THE ROMANCE OF OUR TREES 



ancient flora of Europe was similar to that now flour- 

 ishing in the Far East. I do not mean that they were 

 specifically identical but that the generic types were 

 similar. If we picture to ourselves the onward, in- 

 evitable creeping southward of the ice we can easily 

 understand how trees and other forms of vegetation 

 were destroyed in its path, and only those which were 

 able to reach places of sufficient warmth to maintain 

 life survived. The greater the land extension toward 

 the south the greater chances had the vegetation, and 

 where the country was broken by mountain ranges 

 advantageous regions were more easily found. 



The ice on its path ground off the tops of moun- 

 tains and scoured out valleys to a great depth, and 

 when it retreated the face of much of the Northern 

 Hemisphere was changed. It disappeared from sea- 

 level valleys earlier than from mountain ranges and 

 so isolated groups of vegetation. If we picture this, 

 and remember that before the period of great cold set 

 in the vegetation of the North was everywhere very 

 similar, we can understand how to-day are found here 

 and there groups of trees isolated by thousands of 

 miles from their kindred. This explains the sepa- 

 ration of the Cedars of Lebanon, of the Taurus, of 

 Cyprus, of the Atlas Mountains and of the western Him- 

 alayas; also the isolation of the Nettle-trees, Honey- 

 locusts, Sweet-gums, Walnuts, and others in the 

 20 



