50 SOUTHERN CALIFORNIA GEOLOGY 



earthquakes have taken place in the years of 1769, 

 1812, 1857, and 1906, which were 43, 45, and 49 

 years apart respectively, or an average of about 46 

 years. But there is no proof that the shakes mentioned 

 were the most severe. The two or three similar in- 

 stances may have been the merest coincidences. 



The wide divergence of opinion exhibited by these 

 estimates only tend to confirm one of the main theses 

 of this paper, that too little study has been made and 

 too little is known of the history of earthquakes in 

 Southern California to form conclusions on the sub- 

 ject of periodicity. 



FOREBODINGS NOT SHARED BY MOST 

 GEOLOGISTS 



Fortunately, the opinions of Dr. Willis are not shared 

 by many geologists and many of the best are on record 

 in writing as distinctly of the contrary opinion. In 

 fact I know of no one who is fully in accord with him, 

 and even a few who were at first inclined to follow 

 him will recant when they read the proofs of the error 

 of his ideas which are given on a later page. Gilbert, 

 Branner, Lawson, Arnold and others on record stated 

 that no such disasters as suggested need be anticipated 

 nor can be predicted. Over a hundred geologists of 

 high standing live in Southern California, who go about 

 their business without fear or anticipation of dis- 

 aster, many of them in homes built quite near or on 

 the fault lines. Of two chief students of the allegedly 

 dangerous San Andreas rift in Southern California, 

 one lives almost directly on it and the other has con- 

 structed a beautiful mansion near the Verdugo fault 

 line. 



