their final appearance on the
_fourth_ day of creation. Little more than half a century has yet passed
since geologic science was sufficiently developed to influence the
interpretation given of the three _other_ days' work. And respecting the
work of at least the first and second days, more especially that of the
second, we can still but vaguely guess. The science necessary to the
right understanding of these portions of the prophetic record has still,
it would seem, to be developed, if, indeed, it be destined at all to
exist; and at present we can indulge in but doubtful surmises regarding
them. What may be termed the three _geologic_ days,--the third, fifth,
and sixth,--may be held to have extended over those Carboniferous
periods during which the great plants were created,--over those Oolitic
and Cretacious periods during which the great sea monsters and birds
were created,--and over those Tertiary periods during which the great
terrestrial mammals were created. For the intervening or fourth day we
have that wide space represented by the Permian and Triassic periods,
which, less conspicuous in their floras than the period that went
immediately before, and less conspicuous in their faunas than the
periods that came immediately after, were marked by the decline, and
ultimate extinction, of the Palaeozoic forms, and the first partially
developed beginnings of the Secondary ones. And for the first and second
days there remain the great Azoic period, during which the immensely
developed gneisses, mica schists, and primary clay slates, were
deposited, and the two extended periods represented by the Silurian and
Old Red Sandstone systems. These, taken together, exhaust the geologic
scale, and may be named in their order as, _first_, the Azoic day or
period; _second_, the Silurian and Old Red Sandstone day or period;
_third_, the Carboniferous day or period; _fourth_, the Permian and
Triassic day or period; _fifth_, the Oolitic and Cretaceous day or
period; and _sixth_, the Tertiary day or period. Let us attempt
conceiving how they might have appeared pictorially, if revealed in a
series of visions to Moses, as the successive scenes of a great
air-drawn panorama.

During the Azoic period, ere life appears to have begun on our planet,
the temperature of the earth's crust seems to have been so high, that
the strata, at first deposited apparently in water, passed into a
semi-fluid state, became strangely waved and contorted, a