21B QUICKSILVER DEPOSITS OF THE PACIFIC SLOPE. 



view.' Gabb" vigorously maintained the Cretaceous age of tlie Tejon in 

 liis contributions to the State geological reports and elsewhere Prof. J. D. 

 Dana considers the Tejon as probably Lower Eocene and gives a list of 

 the Tejon genera to show the Tertiary character of the fauna.^ Prof Jules 

 ilnrcou asserts the Tertiary character of botli tlie Chico and the Tijon on 

 ^ paleontological and apparently on lithological grounds.* Prof. Angelo Heil- 

 prin, who has charge of Clabb's types, has ably reviewed the Tejon ques- 

 tion and pronounces emphatically for its Eocene age ^ Finally, Dr White 

 has examined many of the principal localities in the field and the collec- 

 tions made by my party, as well as Gabb's types. His conclusion, as al- 

 ready stated, is that the Chico is distinctly Cretaceous and the Tejon dis- 

 tinctly Eocene, but that the two form an unbroken series with a gradual 

 faunal change. 



At the time of the principal controvei'sy on the suliject of the age of 

 the Tejon the doctrine of evolution had not permeated science. It is now 

 generally accepted that transitions must exist between the faunal groups 

 or the geological periods which have received distinct names, and that the 

 divisions actually adopted were determined by the local conditions of those 

 regions in which geology was first studied. Twenty years ago the influ- 

 ence- of earlier views was still very strong, cases of transition were accepted 

 with reluctance, and few doubted that any series of beds exhibiting internal 

 evidence of continuity of life and sedimentation must be referred to a sin- 

 gle one of the standard series of formations, however remote the occurrence 

 might be from the typical localities of western Europe. This feeling was par- 

 ticularly- strong with reference to the Cretaceous and the Tertiary, between 

 which, as everyone knows, there is a peculiarly sharp break, both in Eu- 

 rope and in the eastern United States. It was not inmatural therefore that 

 Gabb should deny with as much emphasis as italics are capable of giving 

 that the case in hand was one of transition or that Conrad should resort 



' Am. Jour. Conchol., vol. 1, 1865, ji. 3G-2: ibid., vol. 2, 185G, p, 97; Am. Jour. Sci., 2d series, vol. 

 44, 1867, p. 376. 



=Am. Jour. Coucbol., vol. 2, 18C6, p. 87; Am. Jour. Sci., 2d scries, vol. 44, 1867, p. 226; Proc. 

 California Aiad. Nat. Sci., vol. 3, 1868, p. 301. The last is the most elaljorate. 



'Mauiial of Geology, pp. 457, 4.58, 491, 508. 



<Rept. Chief Eng. V. S. A., 1876, p. 387; Bull. Soc. g^ologique France, vol. 2, 1883, p. 407. 



'^Proc. Phila. Acad. Sci., 18h2, p. 195; Contributious to the Tertiary Geology and Paleontology of 

 the United States, 1884, p. 102. 



