44 The Siskiyou Island. 



and later a range of hills, and still later a range 

 of mountains the Coast range of the future 

 Pacific coast. It will at once strike the reader 

 that this new event has in it several points of 

 likeness, both in itself and in its results, to 

 the elevation of the Cascade barrier already 

 described. 



This conclusion is entirely just, for both 

 of these upcrumplings became permanent 

 ranges of mountains; both cut off perma- 

 nently portions of the Pacific ocean, changing 

 these to inland belts of water, later to drain- 

 age troughs and ultimately into valleys; and 

 in each case one of our ancient islands be- 

 came the dominant feature of the region thus 

 added to the land, the region east of the Cas- 

 cade barrier dominated by the island of Sho- 

 shone, the region between the Cascade and 

 the Coast range dominated by the island of 

 Siskiyou. 



Inasmuch as the upfold along the coast 

 line is apparently the final one in the struc- 

 ture of North America, and as two others 

 of like structural character preceded this, a 



