58 
The Colorado River 
35CHD feet below the surface at the end of Marble Canyon, 
which, separated only by the deep canyon of the Little Col¬ 
orado, is practically a northward continuation of the Grand 
Canyon itself. As the river runs, the Grand Canyon is 2\y^ 
Looking across the Grand Canyon (Inner Gorge) near the Foot of the Toroweap. 
Depth 3000 feet. 
Photograph by J. K. Hillers, U. S. Geol. Survey. 
miles long. To this may be added the 6^^ miles of Marble, 
giving a continuous chasm of 283 miles, the longest, deepest, 
and most difficult of passage in every direction of any canyon 
in the world. The depth begins with a couple of hundred feet 
