LATER GEOLOGICAL HISTORY OF NORTH AMERICA 19 



which subsequently became climatically segregated as the climates 

 became less uniform. 



At the time of which we are writing the sheep-berry and camphor 

 tree, the willow and alligator pear, the oak and Sterculia (a tropical 

 genus), the tulip- tree and the fig, the walnut and the palm, and 

 many other types which we now regard as essentially tropical on 

 the one hand or temperate on the other, flourished side by side. 

 A somewhat analogous grouping of temperate and tropical forms 

 occurs in certain modern forest such as those of southern Japan, 

 New Zealand, southern Chile, etc., where warmer temperate areas 

 by reason of the water vapor in the air and the heavy rainfall, 

 have a more uniform climate than is normal to their latitude and 

 support a vegetation of mixed types much like that of Upper 

 Cretaceous times. 



Some of the forms of the Rocky Mountain area Cretaceous flora 

 such as the magnolia, sassafras, fig, persimmon and tulip-tree still 

 flourish in other parts of the American continent, while others such 

 as Araucaria, Dammara, and various Proteaceae and Myrtaceae 

 once abundant throughout the Northern Hemisphere, became, with 

 the lapse of time, gradually extinct except in certain isolated areas 

 in the Southern Hemisphere. Many of these Cretaceous genera 

 were more diversified than they are in the modern flora. Thus 

 there were over ten species each of magnoKa, sassafras and tulip- 

 tree in this region at that time. Sequoia was also an abundant 

 element throughout the Cretaceous and the greater part of the 

 Tertiary period. Cretaceous fan palms, sometimes beautifuUy 

 preserved, have been found in Wyoming, Colorado, Vancouver, 

 New Jersey, Maryland, and elsewhere. 



The fortunate discovery of extensive beds of fossil plants of this 

 age along the west coast of Greenland in latitude 71° shows that 

 much the same assemblage of plants grew in the far North at that 

 time as are found in beds of this age along our Atlantic coast 

 from Martha's Vineyard to Texas, and there are many additional 

 facts pointing to the conclusion that there were no chmatic or 

 marine barriers between northeastern North America and Europe 

 nor between northwestern North America and Asia. This leaves 



