SOUTHERN PACIFIC LINES 171 
this region, and it was also a great resort for the Indians of later times, 
who found water and good hiding places in the numerous canyons. 
In the San Simon Valley at Rodeo and for some distance above and 
below considerable water is available in the sand and gravel of the 
valley fill, mostly at depths of 300 to 400 feet. It has been exten- 
sively utilized by wells and the water applied to irrigation with excel- 
lent results. According to Schwennesen most of the wells penetrate 
two water-bearing beds, and some of them more. In the central 
part of the valley, in the vicinity of Rodeo, the first water-bearing 
beds are from 70 to 80 feet deep, the second from 90 to 100 feet, and 
the third at about 150 feet. Near Apache the depths are slightly 
greater. In the San Simon Cienega, 15 miles north of Rodeo, the 
water comes to the surface in a small area. A well pumped at Rodeo 
station yields about 200 gallons a minute, and at that rate the water 
level is lowered 22 feet. The total solids in the well water of this 
region are only 160 to 364 parts per million, and the principal salt is 
sodium carbonate. 
Two miles southwest of Rodeo the State of Arizona (see p. 147) is 
entered. The course of the railroad is 8. 30° W. through Mora and 
Apache sidings and nearly to Chiricahua siding, ascending the wide 
grassy flat-bottomed valley of San Simon Creek. It skirts the bold 
east front of the Chiricahua Mountains, broken by deep canyons up 
which are vistas of the high central range with its forest covering. 
From a point near Mora siding there is an especially fine view of this 
kind up Horseshoe Canyon. East of the railroad are the steep slopes 
of the Peloncillo Mountains, consisting of volcanic rocks similar to 
those on the opposite side of the valley. They lie nearly horizontal, 
although northeast of Rodeo the succession is tilted to the southeast. 
Beyond Apache a prominent butte (Squaw Mountain) west of the 
railroad shows a block of part of the volcanic succession dipping east 
and probably separated by faulting along its west side. Near by are 
the remains of a very old Indian settlement of considerable extent. 
Not far beyond Apache siding the headwaters of the San Simon Valley 
are crossed, and here begins a flow of black lava (basalt) which occu- 
pies a wide area in the valley and extends south to the international 
boundary. *° The lava is very fresh and evidently the product of an 
eruption in Recent geologic time from vents now marked by cinder 
cones, several of which are visible not far east and southeast of Ber- 
nardino siding. The relations of the scoria, bombs, and lapillae in 
2? The lava is black and cellular, and [| the valley. As its area widened the 
although the sheet is not very thick it 
presents a surface of extreme irregu- 
larity, closely resembling some of the 
recent flows in other parts of the world. 
Apparently most of the lava welled out 
of cracks and spread over the bottom of 
surface congealed and the hot lava 
broke out from underneath, 
tunnels caved-in areas. 
That the molten lava was filled with 
steam is shown by the scoriaceous or 
honeycombed character of the rock. 
