THE COAST RANGES AND THE SIEKKA. 211 



tiou of California, though the results in the Coast Ranges may luive long 

 since been obliterated. On the other hand, the post-Knoxville disturbance 

 must have been felt at Pence's ranch, though its effects may have been 

 trifling as conii)ared with those of earlier convulsions. 



The Coast Ranges members of the western Cordillera system. As hclS alrCadv beCU Statcd, 



I am unable to see any reason for dissenting from Professor Whitney's 

 opinion tliat tiie fossiliferous beds of Mariposa form an integral portion of 

 the modern Sierra Nevada range. It seems simply impossible that they 

 should iiave assumed their present vertical position with a strike parallel 

 to the cre.st and tliat they should have been profoundh' modified by chem- 

 ical action, except under conditions of disturbance amply sufficient to bring 

 about essential modifications of the whole range. That there were at the 

 time, or at least had been, mountains in nearly the same position does 

 not impair the claim of this addition to be considered as much a part of 

 the modern Sierra as any older portion. If the conclusions thus far stated 

 be accepted, it follows at once that subsequently to the close of the 

 Knoxville, but long before the beginning of the Chico, both the Sierra 

 and the Coast Ranges experienced an upheaval. This was in all proba- 

 bility not the first along the line of the Sierra and very possibly did not 

 actually originate the Coast Ranges, but for the latter it is the first dis- 

 tinctly traceable movement. It is conceivable that within the limits of 

 time indicated two upheavals should have taken place, one affecting only 

 the Sierra, the other only the Coast Ranges; but the probability of this 

 alternative will scarcely be seriously maintained. The earlier determina- 

 ble portion of the Coast Ranges must therefore be considered as due to the 

 same disturbance which added the gold belt proper to the Sierra Nevada. 

 Ther.e is much probabilit}'' that a portion at least of the Cascade Range 

 was elevated and metamor|)hosed at the same time. Th-e relationship thus 

 established is brought out more clearly by a comparison of the history of 

 the ranges so far as it can be traced. 



Both the Sierra Nevada and the Coast Ranges were above water and 

 underwent erosion during the interval between the Knoxville and the 

 Chico epochs. Both ranges also sank just before the beginning of the 

 Chico, admitting the ocean over a great part of the Coast Ranges and over 



