234 
THE GBANX) CASOIST DISTRICT. 
NATURE AND EXTENT OF THE WATER SUPPLY OF THE COLORADO. 
The dipper tributaries of this river* have their sources in lofty regions 
which are abundantly watered. But the trunk river itself and its dower 
tributaries, and also the lower portions of the Green and Grand Rivers, flow 
through regions which are exceedingly arid. Of the body of water which 
flows through the Grand Canon all but a small portion comes from the far 
distant highlands. The quantit}' contributed by the middle regions is very 
small. Although there are numberless water-ways opening into the great 
chain of canons, only a very few of them carry perennial streams, and 
these few living streams are mostly very small. The remainder, constitut- 
ing by far the greater number of tributary chasms, convey spasmodic floods 
for a few days or hours at a time when the snows are melting, or when the 
infrequent showers and storms prevail. The river, however, receives acces- 
sions to its volume of water in the following manner. The country trav- 
ersed by its middle courses is deeply scored with a vast number of profound 
side canons, and the main stream itself flows at a depth varying from 1,000 
to 6,000 feet below the general surface of the adjoining country. The 
water which falls upon the country is in great part absorbed by the rocks 
and sinks into the depths, where no doubt it finds subterranean channels. 
Surface springs are exceedingly rare, but in the depths of the main chasm 
and in the bottoms of the side chasms near the river the springs are plenti- 
ful, and in many cases very copious, sending forth clear sparkling waters, 
beautiful to the sight, but sometimes heavily charged with obnoxious salts. 
In the Grand Canon especially ai-e many springs of water, and not a few 
considerable streams of large volume emerging from the rocks in the lower 
depths. Most of them are good and fresh, and a few are saline and hot. 
The body of water thus supplied to the river is quite considerable, and it 
is important here to note the fact that it brings no sediment. 
Between the junction of the Green and Grand and the lower end of 
* Mr. Henry Gannett, geographer of the census, makes the total area of the drainage system of 
the Colorado 255,049 square miles, being second in extent of all the rivers of the United States which 
reach the ocean. That part of this drainage area which lies above the Grand Wash is given roughly 
at 165,000 square miles. 
