MOUNTAIN-BARRIERS 



215 



banks ; and that finally the streams, after 

 plunging through canyons, fall into the arroyos 

 and are drunk up by the desert sands before 

 they have left the mountain-bases. It seems 

 incredible that a stream should be born ; run its 

 course through valley, gorge, and canyon ; and 

 then disappear forever in the sands, all within 

 a few miles. Yet not one but many of these 

 mountain-streams have that brief history. 



And at one time they must have been larger, 

 or there were slips of glaciers or avalanches on 

 the mountains ; for the arroyos are piled with 

 great blocks of granite and there are rows of 

 bowlders on either side which might have been 

 rolled there by floods or pushed there by an ice- 

 sheet. As you draw nearer, the bowlders crop 

 out in large fields and beds. They surround 

 the rock bases like a deposit rather than a talus, 

 and over them one must pass on his way up the 

 mountain-side. 



If you ascend by the bed of the arroyo it is 

 not long before you begin to note the presence 

 of underground water. It is apparent in the 

 green of the vegetation. The grasses are seen 

 growing first in bunches and then in sods, 

 little blue flowers are blooming beside the 

 grasses ; alders, willows, and young sycamores 



Lost 

 streams. 



Avalanches 

 and bowl- 

 der-beds. 



The ascent 



bytlie 



arroyo. 



