SCIENTIFIC BACKGROUND 169 



plain of granite and metamorphic rocks which extend 

 indefinitely southeastward, and that the valley areas 

 on the San Jacinto and Elsinore sides thereof are 

 graben-like troughs or sunken blocks. 



THE SAN ONOFRE FAULT 



Another master fault line which is of some magni- 

 tude, though relatively less conspicuous than some of 

 those mentioned, follows the tilted fault-block down 

 as the San Onofre Hills, in northeastern San Diego 

 County, as has been pointed out by Woodford.^ The 

 regional topography contains the suggestion that this 

 fault might be continued northward to the Santa Ana 

 River. 



THE INGLEWOOD FAULT 



A line of faulting follows the course of the Domin- 

 guez Range, Southern California's newest and greatest 

 wealth-producing mountain chain, from the south side 

 of the Santa Monica Mountains on the north, to and 

 beyond Balboa to the southeast. This fault closely fol- 

 lows the coast line in its extension southeast from Bal- 

 boa toward San Diego. 



This rift line consists of one or more closely-spaced 

 faults which usually follow the southwest side of 

 that portion of the chain southeast of Hawthorne. It 

 passes through the center of Inglewood Hill to the 

 northwest of Inglewood, where the course is marked 

 by a deep summit-valley and one or more parallels on 

 the east. The aggregate displacement of the main 

 fault in the Baldwin Hills is at least three hundred 

 feet to the west, as has been ascertained from oil well 

 logs. 



'Geological Bulletin, University of California, vol 15, No. 7. 1925. This 

 valuable paper contains instructive -lejcription of alternations of rising and 

 sinking of individual fault blocks. 



