64 RECONNAISSANCE OF PAET OF WESTERN ARIZONA. 
differ in physical character from the lower 1,000 feet, which is pre- 
sumably a river deposit. The coarseness of the sediment and the 
absence of terraces along the margin are unfavorable to the supposi- 
tion that the valley was transformed into a lake separated from the 
river. It is more probable that the water of the river continued to 
flow through the temporary lake, filling it rapidly with sediment or 
even building above the level of the dam before being finally deflected 
from its former course. A general view of the aggraded valley floor 
and its relation to the neighboring hills is shown in PI. XI. 
While accumulation was going on in the Detrital-Sacramento 
Valley other valleys and basins were filling with sediment. The Big 
Sandy, probably flowing at that time west of the Artillery Mountains 
and through the Cactus Plains to the Colorado, was evidently build- 
ing up its course, and the Hualpai Valley, probably at first a lake 
basin, was filling with sediment. Briefly stated, it is probable that 
the Temple Bar conglomerate is a part of the widespread accumulation 
which occupies the low places of the Southwest from central New 
Mexico to California and northward over the entire basin region. 
The probability that sedimentation over a wide area was due to a 
single far-reaching cause or group of causes constitutes one of the 
principal reasons for correlating the Temple Bar conglomerate with 
the Lake Bonneville beds and less confidently with the Gila con- 
glomerate. It is not the author's intention to argue that these beds 
are exact equivalents. They apparently belong, however, to a single 
division of time, like the Pleistocene epoch of the Quaternary. 
It may not be out of place, furthermore, to reiterate the statement 
that the reconnaissance surveys were inadequate for the final solution 
of the broad problems which, on account of their local bearing, must 
of necessity be discussed. The age of the Temple Bar conglomerate 
and its relation to other similar deposits, the changes in the course 
and activities of Colorado River, and the causes of these changes, 
are all problems to be finally solved only after much more extended 
investigation. 
River diversion. — The extensive aggradation caused some of the 
streams to abandon their old courses, and the sand and gravel filling 
the valleys were in some cases covered with angular wash. A not- 
able occurrence of the diversion of a river and the burial of its gravels, 
in the Salt River Valley, has been described by the writer," who shows 
that Salt River, which now flows north of the Salt River Mountains, 
formerly joined the Gila east of these mountains, about 40 miles 
farther upstream. 
Colorado River left the Detrital-Sacramento Valley and established 
a new course west of the Black Mountain Range, from Boulder Canyon 
a Lee, W. T., Underground waters of Salt River Valley, Arizona: Water-Supply Paper U. S. Geol. 
Survey No. 136, 1905, pp. 125-127. 
