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CALIFORNIA ACADEMY OF SCIENCES [Proc. 4th Ser. 



age. The beds at Oroville were laid down upon the Basement 

 Complex of the Sierra Nevada and the Chico. The so-called 

 lone formation, a local facies of the Tejon group which occurs 

 typically at lone and at Merced Falls, rests unconformably 

 upon the Mariposa slates and other members of the Basement 

 Complex. 



At the Oregon locality, however, a great thickness of ten 

 thousand feet of Tejon strata lies below the beds which yielded 

 the fauna described in this paper. The writer's previous con- 

 clusions from a study of the Siphonalia sutterensis fauna were 

 based upon stage of evolution, identity of a few species whose 

 ranges were limited to the uppermost beds in the Tejon in the 

 San Francisco Bay region, and the absence of many species 

 which were characteristic of the lower zones of the Tejon. 

 The recognition of the Siphonalia sutterensis fauna in Oregon 

 gives stratigraphic confirmation concerning the position of this 

 fauna in the Eocene time scale of the Pacific Coast; i. e., the 

 Siphonalia sutterensis Zone is the youngest Eocene thus far 

 recognized on the Pacific Coast. 



STRATIGRAPHY. 



The stratigraphic relations at the two collection points are 

 described by Martin as follows : "The beds at locality 24 dip 

 east at a low angle. The strike is nearly north and south. The 

 rock at this locality is a massive, blue-gray sandstone overlaid 

 by shale." At locality 25, Martin observed a dip of 20° East 

 and a strike of North 10° East. 



Mr. Diller, in the Roseburg Folio, describes this section as 

 follows : "The Umpqua is by far the thickest formation in the 

 Roseburg Quadrangle, but, on account of the lack of good ex- 

 posures of certain members of the series, the whole could not be 

 accurately measured. The best outcrops are along the Little 

 River, where a continuous section of a portion of the series is 

 well exposed. This portion has a thickness of about 7500 

 feet. It is interrupted on the northwest by the large mass of 

 diabase, beyond which, as shown in Section B, about 4500 feet 

 of still lower beds are seen, making a total thickness of approxi- 

 mately 12,000 feet for the entire exposed formation. It in- 

 creases in thickness to the northwest and has wide distribution 

 throughout the Coast Range." Diller's Section B places the 

 localities described above about 2000 feet below the top of the 

 Tejon. 



