COXOLUSIONS. 257 



It has been shown by J. S. Diller''^ and T. W. Stanton that there is no 

 break between the Shasta and the Chico oronps ; therefore any meta- 

 morphisni that affected the Knoxville ought to have affected the Chico 

 also ; but this is nowhere the case. ]\Ir Diller has further shown that 

 the uplift and metamorphism was pre-Cretaceous in the Klamath moun- 

 tains and in the northern Sierra Nevada. 



H. W. Turner t assumes that the metamorphic series of mount Diablo 

 pass over into the unaltered Knoxville, but without any convincing 

 proof, as he afterwards admits.;]: 



H. W. Fairbanks § says that he has traced the phthanites of the 

 Klamath mountains into those of the Coast range, and throughout both 

 these mountain chains has found the Knoxville beds, when present, resting 

 everywhere unconformably on this metamorphic core of pre-Cretaceous 

 rocks. All these writers agreed that ii Aucella could be found in the 

 metamorphic series, its Cretaceous age would be settled. 



But from what has ])een said as to the age of Aucella-bearing beds in 

 Europe it becomes plain that such is not the case. In 1892 the writer 

 found in the metamorphic phthanite series of Alum Rock canyon near 

 San Jose several aucella? of the tj-pe A. mosquensis, Buch, as figured by 

 Lahusen; || also in Stevens creek canyon, about 18 miles west of Moun- 

 tain View, Santa Clara county, he found in very silicious, black meta- 

 morphic shale aucella? that agree with Aucella trigonoides^ Lahusen. 



Now these two species of Aucella in Russia are confined to the middle 

 and up})er Portland, of the Upper Jura. It is therefore probable that at 

 least a part of the Coast range metamorphics are of Upper Jurassic age. 



A. C. Lawson^" accepts the pre-Cretaceous age of the Coast range meta- 

 morphics, but thinks the uplift was pre-Jurassic and that the erosion 

 took place during the Jura. 



From what has been said it is seen that the uplift and metamori:)hism 

 was of late Jurassic age in at least a portion of the Coast range. 



Conclusions. 



The Auriferous slates are known to consist of Silurian, Carboniferous, 

 Triassic and Jurassic strata. 

 ^ Tlie Mariposa slates are of Up]ier Jurassic, probal)ly lower Kimme- 

 ridge, age. 



♦Bull. Geol. Soo. Am., vol. 4, pp. 205-224 and pp. 245-256. 



t Bull. Geol. Soc. Am., vol. 2, p. 394. 



X Am. Geologist, vol. xi, 1893, p. 314. 



g Am. Geologist, March, 1892, and February, 1893. 



H M6m. Com. Geol. Russia, vol. viii, no. i, p. 30, pi. 11, figs. 21-24. 



^ Jour. Geology, vol. i, p. 583, 'The Cordilleran Mesozoic Revolution.' 



