Hence, in those two different operations, of forming mineral
veins, and erecting strata from a lower to a higher place, the principle
is the same; for, neither can be done without violent fracture and
dislocation.
We now only want to know, how far it is by the same power, as well as
upon the same principle, that these two operations have been made.
An expansive force, acting from below, is the power most proper for
erecting masses; but whether it is a power of the same nature with that
which has been employed in forming mineral veins, will best appear in
knowing the nature of their contents. These, therefore, may be now
considered.
Every species of fracture, and every degree of dislocation and
contortion, may be perceived in the form of mineral veins; and there is
no other general principle to be observed in examining their form. But,
in examining their contents, some other principle may appear, so far as,
to the dislocating power or force, there may be superadded matter, by
which something in relation to the nature of the power may be known.
If, for example, a tree or a rock shall be found simply split asunder,
although there be no doubt with regard to some power having been applied
in order to produce the effect, yet we are left merely to conjecture at
the power.
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