252 OUR NATIONAL PARKS 



broad masses are launched over the brows of 

 cliffs three or four thousand feet high, which, 

 worn to dust by friction in falling so far through 

 the air, oftentimes hang for a minute or two in 

 front of the tremendous precipices like gauzy 

 half-transparent veils, gloriously beautiful when 

 the sun is shining through them. Most of the 

 canon avalanches, however, flow in regular chan- 

 nels, like the cascades of tributary streams. 

 When the snow first gives way on the upper 

 slopes of their basins a dull muffled rush and 

 rumble is heard, which, increasing with heavy 

 deliberation, seems to draw rapidly nearer with 

 appalling intensity of tone. Presently the wild 

 flood comes in sight, bounding out over bosses 

 and sheer places, leaping from bench to bench, 

 spreading and narrowing and throwing off clouds 

 of whirling diamond dust like a majestic foamy 

 cataract. Compared with cascades and falls, 

 avalanches are short-lived, and the sharp clashing 

 sounds so common in dashing water are usually 

 wanting ; but in their deep thunder tones and 

 pearly purple-tinged whiteness, and in dress, 

 gait, gestures, and general behavior, they are 

 much alike. 



Besides these common storm avalanches there 

 are two other kinds, the annual and the century, 

 which still further enrich the scenery, though 

 their influence on fountains is comparatively small. 

 Annual avalanches are composed of heavy com- 



