50 THE WORLD'S LUMBER ROOM. 



and consequent rapidity of the current, as well as upon the 

 nature of the rocks with which it has to deal. 



Even a small rivulet when flooded will transport from one 

 to three thousand tons of gravel in a day ; and during the 

 rainy season in India, when every river and mountain torrent 

 are swollen, when for days and nights together nothing is 

 heard but the crash of trees and boulders, and great masses 

 of earth and rock, three or four thousand feet in length, fall 

 from the mountain side and are ground to sand and mud in 

 the boiling waters, the channel of every stream, great and 

 small, is enlarged, and enormous quantities of mineral matter 

 are carried down to the ocean. One river in Bengal removes 

 a depth of ninety feet of stone and earth from its bed every 

 year, and the Ganges brings down in the same time more 

 than enough solid material to build up forty-two Great 

 Pyramids. 



The Americans have a saying that in time of flood the 

 "Big Muddy," as they call the Missouri, is "too thick to 

 swim in and too thiri to walk upon." For winter in the North- 

 western States is long and severe ; the rivers, streams, and 

 brooks are all fast frozen, and the country is covered with 

 colossal heaps of snow, which sometimes attain well-nigh 

 fabulous dimensions. Then suddenly, almost without warn- 

 ing, comes the intense heat of summer ; the streams are set 

 free, the snow is melted with lightning rapidity, violent 

 torrents of rain fall, the brooks are swollen into rivers, the 

 rivers into boiling mud-laden floods, which at once burst 

 their bounds, inundate the valleys, overthrow trees, houses, 

 mills, and sweep away whole tracts of land in one place, 

 while they pile up immense islands 'and sand-banks in 



