The Siskiyou Island. 49 



This latest of these continental upfolds, the 

 Coast range, having taken its place among 

 world facts, an outline of its geological rela- 

 tions will be important. 



At the opening of the Miocene period the 

 coast upfold was only a line of islands, the 

 geological materials of which were the re- 

 cently elevated belts of Eocene. Between 

 these islands were open passages through 

 which ebbed and flowed the ocean tides, while 

 the enclosed belt of water between the isl- 

 ands and the Cascade range was wide and 

 deep, a body of water similar to Queen Char- 

 lotte's sound of to-day. It was on the inner 

 slopes of this sound that the marine waters 

 of the period deposited their rich and varied 

 record of the life of the times. 



In this way the outline of our modern 

 Willamette valley was first blocked out, the 

 framework of which still remains. Its rim 

 has varied in altitude, its bed has varied in 

 depth, but its original outline abides. 



Its latest western border, the Coast range 

 of mountains, was not entire in the period we 



