---------------------+----------
| _Archean_ | |No fossils found, but |
| | |life inferred from the |
| | |existence of iron ores |
ARCHEOZOIC | |and limestones, which |
| | |are generally formed in|
| | |the presence of |
| | |organisms. |
---------+---------------+--------------+-----------------------+----------

Who can safely declare that the day will not come when a new
Yellowstone, hurled from reopened volcanoes, shall found itself upon the
buried ruin of the present Yellowstone; when the present Sierra shall
have disappeared into the Pacific and the deserts of the Great Basin
become the gardens of the hemisphere; when a new Rocky Mountain system
shall have grown upon the eroded and dissipated granites of the present;
when shallow seas shall join anew Hudson Bay with the Gulf of Mexico;
when a new and lofty Appalachian Range shall replace the rounded summits
of to-day; when a race of beings as superior to man, intellectually and
spiritually, as man is superior to the ape, shall endeavor to
reconstruct a picture of man from the occasional remnants which floods may
wash into view?

NOTE EXPLANATORY OF THE ESTIMATE OF GEOLOGIC TIME IN THE TABLE ON
THE OPPOSITE PAGE

The general assumption of modern geologists is that a hundred
million years have elapsed since the close of the Archean period;
at least this is a round number, convenient for thinking and
discussion. The recent tendency has been greatly to increase
conceptions of geologic time over the highly conservative estimates
of a few years ago, and a strong disposition is shown to regard the
Algonkian period as one of very great length, extremists even
suggesting that it may have equalled all time since. For the
purposes of this popular book, then, let us conceive that the earth
has existed for a hundred million years since Archean times, and
that one-third of this was Algonkian; and let us apportion the
two-thirds remaining among succeeding eras in the average of the
proportions adopted by Professor Joseph Barrell of Yale University,
whose recent speculations upon geologic time have attracted wide
attention.

Fantastic, you