18 RECONNAISSANCE OF PART OF WESTERN ARIZONA. 
conglomerate described by Gilbert" from the Gila Valley; by Ran- 
some 6 from the vicinity of Globe, Ariz.; by Lindgren c from eastern 
Arizona, and by the present writer d from the Salt River Valley in 
central Arizona. The greater part of the Temple Bar conglomerate, 
however, is not usually so well consolidated as the Gila conglomerate, 
although in places, especially where the older portions are exposed, 
it is as firmly cemented. 
In constitution and general appearance the formation resembles 
the Lake Bonneville beds of Utah described by Gilbert e as Quater- 
nary. The correlation, however, is based mainly on physiographic 
evidence, the discussion of which is included under " Geologic his- 
tory," and, for the sake of clearness, is placed after the section on 
descriptive details. 
Chemehuevis gravel. — Chemehuevis is here applied to a series of 
gravels that lie unconformably upon the Temple Bar conglomerate 
in the terraced bluffs along Colorado River from Grand Canyon to 
the Gulf. In the open valleys south of Black Canyon they form the 
conspicuous bluffs seen in characteristic development from Bulls 
Head southward. The name is derived from the Chemehuevis 
Valley, south of The Needles. The gravels are about 700 feet in 
maximum thickness, but occupy a measurably narrow belt along 
the river, having been deposited as valley filling during an aggrading 
stage of Colorado River. (See p. 65.) Their unconformable relations 
with the Temple Bar conglomerate and their unconsolidated condition 
render it probable that they are of late Quaternary age. 
Basalt flows. — Included in the Temple Bar conglomerate in many 
places, and sometimes overlying that conglomerate, are sheets of 
basalt from a few feet to 800 feet in thickness, in some places occu- 
pying large areas. These are younger than the basalts which were 
described on page 16 as having perhaps been outpoured at the close 
of the Tertiary and which underlie the Temple Bar conglomerate. 
GEOGRAPHIC AND GEOLOGIC DETAILS OF HIGHLANDS. 
GRAND WASH CLIFFS. 
Location. — The Grand Wash Cliffs, located in the northeastern 
part of the area described, form an escarpment extending from 
Music Mountain northward beyond Colorado River. They constitute 
the boundary between the High Plateau or Grand Canyon district to 
the east and the low-lying Basin region to the west. 
a Gilbert, G. K., U. S. Geog. Surv. W. 100th Mer., vol. 3, pt. 5, 1875, p. 540. 
bRansome, F. L., Geology of Globe copper district, Arizona: Prof. Paper U. S. Geol. Survey No. 12, 
1903, pp. 47-51. 
"Lindgren, Waldemar, The copper deposits of the Clifton-Morenci district, Arizona: Prof. Paper 
U. S. Geol. Survey No. 43, 1905, pp. 75-77. 
d Lee, W. T., Underground waters of the Salt River Valley, Arizona: Water-Supply Paper U. S. Geol. 
Survey No. 136, 1905, pp. 111-114. 
« Gilbert, G. K., Lake Bonneville: Mon. U. S. Geol. Survey, vol. 1, 1890. 
