has come to be the way it is the most complex, the most 

 varied, the most stupendously interesting, of all regions he has 

 ever visited. 



The author extends congratulations to the State of Califor- 

 nia and other western states for the splendid galaxy of scientific 

 students and investigators who have studied the problems of 

 geology in this western land, and who have so splendidly ex- 

 pressed in books and scientific journals the results of their 

 studies. Books and papers that have been consulted are named 

 in the bibliography at the end of this volume. Without these 

 great sources of information it would have been impossible to 

 complete the task that the volume undertakes. Students who 

 may wish to verify statements made, or further pursue the 

 subjects referred to may consult the bibliography, and in 

 libraries pursue the subject further. 



The author is personally indebted to representatives of Fed- 

 eral and State surveys, the University of California, Stanford 

 University, to the geologists of California and of other States, 

 whose works he has drawn upon. The kindly assistance and 

 co-operation that have been extended by officials of scientific 

 surveys, by authors, scientific journals and associations, and by 

 individual geologists, is highly appreciated. Credit is extended 

 in the bibliography, where these publications are listed. Illus- 

 trations which it is hoped will add clearness to the narrated 

 facts have been drawn from a wide range. 



To the James J. Hill Reference Library, of St. Paul, Minn., 

 the author is under deep obligation for the splendid facilities 

 offered by this institution. The vast assemblage of books, made 

 available by a trained and efficient staff, and use of a private 

 study room, have contributed immeasurably to the accomplish- 

 ment of the author's task, and his sincere thanks for and appre- 

 ciation of the courtesies extended are hereby expressed. 



D. E. W. 



San Clemente, California. 



