centuries which have elapsed since hunters or permanent
occupants first entered this region, many superficial changes have
taken place, not only about the entrances but within the caverns as
well. Very probably these alterations have converted caves once
occupied into places which at present are quite unfit for such
purposes. Talus has accumulated in front of the openings or partially
filled the front chambers; it may well be the case that this conceals
much refuse. Caves which, from similar deposits, are now difficult to
enter and dark to the doorway, may have been open and convenient.
Furthermore, caves with wet or muddy bottoms may owe such condition to
causes which have recently come into operation; or if they always
contained more or less water, the primitive dwellers could in many
cases have overcome such disadvantages by digging drains which have
since become choked and obliterated. Very small cavities, such as deep
rock-shelters; or caverns with a great thickness of earth on the
floors, now showing no trace of remains; or those with entrances so
small that it is necessary to crawl through--any of these, if cleared
out to the bottoms, might disclose material dating back to very early
times.

It might seem that the air in a cave constantly occupied would grow
stale and close; while smoke from the fires would in time become
annoying. But Indians used for fuel only dry wood and bark, the smoke
from which would be a negligible factor. The varying pressure of the
atmosphere outside creates a current of air in or out which is usually
imperceptible but which penetrates to the deepest recesses and insures
ventilation.

In view of the very primitive conditions under which cave dwellers
lived, as denoted by the artificial objects which they left, and the
low mentality indicated by the skulls, Mr. W.H. Holmes suggests that a
careful and extended study of these abodes may disclose a culture
lower than that prevailing among out-door dwellers in the same
localities. As no effort would be required to secure warmth and
shelter, and as food was abundant and easily procured, the people may
never have advanced from savagery, or may have retrograded.

None of these possibilities are taken into account when reporting upon
the caves described in the following pages; the information offered is
based entirely upon the present appearance of the places mentioned. To
attempt more would be merely offering guesses.

If "Cave Man"--usin