A, Gray—Forest Geography and Archeology. 195 
trast, we find the land unbroken and open down to the tropic, 
and the mountains running north and south. The trees, when 
touched on the north by the on-coming refrigeration, had only 
to move their southern border southward, along an open way, 
as far as the exigency required; and there was no impediment 
to their due return. Then the more southern latitude of the 
United States gave great advantage over . On th 
Atlantic border, proper glaciation was felt only in the northern 
part, down to about latitude 40°. In the interior of the country, 
owing doubtless to greater dryness and summer heat, the limit 
receded greatly northward in the Mississippi Valley, and gave 
only local glaciers to the Rocky Mountains; and no volcanic 
outbreaks or violent changes of any kind have here occurred 
since the types of our present vegetation came to the land. 
our lines have been cast in pleasant places, and the goodly 
heritage of forest trees is one of the consequences. 
The still greater richness of Northeast Asia in arboreal vege- 
tation may find explanation in the prevalence of particularly 
favorable conditions, both ante-glacial and recent. trees 
of the Miocene cireumpolar forest appear to have found therea 
Secure home; and the Japanese islands, to which most of these 
trees belong, must be remarkably adapted to them. The situa- 
tion of these islands—analogous to that of Great Britain, but 
with the advantage of lower latitude and greater sunshine— 
heir ample extent north and south, their diversified configura- 
tion, their proximity to the great Pacific gulf-stream, by which a 
vast body of warm water sweeps along their accentuated shores, 
and the comparatively equable diffusion of rain throughout the 
year, all probably conspire to the preservation and develop- 
ment of an originally ample inheritance. 
The case of the Pacific forest is remarkable and paradoxical. 
It is, as we know, the sole refuge of the most characteristic and 
—— type of Miocene Conifers, the Sequoias; it is rich 
im coniferous types beyond any country except Japan; in its 
gold-bearing gravels are indications that it possessed, seemingly 
