THE ROMANCE OF OUR TREES 



fairly certain that during this epoch the tree flourished 

 in the Southern Hemisphere. In the strata of the 

 next era — the Jurassic or Reptile Age — the Ginkgo is 

 abundantly present in America, Asia, and Europe. 

 From rocks of this age in Canada, China, Japan, north- 

 ern Germany, and England northward to Greenland, 

 Siberia, and Franz-Joseph-Land many fossil species 

 have been described. In some of them the leaves 

 are quite indistinguishable from those of the existing 

 species. From the rocks of the Chalk Age (Cretace- 

 ous) of North America, Greenland, and Vancouver 

 Island, fossil species have been named which are prob- 

 ably identical with . that living to-day. From the 

 Tertiary period, fossils of several species have been 

 described from widely separated parts of the Northern 

 Hemisphere, and it may be concluded with approxi- 

 mate certainty that the living Ginkgo biloba flourished 

 at that period ; also that it was a common tree in the 

 present temperate and circumpolar regions of the 

 v/hole Northern Hemisphere. 



The close of the Tertiary period was marked by a 

 glacial epoch which, in Europe and North America 

 in particular, destroyed much of the vegetation. 

 In eastern North America the ice-cap extended as 

 far south as Philadelphia (Lat. 40° N.) as the scarred 

 rocks, erratic boulders, and detritus amply testify. 

 This ice-cap did not reach any part of China, Korea, 



50 



