THE GEOLOGY OF THE SAN FRANCISCO 

 PENINSULA. 



The Coast Ranges of California embrace an extensive region 

 in which are presented complicated but exceedingly interesting 

 geologic problems. Much attention has been given to these 

 mountains for many years, but with the exception of a stud_y of 

 the quicksilver deposits, it is only recently that we have had 

 presented in a thorough manner the results of the detailed exami- 

 nation of local areas. 



Professor Lawson's recent report upon the geology of the 

 San Francisco Peninsula^ is perhaps the best yet made of any 

 local area in the Coast Ranges and illustrates well what modern 

 methods of research can accomplish in a complicated field. 

 Notwithstanding the excellencies of the report, there is an infe- 

 licity displayed in the discussion of several problems which is 

 regrettable in a study of this kind. This has, however, neces- 

 sarily resulted from the method pursued, in that the investigator 

 has given his attention almost exclusively to a narrow field of 

 complex geology and has failed to make use of the results of 

 the work of others, concerning questions which the phenomena in 

 that field did not illuminate. It is absolutely necessary for the 

 appreciation of many facts in any local area, and for the philo- 

 sophic discussion of the history of that area, that the student 

 should have a general knowledge of the relations existing over 

 the region as a whole. 



As a result of some experience in the Coast Ranges I feel called 

 upon in the interest of geological progress to express most 

 profound objections to a number of conclusions reached by 

 Professor Lawson concerning some of the vital questions involved 

 in the geological history of this region. Consequently in answer 

 to his frank request for friendly criticism, I will take up the dif- 



' U. S. Ge(jl. Sur., 15th Annual Report, pp. 405-476. 



63 



