SOUTHERN PACIFIC LINES 287 
placements. (Eaton.) Faulting has had much to do with the accumu- 
lation of the oil. The most productive fields are on anticlines having 
the form of elongated domes, but some of the folds are of the plunging 
variety, with their upper Side sealed by asphalt or by an overlapping 
impervious bed. (Kew.) 
YUMA, ARIZ., TO SAN DIEGO, CALIF. 
Sleeping cars from several trains continue westward from Yuma to 
San Diego over the San Diego & Arizona Railway, which is allied 
with the Southern Pacific lines. The distance is 218 miles, across 
Imperial Valley and the high sierra of southern California, with two 
long detours into Baja California. This railroad was completed in 
1919 at a cost of $19,000,000. It has 22 tunnels, one of them about 
half a mile long. 
The main line is left at Araz Junction, 64 miles west of Yuma, on 
Southern Pacific tracks extending to El Centro (40 miles). The 
railroad passes around the southeast end of the great 
ade belt of sand hills and looping into Mexico reaches 
ltkcick basa. Mexicali, Mexico, and the adjoining city of Calexico, 
New Orleans 1,830 Calif. El Centro is in the highly productive irrigated 
— district of Imperial Valley. (See p. 248.) The New 
River, an old channel from the Colorado River, touched by the 
railroad at Calexico and crossed a short distance west of Seeley, 
occupies a trench in the desert plain much deepened and widened by 
the great flood of water that ran through it into Imperial Valley from 
the Colorado River in 1905. This stream ate deeply into the adjoin- 
ing banks and damaged more than 7,000 acres of the adjacent region. 
The Alamo River, 10 miles east of El Centro, was another inlet for 
flood waters. 
From Seeley westward there are fine views of Signal Mountain, 
a knob of old granite and schist not far away in Mexico, and of the 
Sierra de las Cocopas, consisting of volcanic rocks, which extend far 
to the south. Farther west is dimly outlined the high Sierra Pedro 
Martir (mar-teer’), in Baja California, which attains an elevation of 
more than 10,000 feet. It consists of light-colored granite. The 
northern extension of this range, known as the Laguna Mountains, 
is crossed by the railroad near Jacumba, about 50 miles farther on, 
where, however, the elevation is much less than in Mexico. The 
continuity of its steep eastern front, believed to be a fault scarp, is a 
striking feature for many miles. The West Line Canal, just east of 
Dixieland, separates the productive irrigated land, with its fine fields 
of cotton, alfalfa, barley, and maize, from the original desert, with its 
spate outer: of arid-land plants. 
El Centro. 
