234 GENERAL SCIENCE 



spring. Now as a rule forests give the snow some pro- 

 tection from the direct rays of the sun and so delay its 

 melting; but this snow will go off rapidly when a warm 

 rainy season comes. The snow water and rain usually 

 give the river channels more water than they can carry 

 and a flood results. Where there are no forests the snow 

 on the southern slopes is usually melted by the direct 

 rays of the sun, and the water from it is gone and out of 

 the way before the snow on the northern slopes is melted 

 directly by the sun or by warm rains. The snow on the 

 eastern and western slopes will melt gradually between 

 the melting of that on the southern and northern slopes 

 where there is no forest. A flood caused by the melting 

 of snow by rain is general and affects the large rivers as 

 well as the small streams. This first cause is in favor of 

 the deforested, region or sections and against the forests. 

 Second. The second cause is in favor of the forested 

 regions. By careless methods of agriculture many 

 deforested fields and slopes are unprotected by any kind 

 of vegetation. This bare, wornout soil, having lost 

 its ability to receive and retain water because of the loss 

 of its humus, does not permit much of the water to soak 

 down into it, and so the water rushes rapidly down the 

 slopes and into the larger streams, carrying a large 

 quantity of sediment, clay, sand, and rock. The larger 

 creeks that do not flow so rapidly are not able to transport 

 the heavy load of solid matter delivered to them, and 

 so their beds become choked with gravel and rock. A 

 creek bed almost full of sediment does not require much 

 water to fill it, and the result is that the excess of water 

 during a rainy season is spread over the valley on either 

 side. These creeks during their flood stages deliver more 

 sediment to the rivers than they are able to move along, 



