es of the earth, whether of
primitive masses or those of secondary formation, whether uniform and
homogeneous, or compound and mixed of those two different kinds of
bodies, the system is always the same, of hills and valleys, lakes and
rivers, ravines and streams: no man can say, by looking into the most
perfect map, what is primary or what secondary in the constitution of
the globe. It is the same system of larger rivers branching into lesser
and lesser in a continued series, of smaller rivers in like manner
branching into rivulets, and of rivulets terminating at last into
springs or temporary streams. The principle is universal; and, having
learned the natural history of one river, we know the constitution of
every other upon the face of the earth.

Thus all the surface of this earth is formed according to a regular
system of heights and hollows, hills and valleys, rivulets and rivers,
and these rivers return the waters of the atmosphere into the general
mass, in like manner as the blood, returning to the heart, is conducted
in the veins. But as the solid land, formed at the bottom of the sea or
in the bowels of the earth, could not be there constructed according to
that system of things which we find so widely pursued upon the surface
of the globe, it must be by wasting the solid parts of the land that
this system of the surface has been formed, in like manner as it is by
the operations of the sea that the shape of the land is determined, upon
the shore.

Thus it has been shown, that the general tendency of the operations
natural to the surface of the globe is to wear the surface of the earth,
and waste the land; consequently that, however long the continents of
this earth may be supposed to last, they are on the whole in a constant
state of diminution and decay; and, in the progress of time, will
naturally disappear. Hence confirmation is added to that mineral system
of the earth, by which the present land is supposed to have acquired
solidity and hardness; and according to which future land is supposed to
be preparing from the materials of the sea and former continents; which
land will be brought to light in time, to supply the place of that which
necessarily wastes, in serving plants and animals. But what is here more
particularly to the purpose is this; that we find an explanation of that
various shape and conformation which is to be observed upon the surface
of this earth, as being the effect of causes which ar