THE WORK OF RUNNING WATER 



53 



THE EROSIVE WORK OF STREAMS 



Streams carry sediment down their valleys, as may be seen when 

 rivers are in flood, for at such times they are usually muddy. Be- 



Fig. 42. Streams starting in the mountains at the right, disappear in the 

 sand, gravel, etc. on the arid plain in the center. Scale 4 miles per inch. 

 (Paradise, Nev. Sheet, U. S. Geol. Surv.) 



sides the mud which is in the water, streams roll sand, gravel, etc., 

 along their bottoms. The movement of the fine sediment of the 

 stream, and of the coarse sediment at its bottom, may be seen in 

 any little current along the roadside after a shower, and the great 



