ions formed in the bosom of the earth by its generative powers;
for a scrupulous comparison of the remains shows not the slightest
difference between the fossil shells and those that are now found in the
ocean. It is clear, then, that they inhabited the sea, and that they
were deposited by the sea in the places where they are now found; and it
follows, too, that the sea rested in these places long enough to form
regular, dense, vast deposits of aquatic animals.

The bed of the sea, accordingly, must have undergone some change either
in extent or situation.

Further, we find under the horizontal strata, _inclined_ strata. Thus
the sea, previously to the formation of the horizontal strata, must have
formed others, which have been broken, inclined, and overturned by some
unknown causes.

More than this, we find that the fossils vary with the depth of the
strata, and that the fossils of the deeper and more ancient strata
exhibit a formation proper to themselves; and we find in some of the
strata, too, remains of terrestrial life.

The evidence is thus plain that the animal life in the sea has varied,
and that parts of the earth's surface have been alternately dry land and
ocean. The very soil, which terrestrial animals at present inhabit has a
history of previous animal life, and then submersion under the sea.

The reiterated irruptions and retreats of the sea have not all been
gradual, but, on the contrary, they have been produced by sudden
catastrophes. The last catastrophe, which inundated and again left dry
our present continents, left in the northern countries the carcasses of
large quadrupeds, which were frozen, and which are preserved even to the
present day, with their skin, hair and flesh. Had they not been frozen
the moment they were killed, they must have putrefied; and, on the other
hand, the intense frost could not have been the ordinary climatic
condition, for they could not have existed at such low temperatures. In
the same instant, then, in which these animals perished the climate
which they inhabited must have undergone a complete revolution.

The ruptures, the inclinations, the overturnings of the more ancient
strata, likewise point to sudden and violent changes.

Animal life, then, has been frequently disturbed on this earth by
terrific catastrophes. Living beings innumerable have perished. The
inhabitants of the dry land have been engulfed by deluges; and the
tenants of the water, deserted by thei