WILD GARDENS OF THE Y0SEM1TE PARK 139 



material together, mud particles and boulders 

 fifty feet in diameter : water, whether in oozing 

 currents or passionate torrents, discriminates both 

 in the size and shape of the material it carries. 

 Glacier mud is the finest meal ground for any 

 use in the Park, and its transportation into lakes 

 and as foundations for flowery garden meadows 

 was the first work that the young rivers were 

 called on to do. Bogs occur only in shallow 

 alpine basins where the climate is cool enough 

 for sphagnum, and where the surrounding topo- 

 graphical conditions are such that they are safe, 

 even in the most copious rains and thaws, from 

 the action of flood currents capable of carrying 

 rough gravel and sand, but where the water 

 supply is nevertheless constant. The mosses 

 dying from year to year gradually give rise to 

 those rich spongy peat-beds in which so many of 

 our best alpine plants delight to dwell. The 

 strong winds that occasionally sweep the high 

 Sierra play a more important part in the distri- 

 bution of special soil-beds than is at first sight 

 recognized, carrying forward considerable quan- 

 tities of sand and gravel, flakes of mica, etc., and 

 depositing them in fields and beds beautifully 

 ruffled and embroidered and adapted to the wants 

 of some of the hardiest and handsomest of the 

 alpine shrubs and flowers. The more resisting 

 of the smooth, solid, glacier-polished domes and 

 ridges can hardly be said to have any soil at all, 



