o^ 



2 GLACIAL AND SITEFACE GEOLOGY OF THE PACIFIC COAST. 



winds and their proximity to the ocean, glaciers exist in abundance above 

 the 49tli parallel, and increase in size as we follow the chain towards 

 the northwest. Below the 51st parallel they only occur high up in the 

 ran^e ; but, north of that, begin more and more to extend down the valleys, 

 and finally, in still higher latitudes (about 60°), come nearly or quite to the 

 sea. 



Returning to our own territory, the conditions as to the present distribu- 

 tion of snow on the Great Basin ranges, and in the higher portions of the 

 Rocky Mountains, between the parallels of 37" and 43°, may be noticed. In 

 all this region, as before remarked, there are, so far as known, -no active 

 glaciers, with the exception of the very small ones recently discovered near 

 the summits of one or two of the highest points of the Wind River Range. 

 The condition of this region, as respects snow accumulations, resembles 

 much that already described as prevailing in the Sierra Nevada, but, on the 

 whole, with less fluctuation from year to year. 



The mountains nearest the Sierra on the east, the Inyo and White Moun- 

 tain ranges, have their precipitation cut off almost entirely by the more ele- 

 vated range on the west. The contrast between the amount of rain and snow 

 fdl on the Invo Range and tlie Sierra Nevada is most striking. The former 

 runs parallel with the latter, is not very much inferior to it in elevation, and 

 the crests of the two ranges are hardly more than twenty miles apart, a valley 

 some 10,000 feet deep intervening. Yet hardly any snow or rain falls on 

 the Inyo Range, which is quite destitute of any streams on either flank, and 

 indeed furnishes hardly water enough to keep the explorer from perishing 

 with thirst. At a time of the year (May, 1872) when the Sierra was deeply 

 covered with snow for from 2,000 to 3,000 feet below the sunmiit of the 

 range, the Inyo Mountains opposite liardly showed the smallest trace of it. 



Snow remains in patches on the highest points of the most elevated ranges 

 of the Great Basin, especially the East Humboldt, through the whole year ; 

 but the amount still left at the close of the drier seasons mast sometimes be 

 exceedingly small. There are no statistics of the precipitation on these 

 ranges, )jut there can be no question that it is small, as compared with that 

 on the Sierra Nevada. As we approach the eastern edge of the Cordilleras, 

 the regimen of the climate changes somewhat, the rain and snow fall being 

 no longer limited essentially to the winter season, but extending over the 

 whole year. Still, in spite of its more equal distribution, the quantity does 

 not appear to be as large as it is on the Sierra. The writer, with a small 



