THE ECOENE. 299 



detail and would bear enlargement to three tinies the scale on which it is 

 published. 



Eocene. — Tlie Tcjou fomiatiou is also represented at New Idria. Fossils 

 were found in it by Mr. Gabb, and my party also collected a numlier of 

 characteristic forms. For the reasons set forth in Chapter V it has been 

 for many years a mooted point whetlier tlie Tljou series formed a portion 

 of the Cretaceous or of the Tertiary. The fact is that it may be said to 

 belong- to botli. Tiiere is neither fixult nor unconformity between the 

 Chico and the Ttjon at New Idria; the deposition of sands went on luiin- 

 terruptedly from the one period to the otlier, and Dr. White shows that 

 there was a continuity of life also between the two. In short, in California 

 there is no sharp distinction between the two series, though the Chico- 

 T^jon beds are divisible paleontologically into an upper and a lower portion 

 connected by transitions. The character of the faunas, however, proves 

 that the Chico must be regarded as the concluding period of the Creta- 

 ceous era and the Tejon as the opening period of the Tertiary. Such a 

 transition has been observed nowhere else in America or in Europe. 



Even if the strata at New Idria were more abundantly supplied witli 

 fossils than thev are, a hard and fast line could not be drawn between the 

 Chico and Tcjon. The demarkation indicated on the map, however, is not 

 wholly arbitrary. The beds containing distinctly Tcjon fossils botli here 

 and at Mt. Diablo differ physically from the Chico. The upper series is 

 composed almost exclusively of sandstones which are remarkably light 

 colored — often pure white — while the Chico sandstones are firmer and of 

 a tawny color. These characteristics are so persistent that I have drawn 

 the outline of the Tejon at the lowest of the white beds. The included area 

 of course embraces all the known localities at which fossils referable to 

 the upper series are found. 



The line drawn between the Chico and the Tejon is rather irregular 

 on the map and at its easterly end bends sharply northward. This suggests 

 a non-conformity, but the suggestion is misleading. A portion of the irreg- 

 ularity of the outline is due to the unevenness of the surface. At many 

 exposures the beds are shown in perfect conformity, but the soft, white 

 beds have yielded to the stress accompanying upheaval more than the great 



