An Expository Outline of the Vestiges of the Natural History of Creation | Page 9

great
inferior crystalline mass. This rocky matter must have been in a state of
fusion from heat at the time of its projection, for it is often found to
have run into and filled up lateral chinks in these rents. There are even
instances where it has been rent again, and a newer melted matter of the
same character sent through the opening. Finally, in the crust as thus
arranged, there are, in many places, chinks containing veins of metal.
Thus, there is first a great inferior mass, composed of crystalline rock,
and probably resting immediately on the fused and expanded matter of
the interior: next, layers or strata of aqueous origin; next, irregular
masses of melted inferior rock that have been sent up volcanically and
confusedly at various times amongst the aqueous rocks, breaking up
these into masses, and tossing them out of their original levels."
This, we believe, is a correct outline of the crust of the earth, so far as it
has been possible to observe it. It exhibits extraordinary signs of
commotion and vicissitude; the lowest rocks indicating a previous
condition of igneous fusion; those above them of aqueous solution. Fire
and water have thus been the chief tellurian anarchists, and the shaking
of continents and the constant shifting of level in sea and land still
continue to attest their restless energies. That igneous matter has,
during many periods, been protruded from below--that mountains have
risen in succession from the sea, and injected their molten substance
through cracks and fissures of superincumbent strata--are facts resting
on indubitable evidence. Many masses of granite became the solid
bottom of some portions of the sea before the secondary strata were
laid gradually upon them. The granite of Mont Blanc rose during a
recent tertiary period. "We can prove," says Professor SEDGWICK,
"more than mere shiftings of level, and that many portions of sea and
land have entirely changed their places. The rocks at the top of
Snowdon are full of petrified sea-shells; the same may be said of some
high crests of the Alps, Pyrenees, and Andes. We have proof
demonstrative that many parts of Scotland, and that all England,
formed, during many ages, the solid bottom of the sea. It may be true
that the antagonist powers of nature during the human period have

reached a kind of balance. But during all geological periods there have
been such long intervals of repose, or of such gradual movements, that
we may trace the history of the earth in the successive deposits formed
in the waters of the sea." This is the great business of geology.
Although at first sight the interior of the earth appears a confused scene,
after careful observation we readily detect in it a regularity and order
from which much instructive light is thrown on its past vicissitudes.
The deposition of the aqueous rocks and the projection of the volcanic
have unquestionably taken place since the settlement of the earth in its
present form. They are, indeed, of an order of events which are going
on under the agency of intelligible causes, down to the present day. We
may therefore consider these generally as recent transactions. But
advancing to the far distant antecedent era of its existence, we may
consider it to have been a globe of its present size enveloped in the
crystalline rock already described, with the waters of the present seas
and the present atmosphere around it, though these were probably in
considerably different conditions, both as to temperature and their
constituent materials, from what they now are. We may thus presume
that, without this primitive case of granitic texture, the great bulk of the
matters of our earth were agglomerated, whether in a fluid or solid state
is uncertain; but there cannot be any doubt that they continue to exist in
a condition of great heat and compression, having a mean density of
more than double that of the minerals on the surface.
Judging from the results and still observable conditions, it may be
inferred that the heat retained in the interior of the globe was more
intense, or had greater freedom to act, in some places than in others.
These become the scenes of volcanic operations, and in time marked
their situations by the extrusion from below of trap and basalts--rocks
composed of the crystalline matter, fused by intense heat, and
developed on the surface in various conditions, according to the
particular circumstances under which it was sent up; some, for example,
being thrown up under water, and some in the open air, which
contingencies would make considerable difference in its texture and
appearance. It would, however, be a mistake to infer that, previous to
these eruptions, the earth was a smooth ball, with air and water playing

round it. Geology tells us