212 THE GENESIS AND MIGRATIONS OF PLANTS 



the European chalk, and containing similar microscopic organ- 

 isms. This extends far north into the British territory, 1 indi- 

 cating farther subsidence and the prevalence of a vast Mediter- 

 ranean Sea, filled with warm water from the equatorial cur- 

 rents, and not invaded by cold waters from the north. This 

 is succeeded by Upper Cretaceous deposits of clay and sand- 

 stone, with marine remains, though very sparsely distributed ; 

 and these show that further subsidence or denudation in the 

 north had opened a way for the arctic currents, producing a 

 fall of temperature at the close of the Cretaceous, and partially 

 filling up the Mediterranean of that period. 



Of the flora of the Middle and Upper Cretaceous periods, 

 which must have been very long, we know something in the 

 interior regions through the plants of Dunvegan and Peace 

 River ; 2 and on the coast of British Columbia we have the 

 remarkable Cretaceous coalfield of Vancouver's Island, which 

 holds the remains of plants of modern genera, including species 

 of fan palm, ginkgo, evergreen oak, tulip tree, and other forms 

 proper to a warm temperature or subtropical climate. They 

 probably indicate a warmer climate as then prevalent on the 

 Pacific coast than in the interior, and in this respect corre- 

 spond with a meagre transition flora, intermediate between the 

 Cretaceous and Eocene or earliest Tertiary of the interior re- 

 gions, and named by Lesquereux the Lower Lignitic. 



Immediately above these Upper Cretaceous beds we have 

 the great Lignite Tertiary of the west the Laramie group of 

 recent American reports 3 abounding in fossil plants, proper 

 to a temperate climate, at one time regarded as Miocene, but 

 now known to be Lower Eocene. 4 These beds, with their 



1 G. M. Dawson, Report on Forty-ninth Parallel. 



* Trans. Royal Society of Canada. 



8 Ward, Repts. and Bulletins Am. Geol. Survey. 



4 Lesquereux's Tertiary Flora ; White and Ward on the Laramie Group; 

 Stevenson, Geological Relations of Lignitic Groups, Am. Phil. Soc.,June, 

 1875- 



