great mass was torn from the contiguous Mount Jaci, and
thrown down with a dreadful crash upon the plain. Immediately
afterwards, the sea, rising more than twenty feet above the level of
this low tract, rolled foaming over it, and swept away the multitude. It
then retreated, but soon rushed back again with greater violence,
bringing with it some of the people and animals it had carried away. At
the same time every boat was sunk or dashed against the beach, and some
of them were swept far inland. The aged prince, with 1430 of his people,
was destroyed.

_State of Stromboli and Etna during the shocks._--The inhabitants of
Pizzo remarked that on the 5th of February, 1783, when the first great
shock afflicted Calabria, the volcano of Stromboli, which is in full
view of that town, and at the distance of about fifty miles, smoked
less, and threw up a less quantity of inflamed matter than it had done
for some years previously. On the other hand, the great crater of Etna
is said to have given out a considerable quantity of vapor towards the
beginning, and Stromboli towards the close, of the commotions. But as no
eruption happened from either of these great vents during the whole
earthquake, the sources of the Calabrian convulsions, and of the
volcanic fires of Etna and Stromboli, appear to be very independent of
each other; unless, indeed, they have the same mutual relation as
Vesuvius and the volcanoes of the Phlegraean Fields and Ischia, a violent
disturbance in one district serving as a safety-valve to the other, and
both never being in full activity at once.

_Excavation of valleys._--It is impossible for the geologist to consider
attentively the effect of this single earthquake of 1783, and to look
forward to the alterations in the physical condition of the country to
which a continued series of such movements will hereafter give rise,
without perceiving that the formation of valleys by running water can
never be understood, if we consider the question independently of the
agency of earthquakes. It must not be imagined that rivers only begin to
act when a country is already elevated far above the level of the sea,
for their action must of necessity be most powerful while land is
_rising_ and _sinking_ by successive movements. Whether Calabria is now
undergoing any considerable change of relative level, in regard to the
sea, or is, upon the whole, nearly stationary, is a question which our
observations, confined almost en