FOUNTAINS AND STREAMS 245 



siderable distances, groping their way in the 

 dark like the draining streams of glaciers, and 

 at last bursting forth in big generous springs, 

 filtered and cool and exquisitely clear. Some of 

 the largest look like lakes, their waters welling 

 straight up from the bottom of deep rock basins 

 in quiet massive volume giving rise to young 

 rivers. Others issue from horizontal clefts in 

 sheer bluffs, with loud tumultuous roaring that 

 may be heard half a mile or more. Magnificent 

 examples of these great northern spring foun- 

 tains, twenty or thirty feet deep and ten to 

 nearly a hundred yards wide, abound on the 

 main branches of the Feather, Pitt, McCloud, 

 and Fall rivers. 



The springs of the Yosemite Park, and the 

 high Sierra in general, though many times more 

 numerous, are comparatively small, oozing from 

 moraines and snowbanks in thin, flat irregular 

 currents which remain on the surface or near it, 

 the rocks of the south half of the range being 

 mostly flawless impervious granite ; and since 

 granite is but slightly soluble, the streams are 

 particularly pure. Nevertheless, though they 

 are all clear, and in the upper and main central 

 forest regions delightfully lively and cool, they 

 vary somewhat in color and taste as well as tem- 

 perature, on account of differences, however 

 slight, in exposure, and in the rocks and vegeta- 

 tion with which they come in contact. Some 



