258 OUR NATIONAL PARKS 



basins gone, they are now fed only by small mo- 

 raine springs, whose waters are mostly evapo- 

 rated in passing over warm pavements, and in 

 feeling their way from pool to pool through the 

 midst of boulders and sand. Even the main 

 streams are so low they may be easily forded, 

 and their grand falls and cascades, now gentle 

 and approachable, have waned to sheets and webs 

 of embroidery, falling fold over fold in new and 

 ever changing beauty. 



Two of the most songful of the rivers, the 

 Tuolumne and Merced, water nearly all the Park, 

 spreading their branches far and wide, like broad- 

 headed oaks ; and the highest branches of each 

 draw their sources from one and the same foun- 

 tain on Mount Lyell, at an elevation of about 

 thirteen thousand feet above the sea. The crest 

 of the mountain, against which the head of the 

 glacier rests, is worn to a thin blade full of joints, 

 through which a part of the glacial water flows 

 southward, giving rise to the highest trickling 

 affluents of the Merced ; while the main drain- 

 age, flowing northward, gives rise to those of the 

 Tuolumne. After diverging for a distance of 

 ten or twelve miles, these twin rivers flow in a 

 general westerly direction, descending rapidly 

 for the first thirty miles, and rushing in glorious 

 apron cascades and falls from one Yosemite valley 

 to another. Below the Yosemites they descend 

 in gray rapids and swirling, swaying reaches, 



