ngs, thus demonstrating that
the remnant of the trunk that made the ditch has lain on the ground
_more_ than 380 years. For it is evident that to find the whole
time, we must add to the 380 years the time that the vanished portion of
the trunk lay in the ditch before being burned out of the way, plus the
time that passed before the seed from which the monumental fir sprang
fell into the prepared soil and took root. Now, because Sequoia trunks
are never wholly consumed in one forest fire, and those fires recur only
at considerable intervals, and because Sequoia ditches after being
cleared are often left unplanted for centuries, it becomes evident that
the trunk remnant in question may probably have lain a thousand years or
more. And this instance is by no means a rare one.

But admitting that upon those areas supposed to have been once covered
with Sequoia every tree may have fallen, and every trunk may have been
burned or buried, leaving not a remnant, many of the ditches made by the
fall of the ponderous trunks, and the bowls made by their upturning
roots, would remain patent for thousands of years after the last vestige
of the trunks that made them had vanished. Much of this ditch-writing
would no doubt be quickly effaced by the flood-action of overflowing
streams and rain-washing; but no inconsiderable portion would remain
enduringly engraved on ridge-tops beyond such destructive action; for,
where all the conditions are favorable, it is almost imperishable.
_Now these historic ditches and root bowls occur in all the present
Sequoia groves and forests, but as far as I have observed, not the
faintest vestige of one presents itself outside of them_.

We therefore conclude that the area covered by Sequoia has not been
diminished during the last eight or ten thousand years, and probably not
at all in post-glacial times.

_Is the species verging to extinction? What are its relations to
climate, soil, and associated trees?_

All the phenomena bearing on these questions also throw light, as we
shall endeavor to show, upon the peculiar distribution of the species,
and sustain the conclusion already arrived at on the question of
extension.

In the northern groups, as we have seen, there are few young trees or
saplings growing up around the failing old ones to perpetuate the race,
and in as much as those aged Sequoias, so nearly childless, are the only
ones commonly known, the species, to most observers, seems doomed to