152 SOUTHERN CALIFORNIA GEOLOGY 



other directions mentioned. Such has been the case 

 along the south sides of the San Gabriel and Puente 

 Ranges, where the northeast structures have been cut 

 across by the Cucamonga and Puente faults respective- 

 ly. At present I have no idea as to the initial age of 

 this type of faulting. Its presence in the highlands and 

 absence in the plains suggests that it is relatively old ; 

 apparently older than the east-west group and many 

 of the northwest faults. 



THE SECOND BELT OF NORTHWESTERLY 

 FAULTS 



The next structure belt to be described consists of 

 many master faults mostly of remarkable length, con- 

 tinuity and rectilinearity, of which the Cadiz, San 

 Jacinto, and Elsinore rifts are examples. Like those of 

 the first described northwest extending belt (in which 

 I arbitrarily included the Catalina and Coast Range 

 groups) and from which the members of this group 

 are only doubtfully separated, they have northwest- 

 southeasterly directions. In fact I make no definite 

 assertion that the two groups are separated from each 

 other. 



The master rifts of this belt occur parallel to one 

 another at intervals of from five to twenty miles 

 in the wide country between the Colorado River just 

 north of Blythe, on the east, and the San Diego County 

 coastal border on the west. They parallel the sup- 

 posed faults of the submerged Catalina trends which 

 have been arbitrarily placed in first northwest trending 

 group, but which might equally as well be placed with 

 this second group. The total width of the belt in Cali- 

 fornia is about two hundred miles. It is difficult at 

 present to assign it a definite length, for only a portion 



