1916] 



Packard: Cretaceous of Santa Ana Mountains 



151 



The apparent conformable secpience of beds of the Shasta-Chico 

 series as exposed on Elder and Cottonwood Creeks in Tehama and 

 Shasta counties, together with the recognized faunal continuity make 

 the definition of the different groups difficult. Diller and Stanton 

 who have most carefully considered this question make the following 

 statement: "The faunas of adjacent beds, however, are so bound 

 together by many common species that there is no palaeontologic 

 break anywhere within the series." 10 



The Knoxville may for the purposes of this paper be defined in 

 the words of Stanton as "the Aucella-bearing Cretaceous beds on the 

 Pacific Coast of the United States." 17 No specimens of Aucella have 

 been reported from the Santa Ana region and therefore this phase of 

 the Cretaceous need not be discussed further. 



The Horsetown was first defined in a paper by Charles A. White 

 entitled "Notes on the Mesozoic and Cenozoic Palaeontology of Cali- 

 fornia." 18 On page 19 of this paper he writes: 



I shall therefore, for the present, retain the name Shasta group in the 

 general sense in which it was used by the geologists of the California survey; 

 but for purposes of convenience in references which I must necessarily make 

 in this article to those divisions, I shall designate them as the Horsetown beds 

 and the Knoxville beds, respectively. These names are suggested by the 

 localities from which the best collections of fossils of each division were 

 obtained. 



On the next page he states regarding the fauna: "It is especially 

 rich in Cephalopoda, as will appear by referring to the California 

 reports, where the fossils of this division are recorded as coming from 

 "The North Pork of Cottonwood Creek, Horsetown, etc." A few 

 sentences below this White lists thirteen of Gabbs' species which he 

 would exclude from the Horsetown because of their occurrence at 

 doubtful Horsetown localities. Five of these, Potomides diadema 

 Gabb, Ringinella polita Gabb, Liocium punctatum Gabb and Lima 

 shastaensis Gabb are later reported by Anderson 10 from the Horsetown, 

 although their occurrence is not definitely given. It thus appears that 

 the type section of the Horsetown beds includes beds of the Shasta 



i« Diller, J. S. and Stanton, T. W., The Shasta-Chico Series, Bull. Geol. Soc. 

 Am., vol. 5, p. 464, 1894. 



" Stanton, T W., The Fauna of the Knoxville beds, U. S. Geol. Surv. Bull. 

 133, p. 12, 1895. 



is White, C. A., U. S. Geol. Surv. Bull. 15, pp. 19-20, 1885. 



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

 Acad. Sei., Third Series, Geol., vol. 2, p. 41, 1902. 



