The Shoshone Island.. 77 



the conviction that they are the product of a 

 moist, as well as a warm, atmosphere. One 

 readily sees from other than the evidence of 

 its fossil leaves why this must have been the 

 character of its climate, for in the early Ter- 

 tiary times the Cascade ridge of hills had not 

 yet reached an altitude sufficient to exclude 

 the warm, moist air of the Pacific ocean from 

 the island of Shoshone, as the present Cascade 

 range does now in that same region. So in 

 thosa clays the warm, moist atmosphere of 

 the Pacific ocean wrapped the island in its 

 cloudy folds and shed upon its slopes frequent 

 and refreshing rains. 



But more than this; much of the present 

 region of Alaska remained under the ocean 

 during the early Tertiary times, and thus pre- 

 sented an open passage for the Japan current 

 flowing north of these Oregon islands on its 

 way towards Hudson bay and the coast of 

 Greenland; this cut off all accumulations of 

 snow and ice between Oregon and the Arctic 

 ocean. 



