ave haunted the bays and waters of the primitive
lands. But in this state of things there was no order of events similar
to the present; the crust of the globe was exceedingly slender, and the
source of fire a small distance from the surface. In consequence of
contraction in one part of the mass, cavities were opened, which caused
the entrance of water, and immense volcanic explosions took place,
raising one part of the surface, depressing another, producing mountains,
and causing new and extensive depositions from the primitive ocean.
Changes of this kind must have been extremely frequent in the early
epochas of nature, and the only living forms of which the remains are
found in the strata that are the monuments of these changes, are those of
plants, fishes, birds, and oviparous reptiles, which seem most fitted to
exist in such a war of the elements. When these revolutions became less
frequent, and the globe became still more cooled, and the inequalities of
its temperature preserved by the mountain chains, more perfect animals
became its inhabitants, many of which, such as the mammoth, megalonix,
megatherium, and gigantic hyena, are now extinct. At this period the
temperature of the ocean seems to have been not much higher than it is at
present, and the changes produced by occasional eruptions of it have left
no consolidated rocks. Yet one of these eruptions appears to have been
of great extent and some duration, and seems to have been the cause of
those immense quantities of water-worn stones, gravel and sand, which are
usually called diluvian remains; and it is probable that this effect was
connected with the elevation of a new continent in the southern
hemisphere by volcanic fire. When the system of things became so
permanent that the tremendous revolutions depending upon the destruction
of the equilibrium between the heating and cooling agencies were no
longer to be dreaded, the creation of man took place; and since that
period there has been little alteration in the physical circumstances of
our globe. Volcanoes sometimes occasion the rise of new islands,
portions of the old continent are constantly washed by rivers into the
sea; but these changes are too insignificant to affect the destinies of
man, or the nature of the physical circumstances of things. On the
hypothesis that I have adopted, however, it must be remembered that the
present surface of the globe is merely a thin crust surrounding a nucleus
of