THE MAKE OF THE DESEET 



33 



rainfall each year. Even Sahara gets its occa- 

 sional showers, and the Colorado and the Mo- 

 jave show many traces of the clond-burst. The 

 dark thunder-clouds that occasionally gather 

 over the desert seem at times to reserve all their 

 stores of rain for one place. The fall is usually 

 short-lived but violent ; and its greatest force 

 is always on the mountains. There is no sod, 

 no moss, to check or retard the flood ; and the 

 result is a great rush of water to the low places. 

 In the canyons the swollen streams roll down 

 bowlders that weigh tons, and in the ravines 

 many a huge barranca is formed in a single 

 hour by these rushing waters. On the lomas 

 and sloping valleys they are not less destructive, 

 running in swift streams down the hollows, and 

 whirling stones, sand, and torn bushes into the 

 old river-beds. 



In a very short time there is a great torrent 

 pouring down the valley a torrent composed 

 of water, sand, and gravel in about equal parts. 

 It is a yellow, thick stream that has nothing but 

 disaster for the man or beast that seeks to swim 

 it. Many a life has been lost there. The great 

 onset of the water destroys anything like buoy- 

 ancy, and the tendency is to drag down and 

 roll the swimmer like a bowlder. Even the 



Cloud- 

 bursts. 



Canyon 

 streams. 



Dcaert 

 floods. 



