SOUTHERN PACIFIC LINES 279 
Puente is the center of a great walnut district which produces more 
than 13,000,000 pounds of walnuts a year (1929). Near Puente the 
railroad leaves the valley of San Jose Creek and the 
Puente Hills and passes into the wide basinlike plain 
bordering San Gabriel Wash, into which flows the 
asi sts aye 1,982 San Gabriel River, a stream that rises in deep canyons 
; far back in the San Gabriel Mountains. This wash 
is crossed a mile west of Bassett, but there is usually little water in it 
here except during rainy seasons. The river water is used for irriga- 
tion, but much of it is underground, where it is available for pumping. 
Some of this underflow comes out again in Lexington Wash, near El 
Monte. In times of freshet a large volume of water passes down San 
Gabriel Wash, as may be inferred from the large boulders in its bed. 
These boulders are crushed for road material. 
From Bassett to San Gabriel the railroad goes northwest across a 
broad plain, most of which is in a high state of cultivation, with 
numerous fruit and walnut orchards, beautiful gardens, and verdant 
fields, all irrigated by water pumped from the underflow. 
As the train progresses northwestward the San Gabriel Mountains 
are approached and there are fine views, notably of San Gabriel Peak 
(elevation 6,152 feet). This great mountain range consists of a huge 
block of the earth’s crust uplifted along profound breaks, one of which, 
the Sierra Madre fault, follows the south foot of the range, and another, 
the San Andreas fault, extends along its northern margin. These are 
very recent faults, for the main upheaval was at the end of Tertiary 
(Pliocene) time. Doubtless there was a prior mountain range in 
front of the site of the present San Gabriel Mountains, which furnished 
sediments to the pre-Pliocene formations, but the form and relations 
of mountains and plains at that time can hardly be conjectured. An 
uplift of this kind may have progressed very slowly. There was not 
only the general axial uplift of the range but cross faulting, which 
has broken the main block into huge fragments with varying degrees 
of tilt and amount of uplift. The planes of the main faults dip steeply 
to the south, at least in the west end of the range, so that the granite 
and gneiss of the range are relatively thrust over the strata of Tertiary 
age, which are considerably flexed and in places also faulted. (M. L. 
Hill.) In the portion of the range north of Los Angeles the rocks are 
schist, quartzite, and marble, old sediments greatly metamorphosed 
and penetrated by a large amount of igneous rocks. Granite invades 
the metamorphic rocks very extensively, and there are also large 
masses of diorite and granodiorite and some hornblendite. (W. J. 
Miller.) 
Puente. 
Elevation 320 feet. 
034. 
