120 SOUTHERN CALIFORNIA GEOLOGY 



sition opposite the northeast end of the San Gabriel 

 Plateau, If true, such a movement, of course, in- 

 volved a vast length of time. Misconceptions concern- 

 ing alleged movements of this kind in recent years 

 have caused the confusion concerning earthquake pre- 

 diction. 



A great horizontal "buckle," complicated by thrust 

 faulting, which apparently extends through the apex 

 of the arched trends of the Ventura group of flexured 

 ranges, may also be a result of regional, horizontal 

 drifting. 



A compressive thrust-fault of fair proportions has 

 been pointed out by Kew^ as existing along the north 

 side of San Cayetano Mountain and the south side of 

 a portion of Oak Ridge. Another of local character 

 is cited by Noble on the north side of the San Gabriel 

 Range, where the granite is pushed over the later sedi- 

 mentaries of the desert border. Recently a great over- 

 thrust of some thirty miles has been reported from 

 near Las Vegas, Nevada, by Hewitt and Longwell." 



RATE OF MOVEMENT 



Various wild guesses have been made as to the 

 present-day rate of movement along the San Andreas 

 rift. It has even been estimated at as much as 

 one and one-quarter miles in eighteen years. The 

 Coast Survey studies previously mentioned estimated 

 that Gaviota Peak had moved twenty-four feet north- 

 ward in thirty years. To tell the truth, no quantitative 

 estimates! are as yet reliable. 



At the present moment it appears that no observable 



'U. S. Geol. Survey Bull., No. 753, p. 100, and map. 

 -Bull., Geological Society of America, 1927. 



