THE ERUPTION OF ETNA. 
453 
lieved^ and all would be quiescent until tlie consolidation of 
the lava at places exposed to chilling, as in the crater and 
where the subterranean lava-source was thin, or the unequal 
action of the chemical forces leaving unmolten masses in the 
changing materials caused fresh obstractions, when the gases 
wmuld again be pent up until they had re-accumulated sufficient 
power to burst their barriers and release themselves by 
eruption. Around every existing volcano are burnt- out areas ; 
and distinct from the present foci, often in very distant regions, 
are regions where volcanic activity has long since become ex- 
tinct. May not this mean that the action has been taking 
place along the subterranean out-crop of those intercalated 
beds of mineral substances whose chemical decomposition 
and re-formation has given rise to the volcanic force ? 
We have been led to the present article by the recent 
eruption of Etna — the largest and most celebrated of 
European volcanoes. Upon a grand platform, composed of 
once molten ejectamenta (cinders, scorise, and lava), 9,000 feet 
above the sea (see Plate XVIII.), its principal cone (a), towers 
still another thousand feet, and from the lofty summit (10,874 
feet above the sea) of that fiery chimney the eye scans around 
the ^^Demoffis Yale,^^ and overlooks 900 miles of clouds and 
outspread scenery beyond. Beneath the snow-capped heights, 
whence Sicilians, Italians, and Maltese obtain their refreshing 
summer drinks, are three well-marked climatal zones girdling 
the mountains fianks — the desert, the wooded, and the 
highly cultured bands. In the midst of the highest snow- 
fields (x)y the darksome crater (a) rises steep, and smoke emit- 
ting from every pore — nine miles round at its base {m d) and 
three at its mouth (s o) — presenting in its inner funnel a deep 
unapproachable gulf, out of which, ever and ever, wreaths of 
heavy sulphurous smoke roll down its barren sides. In one 
place a rift of snow lies bedded between thick lava-streams, 
whose own ashes have formed the non-conducting layers that 
have preserved it from the heat of the molten river which 
flowed above; and everywhere, in the extensive caverns in 
the huge and rugged mountain mass, goats take shelter from 
the storms. 
Around the vast base of the whole gigantic pile — some 90 
miles in girth — a rich cultivated region extends, from six 
to eleven miles broad (except upon the north, where it 
scarcely reaches for a mile) covered with towns, villages, 
and monasteries, inhabited by more than a hundred thousand 
living souls, tempted mainly into their insecure proximity with 
the dangerous mountain by the luxuriant fertility of the soil. 
With the progress of the day, the deep shadow of the mighty 
hill — which at sunrise rules a line across the whole Sicilian 
2 H 2 
