7,4 H. W. FAIRBANKS — GEOLOGY OF THE COAST RANGES. 



Blake says : ^ 



"In California the term 'Coast mountains' is generally understood to refer to 

 the several ranges of mountains lying west of the Sierra Nevada, extending from 

 Oregon to point Conception, and forming the barrier between the long interior 

 valleys of the Sat^ramento and San Joaquin and the Pacific ocean." 



Professor Whitney f defines the Coast ranges as follows : 



"We consider all those chains or ranges of mountains to belong to the Coast 

 ranges which have been uplifted since the deposition of the Cretaceous formation ; 

 those, on the other hand, which were elevated before the epoch of the Cretaceous 

 are reckoned as belonging to the Sierra Nevada." 



He says further that between the parallels 35 and 40 degrees north lati- 

 tude there is no difficulty in separating the Coast ranges from the Sierra 

 Nevada, and that it is only on geological considerations that the lines 

 can be drawn ; that the topography gives no clue. On the north he con- 

 siders the Coast ranges terminated by the Klamath and Trinity rivers, 

 while on the south he would extend them to San Diego county, includ- 

 ing the San Gabriel and Santa Ana ranges. 



Jules Marcou J agrees with Dr Trask in that the Coast ranges should 

 be considered as terminating in the southern part of San Luis Obispo 

 county. 



In Bulletin 33 of the United States Geological Survey, J. S. Diller says: 



' ' For reasons hereafter given we will consider the northern end of the Sierra 

 Nevada range to be in the vicinity of the North fork of Feather river before reach- 

 ing Lassen's peak. From this point the elevation is continued for about fifty miles 

 on the trend of the Sierras in the Lassen's peak volcanic ridge, w^hich terminates 

 near Pitt river. All south and w^est of mount Shasta belong to the Coast range. 

 There appears to be a lack of appropriateness in including the ridges east of the 

 Sacramento river, about the headwaters of the McCloud, in the Coast range, but it 

 is evident that they are more closely related geologically to the Trinity and Scott 

 mountains of the Coast range than to any portion of the Sierra Nevada." 



He does not say whether it is used by him with the meaning simply 

 of a topographic province, though that is the implication. In a recent 

 note received from Mr Diller he emphasizes the statement that the term 

 is used by him to indicate simply a " topographic province." 



TEE A UTROB'S USE OF THE TERM COAST EANGES. 



From the foregoing quotations it will be seen how difficult it is to frame 

 an exact definition of the term Coast ranges. The definitions given vary 

 greatly, being based partly on age and partly on topography. Further 



* Ibid., vol. V, p. 138. 



t General Geology of California, p. 167. 



X Wheeler's Survey, 1876, p. 172. 



