THE SEA AND THE DESERT 205 



have spoken of the Gila as a rushing mountain 

 torrent in the vicinity of Riverside, and at 

 Florence it was considerable in volume, though 

 somewhat smaller. Now, the Gila is one of the 

 chief branches of the Colorado River, joining it 

 in the vicinity of Yuma; but there are long 

 stretches of the Gila between Florence and Yuma 

 which, save in times of extreme freshet, do not 

 present any water at the surface. 



Mineral Creek was a very pretty mountain 

 creek high up in the Finals. The farther one 

 travelled its course from its source to where it 

 joined the Gila, the less evident became the water 

 at the surface. First it was a brook of consider- 

 able extent, then it became a series of detached 

 pools. These occurred presently at long inter- 

 vals, and finally, for the last fivQ miles, the stream 

 was traceable only by the dry bed which carried 

 the superfluous water of freshet times. I may 

 summarize the situation by saying that the char- 

 acteristic of the watercourses of Arizona is the 

 sinking below the surface of the visible stream as 

 soon as the arid stretches of desert away from the 

 mountains are reached. The alluvium at these 

 points, besides being dry and parched and of 

 great depth, is sufficiently loose and gravelly to 

 allow even great streams of water to percolate 

 through and flow as streams, when bed-rock is 

 attained often far below the surface. 



