The Siskiyou Island. 45 



brief consideration of the apparent causes 

 that underlie these surface movements may 

 not be out of place. 



The first of the series within the range of 

 our subject was that which built up the Rocky 

 mountains; the second that which -forced up 

 the Cascade mountains; the third, this latest 

 one, the elevation of the Coast range. 



In all these movements the work was be- 

 gun in the crumpling up of the bed of the 

 sea. In proof of this, one has only to point 

 out the fact common to all three regions, that 

 the sea mud, now hardened into rock and ele- 

 vated to the shoulders of these mountains and 

 constituting the bulk of the mountain mass, 

 abounds in sea shells, many of which lie ap- 

 parently undisturbed in the very mud banks 

 in which they lived. Another fact common to 

 all three regions, is the evidence they furnish 

 of the great force and heat that accompanied 

 their elevation. This is seen in such portions 

 of the masses as offered most resistance to this 

 elevating force, changing in such places, as 

 by fire, the very structure of the mass. 



