work of whitney, le conte and others. 250 



Review of Literature. 



For the first accurate information as to the geologic character and 

 occurrence of the gravel beds we are mainly indebted to the former state 

 geological survey of California under Professor J. D. Whitney. His 

 volume on the Auriferous gravels * containing, besides his own extensive 

 observations, the detailed notes of W. A. Goodyear and Professor W. H. 

 Pettee, marks an epoch in the development of our knowledge of these 

 Neocene deposits. The observations recorded in this book are in general 

 accurate and trustworthy. The "review" at the end of the volume by 

 Goodyear appears, in the light of later investigations, as very excellent 

 indeed, and. while one may differ from some of his conclusions, it must 

 be acknowledged that his views of the channels and of the general 

 topography of the country over which they flowed are confirmed by 

 more detailed and extended surveys. To these investigators belongs 

 the credit of having established the fluviatile character and the age 

 of the deposits, of having recognized the two important river sys- 

 tems corresponding to the present Yuba and American rivers, and 

 of having begun to outline the old drainage lines. Professor Whitney 

 concludes that the Sierra Nevada has not undergone any important 

 changes as to the general level and the grade of its channels, and that 

 the carving of the canyons subsequently to the gravel period was prin- 

 cipally caused by climatic changes. 



In 1886 Professor Joseph Le Conte published a paper on "A post- 

 Tertiary elevation of the Sierra Nevada shown by the river beds," f in 

 which no new observations were recorded, but which gave an impetus to 

 the investigation by the introduction of a new theory, which, however, 

 had already been suggested by Mr G. K. Gilbert in 18834 In subse- 

 quent papers Professor Le Conte has further elaborated his views, § and 

 in 1891 he published a paper on the " Tertiary and post-Tertiary changes 

 of the Atlantic and Pacific coasts," || in which is found a concise state- 

 ment of his present opinion, which is quoted in full: 



"The Sierra was formed, as we now know, by lateral crushing ami strata-folding 

 at the end of the Jurassic. But during the long ages of the Cretaceous and Tertiary 

 this range was cut down to a very moderate height, with gentle slopes eastward 



*.I. D. Whitney: "The Auriferous Gravels of the Sierra Nevada of California." Memoirs of tin.' 

 Museum Comp. Zoo!., vol. <;, no. l, 1880. 

 t Am. .lour. Sei., 3d series, vol. xxxii, 1886, \>. 167. 

 {Review of Professor Whitney's "Climatic Changes;" Science, vol. i, 1883, pp. 141-142, 169-173, 



an. I 193-195. 



gForamore extended review of the literature regarding this subject the reader is referred to 

 Mr II. W. Turner's "Mohawk Lake Beds." Bull. Phil. Soc. Washington, vol ix, April, 1891, pp. 



385-410, 



II Bull. Geol. Soc. Am., vol. 'J, pp. 323-330. 



