142 GUIDEBOOK OF THE WESTERN UNITED STATES. 
The railway company sank a well 1,004 feet deep at Yucca some 
years ago which yields a supply of excellent water rising within 104 
feet of the surface.t. The east face of Black Mesa 
Yucea- continues in view beyond Yucca. The general suc- 
pavation Lstt feet. cession of beds in this face is shown in figure 36. 
‘opulation 138.* ‘ Te 
KansasCity 1,461 miles. Lhe rocks present considerable variety, comprising 
light-colored lavas (rhyolites) and black lava (basalt) 
in widespread sheets of varying thickness, separated by thick de- 
posits of light-colored tuffs, which were thrown out of volcanic 
vents in fragmentary condition. Extensive cuts in this volcanic 
series through a southern projection of the mesa show massive 
breccia and tuff capped by a sheet of light-colored lava (rhyolite). 
The breccia consists of large fragments of volcanic rocks of various 
fare Te Aust fe peices 
aa tea ng Wie ee tine age ee 
PIRES IAP I 
BLS AW Spear RIA 
BP Serie tigt ees ama 
Tithe 
ik Ny eee Oe le a artel 
omerate- eine ol 
087 894.955 Te De 
FIGURE 36.—Section showing succession of volcanic rocks in east face of Black Mesa, northwest of 
: Yucca, Ariz. : 
kinds, and some of the material appears to have flowed out mixed 
with hot water. Beyond this point the railway swings to the west 
around the south end of Black Mesa, but it continues to follow Sacra- 
mento Wash to Colorado River at Topock. 
ONE A short distance west of Haviland siding are low 
Elevation 1,465 feet aie shes — Somponed a the valley filling, and 
Kansas City 1,467 miles, 2t Milepost 547 is a railway cut through one of these, 
exposing from 30 to 50 feet of bowlders and sand. 
At Powell Colorado River is in sight to the northwest, occupying 
a broad valley between typical desert ranges. About 2 miles beyond 
Powell there may be seen in the foothills of the 
Ea rugged mountains to the south a hole through a 
Kancascity 1,180 niles, Pe? , Which is known as the ‘‘Eye of the Needle.” 
It has been eroded in a narrow ridge, largely by 
wind-blown sand, which is an effective agent of rock sculpture in the 
arid regions. 
Powell. 
1 The water comes from a mass of tuff lying at depths of 555 to 805 feet. This tuff 
is underlain by 22 feet of dark lava, 78 feet of tuff; and 99 feet of “‘granite,’’” 
