re, we must conclude that
it was at the bottom of the ocean those stratified bodies had been
consolidated.]

To conclude this long chemico-mineral disquisition, I have specimens in
which the mixture of calcareous, siliceous, and metallic substances,
in almost every species of concretion which is to be found in mineral
bodies, may be observed, and in which there is exhibited, in miniature,
almost every species of mineral transaction, which, in nature, is found
upon a scale of grandeur and magnificence. They are nodules contained in
the whin-stone, porphyry, or basaltes of the Calton-hill, by Edinburgh;
a body which is to be afterwards examined, when it will be found to have
flowed, and to have been in fusion, by the operation of subterraneous
heat.

This evidence, though most conclusive with regard to the application of
subterraneous heat, as the means employed in bringing into fusion all
the different substances with which strata may be found consolidated, is
not directly a proof that strata had been consolidated by the fusion of
their proper substance. It was necessary to see the general nature of
the evidence, for the universal application of subterraneous heat, in
the fusion of every kind of mineral body. Now, that this has been done,
we may give examples of strata consolidated without the introduction
of foreign matter, merely by the softening or fusion of their own
materials.

For this purpose, we may consider two different species of strata,
such as are perfectly simple in their nature, of the most distinct
substances, and whose origin is perfectly understood, consequently,
whose subsequent changes may be reasoned upon with certainty and
clearness. These are the siliceous and calcareous strata; and these
are the two prevailing substances of the globe, all the rest being, in
comparison of these, as nothing; for unless it be the bituminous or coal
strata, there is hardly any other which does not necessarily contain
more or less of one or other of these two substances. If, therefore,
it can be shown, that both of those two general strata have been
consolidated by the simple fusion of their substance, no _desideratum_
or doubt will remain, with regard to the nature of that operation which
has been transacted at great depths of the earth, places to which all
access is denied to mortal eyes.

We are now to prove, _first_, That those strata have been consolidated
by simple fusion; and, _2dly_, That this operation is