74 The Shoshone Island. 



Camp Watson, another farther west on the 

 upper waters of Bridge creek the marine 

 shells from all these localities being abund- 

 ant, very fine and all Cretaceous. 



Mention was made of back-lying ridges of 

 the older rocks that escaped the violent 

 changes of the early history of both islands. 



A good example of this may be seen on 

 an elevated ridge west of Canyon City, the 

 Jurassic rocks of which are plainly seen with 

 their characteristic fossils unchanged. 



But. the grand work of building at this 

 time was Cretaceous work, and the island of 

 Shoshone went on enlarging its outline in 

 times of elevation of surface and lessening its 

 area in times of subsidence throughout the 

 whole period of Cretaceous times. The geo- 

 graphical change that followed the elevation 

 of the Cascade range has already been men- 

 tioned in its relation to both islands. A word 

 on its relations to the Shoshone island. 



In neither case was the dominance of the 

 island feature lost. As soon as this great sea 

 dyke reached the surface of the ocean it sep- 



