r, and
which shows the use as well as means for the formation of our mountains.
Here illustration and confirmation of the theory may be found in
the examination of nature; and natural appearances may receive that
explanation which the generalization of a proper theory affords.

The particular forms of mountains depend upon the compound operation
of two very different causes. One of these consists in those mineral
operations by which the strata of the earth are consolidated and
displaced, or disordered in the production of land above the sea; the
other again consists in those meteorological operations by which this
earth is rendered a habitable world. In the one operation, loose
materials are united, for the purpose of resisting the dissolving powers
which act upon the surface of the earth; in the other, consolidated
masses are again dissolved, for the purpose of serving vegetation
and entertaining animal life. But, in fulfilling those purposes of a
habitable earth, or serving that great end, the land above the level of
the sea is wasted, and the materials are transported to the bottom of
the ocean from whence that consolidated land had come. At present we
only want to see the cause of those particular shapes which are found
among the most elevated places of our earth, those places upon which the
wasting powers of the surface act with greatest energy or force.

In explaining those appearances of degraded mountains variously
shaped, the fact we are now to reason upon is this; first, that in the
consolidated earth we find great inequality in the resisting powers of
the various consolidated bodies, both from the different degrees of
consolidation which had taken place among them, and the different
degrees of solubility which is found in the consolidated substances;
and, secondly, that we find great diversity in the size, form, and
positions of those most durable bodies which, by resisting longer the
effects of the wearing operations of the surface, must determine the
shape of the remaining mass. Now so far as every particular shape upon
the surface of this earth is found to correspond to the effect of those
two causes, the theory which gave those principles must be confirmed in
the examination of the earth; and so far as the theory is admitted to be
just, we have principles for the explanation of every appearance of that
kind, whether from the forming or destroying operations of this earth,
there being no part upon the sur