12 HYDROGRAPHIC REPORT. 
and rocky there is nearly always a good channel and a sandy bed. If the land on either side 
is low, pebbles are washed down into the steam and overspread the bottom. 
At the mouth of the Mojave cajion the Colorado is divided by a pebbly island, on both sides 
of which are sharp rapids. The eastern channel is preferable to the other. The water has 
a depth of three feet, but the bottom is gravelly, and some scattered pebbles of large size 
come within two or two and a half feet of the surface. The rapid is one or two hundred yards 
in length. In ascending, a line should be taken from the bow to an anchor ahead, to prevent 
the boat. in case she should catch upon a rock, from being swung around. If the bow were 
to be whirled back it would be with such violence that an encounter with a rock would occasion 
serious damage. 
In the Mojave valley the river generally is good. At the entrance from the Needles is a 
broad, difficult shoal, covered with pebbles. Four miles above Camp 41, abreast of Camp 45, 
and at the very head of the valley, are also rocky bars, attended with slight rapids. The bed 
generally is less gravelly than in the Chemehuevis valley. The channel is little obstructed by 
sand bars. One only was found near Camp 44, where for fifteen or twenty yards there were 
but eighteen inches of water. The average depth of the channel continues to decrease. In 
the Mojave valley it is about six feet. 
This section of the Colorado, it will be seen, differs from the two preceding, principally in 
the character of the river bed, which, as high as the mouth of Bill Williams’s Fork, is com- 
posed entirely of sand, but is afterwards found to be partially covered with gravel. At all of 
the gravelly bars the current is swift, and frequently assumes the character of a rapid. Such 
places present, of course, more difficulty than the sand bars; but though, from this reason, the 
bad places are worse, the channel generally is freer from obstructions than it is below. When 
the water rises the gravel bars do not experience any change, and during a higher stage they 
would occasion no trouble. At such times the navigation of this section would doubtless be 
easier and better than that of any other portion of the Colorado. 
PYRAMID CANON TO BLACK CANON. 
This section comprises the remainder of the navigable portion of the Colorado. It is sixty 
miles in length. In the Pyramid cajion, which is five or six miles long, the navigation is good. 
Above, the bed of the stream is composed generally of coarse gravel and rocks. Rapids occur 
at short intervals throughout the whole distance. The first, at the head of the cafion, has a 
depth of two and a half feet. Two or three small rapids which follow present no great 
difficulty. At Deep rapid the channel is narrow, and the rush of water stronger than at any 
place below the Black cafion, but in the centre of the channel there is a depth of six feet, and 
there are no rocks to obstruct the passage. There is good holding ground above for an 
anchor, to which a line may be attached to keep the bow steady. The rapid above occurs at 
a sharp turn of the river, but is not difficult to pass. 
At Shallow rapid there are only twenty-two inches of water. An island divides the river 
into two channels. The current is rather stronger on the west side, but the river is narrower, 
and the abrupt bank, covered with trees, offers better places to which to attach aline. The 
two rapids above Camp 50 are easy. At the first there is plenty of water, and at the second 
nearly two and a half feet. The other rapids below the head of Cottonwood valley have at 
least three feet of water and a moderate current. Through the Painted caiion the navigation 
is good. Near Mount Davis the edges of the channel are obstructed by rocks, but a sufficiently 
- wide space in the middle is left clear. caiice ial 
Round island should be passed on the eastern side. There is a pair of rapids abreast of the 
island. At the first there is plenty of water, but at the second, for several yards, a depth of 
only eighteen inches. At the rapids between Camps 53 and 54 there is sufficient depth. At 
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