in that consolidation may have been effected either through
the concretion of substances dissolved in water or through fusion by
fire. Consolidation through the concretion of substances dissolved in
the sea is unlikely, for, in the first place, there are strata, such as
siliceous matter, which are insoluble, and which could not therefore
have been in solution; and, in the second place, the appearance of the
strata is contrary to this supposition. Consolidation was probably
effected by heat and fusion. All the substances in the earth may be
rendered fluid by heat, and all the appearances in the earth's crust are
consistent with the consolidation and crystallisation of fused
substances. Not only so, but we find rents and separations and veins in
the strata, such as would naturally occur in strata consolidated by the
cooling of fused masses, and other phenomena pointing to fusion by heat.
We may conclude, then, that all the solid strata of the globe have been
hardened from a state of fusion.

But how were these strata raised up from the bottom of the sea and
transformed into dry land? Even as heat was the consolidating power, so
heat was also probably the elevating power. The power of heat for the
expansion of bodies is, as we know, unlimited, and the expansive power
of heat was certainly competent to raise the strata above the sea. Heat
was certainly competent, and if we examine the crust of the earth we
find evidence that heat was used.

If the strata cemented by the heat of fusion were created by the
expansive power of heat acting from below, we should expect to find
every species of fracture, dislocation, and contortion in those bodies,
and every degree of departure from a horizontal towards a vertical
position. And this is just what we do find. From horizontal, the strata
are frequently found vertical; from continuous, broken, and separated in
every possible direction; and from a plane, bent and doubled. The theory
is confirmed by an examination of the veins and fissures of the earth
which contain matter foreign to the strata they traverse, and evidently
forced into them as a fluid under great pressure. Active volcanoes, and
extinct volcanoes, and the marks everywhere of volcanic action likewise
support the theory of expansion and elevation by heat. A volcano is not
made on purpose to frighten superstitious people into fits of piety and
devotion; it is to be considered as a spiracle of a subterranean
furnace.

Such