as the evidence could be traced, there was nothing to contradict
the hypothesis. But when you look, not to the testimonial
evidence--which, considering the relative insignificance of the
antiquity of human records, might not be good for much in this
case--but to the circumstantial evidence, then you find that
this hypothesis is absolutely incompatible with such evidence as
we have; which is of so plain and so simple a character that it
is impossible in any way to escape from the conclusions which it
forces upon us.

You are, doubtless, all aware that the outer substance of the
earth, which alone is accessible to direct observation, is not
of a homogeneous character, but that it is made up of a number
of layers or strata, the titles of the principal groups of which
are placed upon the accompanying diagram. Each of these groups
represents a number of beds of sand, of stone, of clay, of
slate, and of various other materials.

On careful examination, it is found that the materials of which
each of these layers of more or less hard rock are composed are,
for the most part, of the same nature as those which are at
present being formed under known conditions on the surface of
the earth. For example, the chalk, which constitutes a great
part of the Cretaceous formation in some parts of the world, is
practically identical in its physical and chemical characters
with a substance which is now being formed at the bottom of the
Atlantic Ocean, and covers an enormous area; other beds of rock
are comparable with the sands which are being formed upon sea-
shores, packed together, and so on. Thus, omitting rocks of
igneous origin, it is demonstrable that all these beds of stone,