Ch.VII.] 
VAL DI CALANNA. 
85 
rising ground composed of the modern lavas of Etna. On 
our left, a lofty cliff, wherein a regular series of beds is 
exhibited, composed of tuffs and lavas,, descending with a 
gentle inclination towards the sea. In this lower part of the 
section there are no intersecting dikes, nor any signs of minor 
cones interfering with the regular slope of the alternating vol- 
canic products. If we then pass upwards through a defile., 
called the ' Portello di Calanna,' we enter a second valley, that 
of Calanna, resembling the ravine before mentioned, but wider 
and much deeper. Here again we find, on our right, many 
currents of modern lava, piled one upon the other, and on our 
left a continuation of our former section, in a perpendicular 
cliff from four hundred to five hundred feet high. As this 
lofty wall sweeps in a curve, it has very much the appearance 
of the escarpment which Somma presents towards Vesuvius, 
and this resemblance is increased by the occurrence of two or 
three vertical dikes which traverse the gently-inclined volcanic 
beds. When I first beheld this precipice, I fancied that I 
had entered a lateral crater, but was soon undeceived, by 
discovering that on all sides, both at the head of the valley, 
in the hill of Zocolaro, and at its side and lower extremity, 
the dip of the beds was always in the same direction, all slant- 
ing to the east, or towards the sea, instead of sloping to the 
north, east, and south, as would have been the case had they 
constituted three walls of an ancient crater. 
It is not difficult to explain how the valleys of St. Giacomo 
and Calanna originated, when once the line of lofty precipices 
on the north side of them had been formed. Many lava-cur- 
rents flowing down successively from the higher regions of 
Etna, along the foot of a great escarpment of volcanic rock, 
have at length been turned by a promontory at the head of the 
valley of Calanna, which runs out at right angles to the great 
line of precipices. This promontory consists of the hills called 
Zocolaro and Calanna, and of a ridge of inferior height which 
connects them. (See diagram No. 18.) 
