438 DILLER AND STANTON — THE SHASTA-CHICO SERIES. 



fauna at its typical localities may be correlated with the lower Claiborne 

 fauna of the Gulf states. This is not the oldest Eocene fauna, as it 

 occurs in Alabama about 1,200 feet above the base of the Eocene. On 

 the other hand, the Chico fauna as typically developed in the Sacra- 

 mento valley does not indicate the latest Cretaceous time, so that a con- 

 siderable time interval is suggested by the paleontologic evidence. The 

 evidence of the reported commingling of the Chico and Tejon faunas has 

 been obtained "in the neighborhood of mount Diablo and northward, 

 where the strata are much dislocated and folded and the true strati- 

 graphic succession often obscured. 



The Chico, Horsetown and Knoxville beds have been found to grade 

 into one another in such a way as to show that they are simply different 

 phases of one continuous series of deposits extending without an im- 

 portant interruption of any kind from the bottom of the Knoxville to 

 the top of the Chico. For this set of beds the term Shasta-Chico series 

 has been proposed.^^ 



Sections of the Series. 

 elder creek section. 



The thickest section of this series that has yet been measured, and in 

 fact the thickest section yet knoAvn, is well exposed on Elder creek, 

 in Tehama county, California, where the Knoxville beds have an 

 apparent thickness of 20,000 feet, the Horsetown beds approximately 

 6,000 feet, and the Chico beds 4,000 feet, so that the total thickness of 

 the Cretaceous section in that region appears to be 30,000 feet.f 



In the accompanying table the section is given in some detail, includ- 

 ing the fossils which occur at different horizons. J 



*Bull. Geol. Soe. Am., vol. 4, pp. 205-224, and 24.5-256. Since the papers referred to were written 

 we have spent several months in the fi3ld, completeiy reviewing the Cretaceous of northern Cali- 

 fornia. The results fully confirm our previous views. 



fThis enormous thickness seems incredible, and yet, after going over the section several times, 

 we have not been able to find reliable evidence for its reduction. No duplication of strata could 

 be recognized either upon iithologic or paleontologic grounds, but, on the contrary, there seems 

 to be a regular succession without repetition in both rocks and fossils from top to bottom. The 

 evidence, however, is not strong, for in the Knoxville beds, which comprise the greater portion of 

 the series, there are few if any distinct Iithologic horizons bj' which repetition could be certainly 

 recognized, and very few fossils were found in them along the line of the section. Small folds and 

 faults, both normal and thrust, were observed so related to the dip of the strata as in some cases to 

 increase and in others diminish the thickness of the section. The etfeet of the one, as nearly as 

 could be estimated, counterbalanced the other. It is important to note in this connection that the 

 complete series of Shasta-Chico beds is not exposed in this section. At the eastern end of the 

 section the Chico beds disappear unconformably beneath the later deposits of the Sacramento 

 valley, which covers its topmost layers. The western end of the section is terminated by serpen- 

 tine which is probably of later eruption. 



I This section was measured in 1889 oy J S. Diiler and J. Stanley-Brown. Am. Jour Sci , vol. xl, 

 p. 476. 

 •\ 



