forms, and also of shattering and upheaving parts of the earth-crust.

For there can be no doubt that fiery heat does exist as a mighty power
within our earth, though to what extent we are not able to say.

These two fellow-workers in nature have different modes of working.
One we can see on all sides, quietly progressing, demolishing land
patiently bit by bit, building up land steadily grain by grain. The
other, though more commonly hidden from sight, is fierce and
tumultuous in character, and shows his power in occasional terrific
outbursts.

We can scarcely realize what the power is of the imprisoned fiery
forces underground, though even we are not without some witness of
their existence. From time to time even our firm land has been felt to
tremble with a thrill from some far-off shock; and even in our country
is seen the marvel of scalding water pouring unceasingly from deep
underground....

Think of the tremendous eruptions of Vesuvius, of Etna, of Hecla, of
Mauna Loa. Think of whole towns crushed and buried, with their
thousands of living inhabitants. Think of rivers of glowing lava
streaming up from regions below ground, and pouring along the surface
for a distance of forty, fifty, and even sixty miles, as in Iceland
and Hawaii. Think of red-hot cinders flung from a volcano-crater to a
height of ten thousand feet. Think of lakes of liquid fire in other
craters, five hundred to a thousand feet across, huge cauldrons of
boiling rock. Think of showers of ashes from the furnace below of yet
another, borne so high aloft as to be carried seven hundred miles
before they sank to earth again. Think of millions of red-hot stones