THE SANTA FE ROUTE, 165 
times occur. For several years the United States Geological Survey 
gaged the flow in the gap and the stream was found to have an annual 
volume of 68,000 acre-feet, or a mean of 95 cubic feet asecond. One 
freshet carried 13,400 cubic feet a second but was not of long dura- 
tion. The water of Mohave River is now used for irrigating about 
15,000 acres, mostly in alfalfa, grain, and garden truck. 
At milepost 39, 2 miles south of Victorville, the train leaves the 
bank of Mohave River and, entering a small valley, begins to climb 
the steeper part of the long ascent of about 1,000 feet toward the 
high mountain ranges which lie between the Mohave Valley and the 
coastal region of southwestern California. The course of the railway 
continues nearly due south. The slope, which is the southern edge 
of the Mohave Desert, consists of a thick succession of sheets of 
gravel and sand which extend far up the mountain sides and beyond 
the summit at Cajon (cah-hone’) Pass. Near milepost 42 the railway 
has risen above the bottom lands of the Mohave Valley, and from 
this point southwestward for 10 miles or more there are fine views 
Sw. 
San Gabriet 
Mts. 
Figure 39.—Section through sand and gravel deposits of the sloping plain along the Santa Fe Railway 
north of the San Gabriel Mountains, near Victorville, Cal. 
of the great mountain ranges ahead. To the southeast and south, 
across the upper Mohave Valley, rise the San Bernardino Moun- 
tains; the ranges ahead and to the southwest are the San Gabriel 
Mountains. These two ranges come near together at Cajon Pass, 
which leads into a gap between them. Mohave River and many 
other streams deposited the sand and gravel of which the plain is built, 
but later they have cut deep valleys across it. The relations of this 
detrital deposit are shown in figure 39. 
A peculiar yueca, locally known as the Joshua tree (Yucca or 
Clistoyucca arborescens) is conspicuous on the grade up the mountains. 
(See Pl. XLI, A, p.168.) It begins with a few scattered trees below 
Victorville and becomes very abundant in the region about Hesperia 
and the slopes above, nearly to Cajon Pass, its upper limit being 
closely determined by the altitude and temperature. It is said that 
attempts have been made to utilize the fibrous trunk of the yucca 
for manufacturing pee but the tree is now used chiefly in making 
souvenirs and t 
