SOUTHERN PACIFIC LINES 105 
large boulders and to transport a vast amount of fine material far 
down the side slopes. These floods often cut deeply into the rail- 
road embankments, so that it is necessary to provide long deflection 
ditches and dikes to prevent serious washouts. This item is as 
expensive as flood protection and repair in regions where there are 
large rivers subject to freshets. The run-off is very rapid in the 
deserts, because the rocks are bare, the soil is hard, and most of the 
slopes are steep. But little water passes underground, and springs, 
even in the mountains, are exceedingly rare. Much water, moreover, 
is lost by evaporation. 
At Lobo are wells which afford water for locomotive supply and 
local use. A noticeable feature here is a large stone building erected 
. by the railroad company as a hotel; it did not succeed, 
obo. : 
ric bak ack however, and is now used as a ranch house. The 
Population 30.* prominent mountain about 7 miles east of Lobo con- 
cont omgea ss 054 sists of quartz syenite of igneous origin, and there is 
another large intrusion of this rock in the northeastern 
part of the Van Horn Mountains just west of Lobo. It was forced in 
molten condition into strata of Permian and Lower Cretaceous age, 
probably in early Tertiary time. 
SIDE TRIP TO CARLSBAD CAVERNS, N. MEX. 
At Lobo passengers can make arrangements for motor transpor- 
tation to Carlsbad Caverns by way of Van Horn, a distance of about 
100 miles nearly due north. The route is shown in Figure 17. There 
are regular busses and a 1-day airplane excursion from El Paso to 
the caverns, a distance of 140 miles. The caverns are on the south- 
east slope of the Guadalupe Mountains and extend far and deep 
underground in a series of superb chambers containing a great variety 
of beautiful stalactites, stalagmites, and other depositional forms of 
calcium carbonate. (See pl. 16, B.) The road northward from 
Van Horn skirts the outlying ridges of Beach and Baylor Mountains 
and the foot of the Sierra Diablo, on the west side of Salt Basin, a 
wide desert valley of which the Lobo Flats are a southern extension. 
This valley is without outlet. The mountains adjoining it consist 
mainly of limestones and sandstones lying nearly horizontal and 
presenting a most interesting succession of 5,000 feet or more of 
152109°—33-——_8 
