30 SOUTHERN CALIFORNIA GEOLOGY 



The San Andreas line of maximum seismicity ex- 

 tends close to and into the border of the sea in North- 

 ern California, especially near the cities of San Fran- 

 cisco and Palo Alto, where Dr. Willis' residence and 

 experiences have been. 



In Southern California the San Andreas and San 

 Jacinto rift-lines lie from fifty to two hundred miles 

 inland and pass for the most part through thinly settled 

 regions. I believe that all analyses and comparisons 

 that can be made between these conditions in the two 

 regions will prove immensely favorable to Los Angeles. 

 DIFFERENCES IN MATERIAL 



The many points of differences of detail between the 

 geologic material and structure of Southern and North- 

 ern California have great bearing upon the question of 

 earthquakes and, when considered, will be found to be 

 of great importance. 



Dr. Ralph Arnold has recently called attention to 

 these differences in a telegram to the Los Angeles 

 Chamber of Commerce which we use by his consent. 

 It is as follows : 



*T believe persistent rumors that Los Angeles is due 

 for disastrous earthquake are absolutely unfounded. 

 Those scientists who are apparently taking this view 

 have less practical field knowledge of conditions in 

 Southern California than I have. Our greatest menace 

 in California from earthquakes is through the San 

 Anderas rift. This is at least 40 miles north of Los An- 

 geles, separated from it by great buffer range of gran- 

 ite mountains. Our quakes result from movements 

 along local faults which, being in soft Tertiary beds, 

 reach a breaking point with much smaller stress than 

 along San Andreas Rift, hence we may expect earth- 



