242 OUR NATIONAL PARKS 



leaning bushes and grass; the larger streams 

 and rivers in the canons displaying noble purity 

 and beauty with ungovernable energy, rushing 

 down smooth inclines in wide foamy sheets fold 

 over fold, springing up here and there in mag- 

 nificent whirls, scattering crisp clashing spray for 

 the sunbeams to iris, bursting with hoarse rever- 

 berating roar through rugged gorges and boulder 

 dams, booming in falls, gliding, glancing with 

 cool soothing murmuring, through long forested 

 reaches richly embowered, — filling the grand 

 canons with glorious song, and giving life to all 

 the landscape. 



The present rivers of the Sierra are still young, 

 and have made but little mark as yet on the 

 grand canons prepared for them by the ancient 

 glaciers. Only a very short geological time ago 

 they all lay buried beneath the glaciers they 

 drained, singing in low smothered or silvery 

 ringing tones in crystal channels, while the sum- 

 mer weather melted the ice and snow of the sur- 

 face or gave showers. At first only in warm 

 weather was any part of these buried rivers dis- 

 played in the light of day ; for as soon as frost 

 prevailed the surface rills vanished, though the 

 streams beneath the ice and in the body of it 

 flowed on all the year. 



When, toward the close of the glacial period, 

 the ice mantle began to shrink and recede from 

 the lowlands, the lower portions of the rivers were 



