138 University of California Publications in Geology [Vol. 9 



thirteen miles in length. The large fauna is divisible into three zones, 

 each of which has been designated by the name of a characteristic 

 species. This section may be regarded as a type region for reference 

 of faunal zones of the Chico group. 



The writer wishes to thank Professor John C. Merriam for his 

 interest in, and general supervision of, this study, and to acknowledge 

 the assistance given him in the field by Dr. Roy E. Dickerson and the 

 other members of the field party. 



Review op the Literature 



The first recognition of faunal differences in the Cretaceous of 

 California should be credited to W. M. Gabb, 1 who divided the Cretace- 

 ous into the Shasta and Chico groups on the basis of faunal differ- 

 ences. C. A. White 2 in 1885 divided the Shasta group of Gabb into 

 the Knoxville and Horsetown beds. The fauna obtained from AVhiteV 

 Wallala group, which was then thought to be intermediate in age 

 between that of the Horsetown and Chico, is now considered to be but 

 a phase of the lower Chico. 4 Dr. T. W. Stanton has studied the Cali- 

 fornia Cretaceous in its various aspects, and has contributed largely 

 to our knowledge of the different faunas. 



The classification of the California Cretaceous as given by White 

 remained unchanged until in 1902 P. M. Anderson divided the Knox- 

 ville into an upper, or Paskenta horizon, and a lower, less fossiliferous 

 one to which he applied the term Sub-Knoxville. 5 



Anderson recognized two faunal stages in the Chico, under the 

 names of Upper and Lower Chico. His conclusions were derived from 

 compiled and revised lists of species, which were, as he states, "massed 

 from a number of the more significant localities." 6 Regarding the 

 Horsetown and the Chico Anderson writes that "the transition of 

 faunas is more gradual than it has been in any other basin of the 

 Pacific border ; and for that reason the faunas representative of the 



1 Gabb, W. M., Palaeontology of California, vol. 2, p. xiii, 1869. 



2 White, C. A., On the Mesozoic and Cenozoic Palaeontology of California, 

 U. S. Geol. Surv. Bull. 15, p. 19, 1885. 



3 White, C. A., On new Cretaceous Fossils from California, U. S. Geol. Surv. 

 Bull. 22, 1885. 



i Willis, Bailey, Index to the Stratigraphy of North America, TJ. S. Geol. 

 Surv. Professional Paper 71, p. 647, 1912. 



■> Anderson, F. M., Cretaceous Deposits of the Pacific Coast, Proc. Calif. 

 Acad. Sci., Third Series, Geol. vol. 2, p. 47, 1902. 



e Op. cit., p. 25. 



