200 THE CHAIN OF LIFE. 



America has arisen from the fact that the plants which are 

 Eocene in Greenland and America are Miocene in Europe. 

 The statement of this places the reader somewhat behind the 

 scenes, for the fact is .ot icnown to some who are regarded as 

 high authorities in this matter. In the Western States, the 

 Da'.vota group of Lesquereux is overlaid by 2000 feet of 

 Cretaceous beds, containing the marine shells characteristic of 

 that age, but no plants. But in Vancouver's Island these same 

 Upper Cretaceous beds contain an abundant flora, which 

 some botanists persist in calling Tertiary for reasons to 

 be mentioned in the sequel. Above the 2000 feet of marine 

 beds overlying the Dakota group is the Lower Lignite group of 

 Lesquereux, holding many fossil plants, including Palms and 

 other evidences of a warmer climate than that of the CretaceouL, 

 and which constitute a Lower Eocene flora correspondir ■' 

 some respects to that of Europe. This is succeeded by an 

 Upper Lignite group, also Eocene, but representing a more 

 temperate climate, and therefore resembling more nearly the 

 Cretaceous flora. This is nearly identical with the so-called 

 Miocene of Greenland, Alaska, and McKenzie River, which 

 the facts collected by the Canadian geologists have shown to 

 be really Eocene.^ But the Canadian reports containing 

 these facts are comparatively little known in Europe, hence 

 incorrect ideas as to the succession of these floras have been 

 handed from one writer to another. 



To those who adopt extreme views as to the refrigeration of 

 the northern hemisphere in so-called glacial times, there is 

 great difficulty in accounting for the continued existence of 

 the early Tertiary flora ; but if we adopt moderate views as 

 to this, and demand merely a great subsidence, with much 

 reduction of mean temperature, we may suppose that the 

 plants previously existing were preserved on insular spots, 

 whence they were ready to recolonise the land on its emergence 

 from the sea. It seems certain, however, that our continents 



1 G. M. Dawson, Report on \<^th Paralld ; Report on British Co'.iimbia. 



