446 DILLEE AND STANTON TPIE SHASTA-CHICO SERIES. 



Ammonites (Desmoceras) hreweri and many species of other classes of niol- 

 lusca that are associated with them in both California and Queen Char- 

 lotte islands, show that at least a part of the lower shales or division C 

 of the Queen Charlotte Cretaceous may be correlated with the extreme 

 upper portion of the Horsetown beds, if not with the base of the Chico. 

 They also show indirectly that the upper part of the Queen Charlotte 

 formation and the Vancouver formation must be closely related, since 

 the latter holds the same fauna as the typical Chico ; that is, the Van- 

 couver fauna should immediately succeed the latest portion of the Queen 

 Charlotte fauna, instead of being separated by the time interval required 

 for the deposition of the 3,500 feet of strata in divisions A and B of the 

 Queen Charlotte islands section. 



Three of the ammonites above mentioned and a number of other spe- 

 cies are represented by identical or closely related forms in the Ootatoor 

 group of India, which is usually correlated with the European Ceno- 

 manian, and a similar fauna is found in the Cretaceous of Japan and 

 Saghalin. These forms indicate that in Cretaceous time the faunas of 

 the Pacific were able to migrate from one side of the ocean to the other, 

 probably through the shallow waters of high northern latitudes, and 

 thence along the shores on either side. 



Loiuer Horsetown. — The lower Horsetown beds are characterized by a 

 greater abundance and variety of ammonites with a smaller proportion 

 of other moUusca, though in the occasional sandstone beds that occur in 

 the shales down to the base the fossils are more closely related to the 

 littoral faunas of the upper Horsetown and Chico, and several of the 

 species seem to range through the entire division. There is certainly no 

 faunal break within it. This portion of the Horsetown also is repre- 

 sented at many localities in the lower shales of Queen Charlotte islands. 



The exposures below the Chico in the Elder Creek section have not 

 yielded many fossils, but in the Bald hills, two to four miles south of 

 Elder creek, several fossiliferous localities were found, both in the Horse- 

 town and in the Knoxville beds. 



At one of these localities near Wilcox's ranch a zone at the base of the 

 Horsetown, not more than from 50 to 200 feet above the Aucella beds, 

 yielded ma.ny species that are characteristic of the lower 1,500 feet of the 

 Cottonwood Creek section. They include — 



Pecten opercuUformls, Gabb. Amm. {Lytoceras) batesi, Trask. 



Plicatula variata, Gabb. Amm. {Phylloceras ?) ramosus, Meek. 



Nemodon Vancouver ensis, Meek. Amm. (Olcostephanus) traski, Gabb. 



Pleuromya Ixvigata, Whiteaves. Amm. {Olcostephanus), sp. a. 



Potamidcs dladema, Gabb. Crioceras percostatus, Gabb. 



Helicaulax bicarinata, Gabb. Crioceras latus, Gabb. 



Actaeon impressus, Gabb. Belemnites impressus, Gabb. 

 Lunatia avellana, Gabb. 



