SOUTHERN PACIFIC LINES 213 
and pyrite. The road descends the valley of Pinal Creek for some 
distance past outcrops of dacite lava and rocks of the Apache group 
broken by many faults. (See fig. 55.) Beyond the small irrigation 
settlement of Wheatfield the north end of the Pinal Mountains is 
crossed. This ridge here consists mainly of coarse granite (probably 
pre-Cambrian), which to the north is capped by heavy lava flows of 
Tertiary age. From the summit, which is in a high saddle (elevation 
3,980 feet), there is a fine view of the valleys of the Salt River and 
Tonto Creek (tone’ toe), now flooded for many miles by the Roosevelt 
Reservoir. 
The broad old valley of the Salt River is floored and in part mar- 
gined with valley fill consisting mostly of gravel and sand, part of 
it bedded, and some fine sediments probably deposited in alake. The 
lake deposits are well exposed in badlands north of Roosevelt. As the 
road approaches Roosevelt there is a good view of the extensive Tonto 
cliff dwellings of aborigines in a deep alcove high in the cliffs about 
Barnes Peak 
i Mescal limesto 
: a Ke Spring quartzite sw 
So Lower division) 
si Ean: Dripping Spring quartzite 
om oat ae aa 
—Sill 
= 
’ _ — 
7 oy ii r a ef 
ee ae - see fares 
- “A; pet” ee ys Opso7 = ti Dit orerit ne ee ore 
f af PC TNS Se BS a hl Bs S ss / te’ yao AIA 
Bo 500 1 arene Feet 
L i 
FIGURE 55.—Section showing relations of Apache ee 7 miles northwest of Miami, Ariz. By F.L. 
Rans' 
2 miles southwest of the road. (See pl. 28, A.) One of them is a 
three-storied building, and there are also niaiiae structures, all of 
which have been abandoned for many centuries. There are also ruins 
of cliff dwellings in the Sierra Ancha, on the north side of the Salt 
River Valley. This high range of vides and plateaus consists of a 
thick succession of strata of the Apache group invaded by intrusive 
sills of diabase, as shown in Figure 56. Certain layers of the Mescal 
limestone have been altered to the chrysotile variety of asbestos, . 
which has been mined extensively for commercial use. Some of the 
refuse heaps at the workings are plainly visible from the road, as 
great white streaks high on the mountain slope. The value of this 
mineral varies greatly with quality. According to the Bureau of 
Mines the prices in 1931 ranged from $10 to $400 a ton. 
A short distance beyond the small village of Roosevelt the Roosevelt 
Dam (pl. 28, B) is reached. It is built across the entrance of the long, 
deep canyon cut through the mountains by the Salt River just below 
the confluence of Tonto Creek. The Salt River rises in the mountains 
