lands not having disappeared like Sabrina (see
p. 416), may have arisen from the emission of lava. If Jorullo, for
example, in 1759, had risen from a shallow sea to the height of 1600
feet, instead of attaining that elevation above the Mexican plateau, the
massive current of basaltic lava which poured out from its crater would
have enabled it to withstand, for a long period, the action of a
turbulent sea.

_Reflections on the earthquakes of the nineteenth century._--We are now
about to pass on to the events of the eighteenth century; but before we
leave the consideration of those already enumerated, let us pause for a
moment, and reflect how many remarkable facts of geological interest are
afforded by the earthquakes above described, though they constitute but
a small part of the convulsions even of the last forty years. New rocks
have risen from the waters; new hot springs have burst out, and the
temperature of others has been raised; the coast of Chili has been
thrice permanently elevated; a considerable tract in the delta of the
Indus has sunk down, and some of its shallow channels have become
navigable; an adjoining part of the same district, upwards of fifty
miles in length and sixteen in breadth, has been raised about ten feet
above its former level; part of the great plain of the Mississippi, for
a distance of eighty miles in length by thirty in breadth, has sunk down
several feet; the town of Tomboro has been submerged, and twelve
thousand of the inhabitants of Sumbawa have been destroyed. Yet, with a
knowledge of these terrific catastrophes, witnessed during so brief a
period by the present generation, will the geologist declare with
perfect composure that the earth has at length settled into a state of
repose? Will he continue to assert that the changes of relative level of
land and sea, so common in former ages of the world, have now ceased?
If, in the face of so many striking facts, he persists in maintaining
this favorite dogma, it is in vain to hope that, by accumulating the
proofs of similar convulsions during a series of antecedent ages, we
shall shake his tenacity of purpose:--

Si fractus illabatur orbis
Impavidum ferient ruinae.

EARTHQUAKES OF THE EIGHTEENTH CENTURY.

_Quito_, 1797.--On the morning of February 4th, 1797, the volcano of
Tunguragua in Quito, and the surrounding district, for forty leagues
from south to north, and twenty leagues from west to east, experienced
an undulatin