The Two Islands. 27 



without melting them. Oregon's geological 

 history had its origin in just such a violent 

 crumpling of its ancient sea bed, and when the 

 disturbance that caused this ceased, and quiet 

 was restored to the region, there was left, as 

 a result, two islands off the western coast of 

 North America. 



It was these two islands that grew into 

 Oregon. 



Of these islands, one occupied the eastern 

 portion of what is now the Blue Mountain 

 region, the other extending over what is now 

 the southwest corner of the State of Oregon, 

 together with a portion of Northern Califor- 

 nia, occupying what is now the Siskiyou 

 Mountain region. 



The violence that caused the elevation of 

 these islands above the sea level was such 

 that the original sediments of which they 

 were composed were changed. If originally 

 beds of limestone, these, in the process of up- 

 heaval became marble; if originally clayey or 

 argillaceous, the change was into hardened 

 slate, and pasty masses of granite were forced 



