y. I have examined cargoes of
this lime-stone brought to the west of Scotland, and find the most
perfect evidence of this body having been once a mass of chalk, which is
now a solid marble.

Thus, if it is by means of fusion that the strata of the earth have
been, in many places, consolidated, we must conclude, that all the
degrees of consolidation, which are indefinite, have been brought about
by the same means.

Now, that all the strata of the mineral regions, which are those only
now examined, have been consolidated in some degree, is a fact for which
no proof can be offered here, but must be submitted to experience and
inquiry; so far, however, as they shall be considered as consolidated in
any degree, which they certainly are in general, we have investigated
the means which had been employed in that mineral operation.

We have now considered the concretions of particular bodies, and the
general consolidation of strata; but it may be alleged, that there is
a great part of the solid mass of this earth not properly comprehended
among those bodies which have been thus proved to be consolidated by
means of fusion. The body here alluded to is granite; a mass which is
not generally stratified, and which, being a body perfectly solid,
and forming some part in the structure of this earth, deserves to be
considered.

The nature of granite, as a part of the structure of the earth, is too
intricate a subject to be here considered, where we only seek to prove
the fusion of a substance from the evident marks which are to be
observed in a body. We shall, therefore, only now consider one
particular species of granite; and if this shall appear to have been in
a fluid state of fusion, we may be allowed to extend this property to
all the kind.

The species now to be examined comes from the north country, about four
or five miles west from Portfoy, on the road to Huntly. I have not been
upon the spot, but am informed that this rock is immediately connected
or continuous with the common granite of the country. This indeed
appears in the specimens which I have got; for, in some of these, there
is to be perceived a gradation from the regular to the irregular sort.

This rock may indeed be considered, in some respects, as a porphyry; for
it has an evident ground, which is feld-spar, in its sparry state;
and it is, in one view, distinctly maculated with quartz, which is
transparent, but somewhat dark-coloured[11].

[Note 11: Plate