DRY LANDS AND FORESTS 101 



gigantic cataclysm of past geologic times 

 powerful enough to pile granite and quartz 

 three miles high in the air, raised the Rocky 

 Mountains as a wall on the west against the 

 passage of the moisture-laden winds of the 

 Pacific Ocean. The sudden cooling of the 

 humid air currents which have drunk their 

 fill in their race over the waves robs them of 

 their moisture as they rise high to ride over 

 the range of hills and mountains. In southern 

 California the razor-like peaks of the high 

 Sierras account for the almost tropical luxuri- 

 ance of vegetation on the windward slope of 

 the mountains and the barren desert sand to 

 the leeward; yet these two regions lie parallel 

 to each other and seem separated by little more 

 than a stone's throw. The Sierras crowd the 

 ocean closely on the south. To the north, 

 where the Cascade Range sets farther back 

 from the tide, a strip of well-watered fertile 

 country more than one hundred miles wide in 

 places extends northward through California, 

 Oregon and Washington. 



But once one has topped the summit of the 

 rock-ribbed back-bone of the mountains of the 

 Pacific States, a stretch of nearly fifteen hun- 

 dred miles of ill-nourished land lies before him 



