ite difference between the aqueous and
igneous theories; for, we shall find it impossible to explain by the one
certain operations which must have necessarily required the great agent
generally employed in the other.

The subject of this chapter is a touch-stone for every theory of the
earth. In every quarter of this globe, perhaps in every extensive
country, bituminous strata are to be found; they are alternated with
those which are called aquiform, or which had been evidently formed by
subsidence of certain moved materials at the bottom of the sea; so far,
therefore, all those strata have had the same origin. In this point
I think I may assert, that all the different theories at present are
agreed; and it is only concerning certain transformations of those
strata, since their original collection, that have been ascribed to
different causes.

Of these transformations, which the strata must have undergone, there
are two kinds; one in relation to change of place and position; the
other in relation to solidity or consistence. It is only the last of
those two changes which is here to be the subject of consideration;
because, with regard to the first, there is nothing peculiar in these
bituminous strata to throw any light, in that respect, upon the others.
This is not the case with regard to the transformation in their chemical
character and consistence; bituminous bodies may not be affected by
chemical agents, such as fire and water, in the same manner as the
argillaceous, siliceous, micaceous, and such other strata that are
alternated with the bituminous; and thus we may find the means for
investigating the nature of that agent by which those strata in general
have been transformed in their substance; or we may find means for the
detecting of false theories which may have been formed with regard
to those operations in which the original deposits of water had been
changed.

We have had but two theories, with regard to the transformation of
those bodies which have had a known origin, or to the change of their
substance and consistence; the one of these which I have given is that
of heat or fusion; the other, which I wish to be compared with mine,
is that of water and infiltration. It is by this last that all authors
hitherto, in one shape or another, have endeavoured to explain the
changes that those strata must have undergone since the time of their
first formation at the bottom of the sea. They indiscriminately apply