SOUTHERN PACIFIC LINES 281 
Indian word meaning crown of the valley. To the north are the high 
San Gabriel Mountains, with two conspicuous summits, Mount Lowe 
(elevation 5,650 feet) and Mount Wilson (5,750 feet), from both of 
which there are extensive views of the Los Angeles Plain. (See pl. 47). 
The Repetto Hills west and south of Alhambra consist of sandstone, 
conglomerate, soft siltstone, and shale of Miocene, Phocene, and 
possibly Pleistocene age, flexed in basins and arches. Part of the 
shale of upper Miocene age is diatomaceous. These rocks are of 
marine origin and indicate that during the later part of Tertiary time 
the region was submerged by the sea at intervals, and sand and mud 
were deposited in wide estuaries and along beaches. There was a 
long epoch of general subsidence, so that a great thickness of these 
materials accumulated. They have since been consolidated, uplifted, 
flexed, and faulted, and later terraces and plains have been developed 
on their surface. (Reed.) 
After passing out of this narrow belt of hilly country the railroad 
enters the coastal plain that extends south and west to the Pacific 
Ocean. This plain consists of lowlands abruptly margined to the 
north by the Santa Monica Mountains, Repetto Hills, Puente Hills, 
and Santa Ana Mountains. Much of the region is a plain sloping 
gently seaward, but its continuity is interrupted by hills and ridges 
of considerable prominence, such as the Baldwin Hills, Dominguez 
Hill, and Signal Hill. In general it is floored with alluvium derived 
from the adjoining highlands and the mountains to the north. Ina 
few places, however, the rocks have not yet been covered by alluvium. 
The plain is widest in the Los Angeles region, where it extends 25 
miles south from the Santa Monica Mountains and with an area of 
nearly 2,000 square miles constitutes the combined delta of the Los 
Angeles, San Gabriel, and Santa Ana Rivers. At its inner edge its 
elevation is mostly from 200 to 300 feet, and the seaward slope is 
10 to 20 feet to the mile. This plain, ith its fertile soil and delight- 
ful climate, is covered with settlements, cultivated fields, vineyards, 
and vast orchards of oranges, lemons, walnuts, olives, and other fruits. 
Shade trees and flowers are_extensively cultivated. To this wealth 
of resources on the surface is added a large production of petroleum, 
which has been developed most profitably at many places. 
The Los Angeles River is crossed in the eastern outskirts of the city 
of Los Angeles, and the train proceeds slowly through streets for about 
3 miles to the depot. Most of the city is built on low river terraces 
and on the inner edge of the coastal plain, but the newer sections 
extend onto the hills of folded and faulted Tertiary sandstone and 
shale that rise to the north. The Los Angeles River, like many other 
streams of the Southwest, is ordinarily of small volume, but during 
heavy rains it is considerably swollen, and at times it becomes a deep 
: torrent capable of doing considerable damage. 
152109°—-33-—_19 
