206 G. F. BECKER — EARLY CRETACEOUS OF CALIFORNIA. 



More recent collections in British Columbia show that five of the species 

 found in the Aueella-heariug beds there are common to these deposits and to 

 the subdivision C of Queen Charlotte's islands. 



Conclusions on the Shasta Group. — The conditions and associations on the 

 British Pacific coast thus appear to correspond completely with those in the 

 United States so far as the Aucella beds are concerned, and the present indi- 

 cations are that all of them are to be regarded as equivalent to the Gault. 

 Of course this reference is liable to fresh emendation as researches are fur- 

 ther prosecuted, but in the meantime Gabb's name, the Shasta group, is the 

 proper designation of the series. 



The post-Jurassic upheaval of Professor Whitney, which became post- 

 Neocomian in my former papers, now becomes post-Gault. 



The Post-Triassic Upheaval. 



The non-conformity at Horsetown preceded the earliest known Cretaceous 

 of the Pacific slope. The corresponding disturbance was certainl}^ later 

 than the Carboniferous. There is also evidence that it was later than the 

 Trias. At the head of Kaweah river, in the Mineral King district, about 

 two miles from the summit of the western branch of the Sierra, a large mass 

 of slate is included in the eruptive granite. The slates are vertical and 

 very nmch metamorphosed, but at one point they show casts of shells. I 

 brought in a considerable quantity of these remains, which have been exam- 

 ined by Dr. White and Mr. C. D. Walcott. They were unable to identify 

 the fauna with any other yet discovered, but they pronounce it distinctly 

 Triassic. 



The main mass of the granite of the Sierra is earlier than the Aucella beds 

 and in part at least later than these Triassic beds. It is very probable that 

 a granitic extrusion accompanied the disturbance which led to the non-con- 

 formity at Horsetown. In British Columbia Dr. Dawson has traced a post- 

 Triassic upheaval which was accompanied by granites.* This seems to add 

 one more to the many indications that the Pacific coast throughout North 

 America, if not throughout the two Americas, has had a very similar 

 history. 



Washington, D. C, December, 1890. 



* Trans. Roy. Soc. Can., Vol. 8, part IV, 1890, p. 6. 



