344 The Colorado River 
about four thousand feet below the surface of the surrounding 
country, would be of little service to those living away from its 
immediate line, and there is small chance to live along the 
line. In addition the floods in the Grand Canyon are enorm- 
Mukoontuweap Canyon, North Fork of the Virgen. 
Ten miles long, 3500 feet deep. 
Photograph by J. K. Hillers, U. S. Geol. Surv. 
ous and capricious. Sometimes heavy torrents from cloud¬ 
bursts plunge down the sides of the canyon and these would 
require to be considered as well as those of the river itself. 
To be absolutely safe from the latter the line would probably 
require, in the Grand Canyon, to be built at least one hundred 
