oppage of immense fragments of drift-ice, a description perfectly
applicable to these modern Etnean flows. The thickness of the separate
beds of conglomerate or breccia which are seen in the same vertical
section, is often extremely different, varying from 3 to nearly 50 feet,
as I observed in the hill of Calanna.

_Flood produced by the melting of snow by lava._--It is possible that
some of the breccias or conglomerates may be referred to aqueous causes,
as great floods occasionally sweep down the flanks of Etna, when
eruptions take place in winter, and when the snows are melted by lava.
It is true that running water in general exerts no power on Etna, the
rain which falls being immediately imbibed by the porous lavas; so that,
vast as is the extent of the mountain, it feeds only a few small
rivulets, and these, even, are dry throughout the greater portion of the
year. The enormous rounded boulders, therefore, of felspar-porphyry and
basalt, a line of which can be traced from the sea, from near Giardini,
by Mascali, and Zafarana, to the "Val del Bove," would offer a
perplexing problem to the geologist, if history had not preserved the
memorials of a tremendous flood which happened in this district in the
year 1755. It appears that two streams of lava flowed in that year, on
the 2d of March, from the highest crater; they were immediately
precipitated upon an enormous mass of snow which then covered the whole
mountain, and was extremely deep near the summit. The sudden melting of
this frozen mass, by a fiery torrent three miles in length, produced a
frightful inundation, which devastated the sides of the mountain for
eight miles in length, and afterwards covered the lower flanks of Etna,
where they were less steep, together with the plains near the sea, with
great deposits of sand, scoriae, and blocks of lava.

Many absurd stories circulated in Sicily respecting this event; such as
that the water was boiling, and that it was vomited from the highest
crater; that it was as salt as the sea, and full of marine shells; but
these were mere inventions, to which Recupero, although he relates them
as tales of the mountaineers, seems to have attached rather too much
importance.

Floods of considerable violence have also been produced on Etna by the
fall of heavy rains, aided, probably, by the melting of snow. By this
cause alone, in 1761, sixty of the inhabitants of Acicatena were killed,
and many of their houses swept away.[57