ered to the seas more earth
material than has been carried into those basins by the great rivers.
If we could take account of all the volcanic ejections which have
occurred in this time, we should doubtless find that the sum of the
materials thus cast forth into the oceans was several times as great
as that which was delivered from the lands by all the superficial
agents which wear them away. Moreover, while the material from the
land, except the small part which is in a state of complete solution,
all falls close to the shore, the volcanic waste, because of its fine
division or because of the blebs of air which its masses contain, may
float for many years before it finds its way to the bottom, it may be
at the antipodes of the point at which it came from the earth. While
thus journeying through the sea the rock matter from the volcanoes is
apt to become dissolved in water; it is, indeed, doubtful if any
considerable part of that which enters the ocean goes by gravitation
to its floor. The greater portion probably enters the state of
solution and makes its way thence through the bodies of plants and
animals again into the ponderable state.

If an observer could view the earth from the surface of the moon, he
would probably each day behold one of these storms which the volcanoes
send forth. In the fortnight of darkness, even with the naked eye, it
would probably be possible to discern at any time several eruptions,
some of which would indicate that the earth's surface was ravaged by
great catastrophes. The nearer view of these actions shows us that
although locally and in small measure they are harmful to the life of
the earth, they are in a large way beneficent.

CHAPTER VIII.

THE SOIL.

The frequent mention which it has been necessary to make of soil
phenomena in the preceding chapters shows how intimately this feature
in the structure of the earth is blended with all the elements of its
physical history. It is now necessary for us to take up the phenomena
of soils in a consecutive manner.

The study of any considerable river basin enables us to trace the more
important steps which lead to the destructure and renovation of the
earth's detrital coating. In such an interpretation we note that
everywhere the rocks which were built on the sea bottom, and more or
less made over in the great laboratory of the earth's interior, are at
the surface, when exp