SCIENTIFIC BACKGROUND 181 



GENERALIZATIONS CONCERNING THE BELT 



The country enclosed between the San Andreas and 

 the Puente Rifts constitutes a belt thirty miles in 

 width. Collectively this is a part of the great warp or 

 buckle in the continental trend, to be described on a 

 later page, which also produced the Transverse and 

 Ventura Ranges. 



The west end of the San Gebrial portion of the San 

 Andreas-Puente Belt of faulted structures bends north- 

 westward into an apparent continuation with the San 

 Rafael member of the Coast Ranges Belt, and its east 

 end as indicated by the San Jacinto and Elsinore Rifts 

 curves into the so-called Perris portion of the Pen- 

 insula Highland, thus making the semblance of a rib- 

 bon of nearly continuous supplementary highland about 

 twenty-five miles wide, which includes the San Rafael, 

 the San Gabriel Ranges, and some parts of the 

 Peninsula Ranges. These may serve as a kind of a 

 guide line in estimating the broader flexuring of the 

 region as a whole. 



It is also an interesting fact that the course of some 

 faults and flexured Ventura Ranges of the south side of 

 the belt, if projected southeastward, would be in con- 

 tinuation with both the trends of the southwest block 

 of the San Gabriel Highland, between the San Gabriel 

 and Sierra Madre Faults and the Pacoima-Verdugo 

 Ranges. 



The complicated details and relations of the western 

 end of the San Andreas-Puente Belt are not sufficiently 

 known to warrant positive assertions concerning them. 

 Some members of the belt bend northward into the 

 Coast Range trends and others strike towards the more 



