192 A. Gray—Forest Geography and Archeology. 
England and Virginia, and of California, clothed the land. We 
infer the climate from the trees; and the trees give sure indi- 
cations of the climate. 
I had divined and published the explanation long before I 
knew of the fossil plants. These, since made known, render the 
inference sure, and give us a clear idea of just what the climate 
ginia now. It would take too much time to enumerate the 
sorts of trees that have been identified by their leaves and 
fruits in the arctic later Tertiary deposits. 
I can only say, at large, that the same species have been 
found all round the world; that the richest and most extensive 
now peculiar 
to Japan and China, three kinds of Gingko-trees, for instance, 
persed over such widely separated continents. The lands all 
pas 8 from a polar center, and their proximate portions—how- 
climate, the forest they possess now, or rather the ancestors of it. 
During this long (and we may believe first) occupancy of Europe 
and the United States, were deposited in pools and shallow 
