THE FORESTS 189 



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 f What are its 

 relations to climate, soil, and associated trees f 



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 



