same waste and wear, is going on everywhere, round
every coast. The rivers contribute their share to the great work of
change. Look at the sand-banks at the mouth of the Thames. What are
they, says Sir John Herschel, but the materials of our island carried
out to sea by the stream? The Ganges carries away from the soil of
India, and delivers into the sea, twice as much solid substance weekly
as is contained in the Great Pyramid of Egypt. The Irawaddy sweeps off
from Burmah sixty-two cubic feet of earth in every second of time, on an
average Sometimes vast amount of earthy materials is transferred from
one locality to another by river agency, as is the case in the deltas
of the Nile and the Mississippi.

These changes operate silently, continuously, and unperceived by the
ordinary observer; but Nature does not limit herself always and
everywhere to such peaceful agencies. At times, and in certain places,
she acts with startling abruptness and extraordinary violence. Let the
volcano and the earthquake attest the immensity of her power. Let the
earthquake tell how, within the memory of man, the whole coast-line of
Chili, for 100 miles about Valparaiso, with the mighty chain of the
Andes, was hoisted at one blow, and in a single night (November 19,
1822), from two to seven feet above its former level, leaving the beach
below the old low-water mark high and dry. One of the Andean peaks
upheaved on this occasion was the colossal mass of Aconcagua, which
overlooks Valparaiso, and measures nearly 24,000 feet in height. On the
same occasion, at least 10,000 square miles of country were estimated as
having been upheaved; and the upheaval was not confined to the land, but
extended far away to sea,--which was proved by the soundings off
Valparaiso and along the coast having been found considerably shallower
than they were before the shock.

In the year 1819, in an earthquake in India, in the district of Cutch,
bordering on the Indus, a tract of country more than fifty miles long
and sixteen miles broad was suddenly raised _ten feet_ above its former
level. The raised portion still stands up above the unraised, like a
long perpendicular rampart, known by the name of Ullah Bund, or God's
Wall.

* * * * *

With a similar fertility of illustration, Herschel sets before us the
phenomena of volcanic eruptions and their extraordinary effects.

In a district of Mexico, between the two streams of the Cin