
occurs at Girgenti, where the breccia contains very fine tur- 
ritelle, trochi, and lunulites; and in the interior of the 
country, where all the most elevated spots are crowned with 
a similar loose shelly stratum, partly calcareous, partly are- 
naceous, always resting upon blue clay, and always full of 
petrifactions. _ 
Thus the heights of Castrogiovanni, (according to Ferrara, 
480 toises, or 2880 feet above the sea,) which overlook the 
valley of Enna, so celebrated in the mythology of the an- 
cients, and the fabled resort of their gods, are composed of 
this rock, resting upon a white calcareous stratum without 
shells, alternating with beds of marl, and this upon the blue 
clay which constitutes the bulk of the subjacent rock. Here, 
in addition to the preceding genera of shells, the sandstone 
contains specimens of the conus, buccinum, trochus, turbo, 
and mya. 
I must own, that some farther examination may be re- 
quired to establish the identity of the breccia found upon the 
hills in the interior of the island, with that on the coast be- 
tween Trepani and Selinus; but as I have seen the latter 
resting near Mazzara, on a rock decidedly the same with 
that on which the former is incumbent, and as the character 
of the rock, as well as its imbedded fossils, appear to coin- 
cide, I think myself warranted, for the present, in setting 
down.thé one as a continuation of the other. 
Vor, X.—No. 2. 3Y 
