Mountains of the South 243 



tains between the east and the west. Whether the two moun- 

 tain ranges, San Jacinto and San Bernardino, were originally 

 one mountain range formed by the intrusion of a granitic 

 molten magma and the uplifting of the intruded formations 

 we do not know. Both ranges have a core of intruded granite. 

 They are now separated by the great San Gorgonio Pass, a 

 sunken valley floor, with the San Andreas fault forming a break 

 in the crust of the earth by which California has been rent in 

 twain, and along which earth movements of tremendous geo- 

 logic significance have occurred, and may still occur. 



North and West of Los Angeles Is 

 the Santa Monica Range 



North and west of Los Angeles the Santa Monica Range lies 

 parallel with the Pacific Coast, which runs nearly due west. In 

 the distance to the east may be seen in the blue haze the outline 

 of the San Gabriel Range. At the western end of the San 

 Gabriel Range is Newhall Pass, and west of this is the Santa 

 Susanna Range. This last in turn joins the Santa Monica Range 

 still farther west, and northward extends the Coast Ranges. 

 North of the Santa Monica Range lies the San Fernando Valley, 

 a mountain basin having its outlet at Burbank, where the Los 

 Angeles River creeps through the mountains on its way to the 

 coast. Thus the Santa Monica Range is part of the complicated 

 system of mountain ranges which gives to Southern California 

 its remarkable topography. 



The Santa Monica Range is an arched ridge, technically 

 called an anticline, its axis parallel with the ocean coast. The 

 drainage of the southern slope is to the Pacific; that of the 

 northern to the San Fernando Valley. The slope on the north 

 as compared to that to the south is narrow. Streams flowing 

 toward the San Fernando Valley are generally not more than 

 one mile in length, whereas those draining to the ocean are as 

 much as seven miles in length. The fall to the San Fernando 

 Valley is much less than that to the Pacific. The streams have 



