I 916 ] Dickerson: Tejon Eocene of California 461 



to low dips of the lone of the north Sacramento Valley. Evidently 

 folding and faulting in post-lone time in the Coast Ranges has been 

 quite vigorous in contrast to the slight changes in the Klamath 

 Province. 



As will be shown later, the physiographic provinces of California 

 were inaugurated in Eocene time and a part of the diastrophic move- 

 ments which have determined these provinces actually took place dur- 

 ing the Eocene. 



Diller 79 recognized the lone formation on the west side of the 

 Sacramento Valley in the vicinity of the Cold Fork of Cottonwood 

 Creek, Tehama County. 



On Cold Fork, however, only a few miles further north, the exposures 

 are good and thirty feet of the lone formation was seen. It is composed 

 chiefly of yellow gravel, but is separated from the overlying tuff by a 

 stratum of clay about a foot in thickness. Here the lone formation ends 

 abruptly against a steep slope of the Cretaceous strata upon the edge of 

 the base level of erosion, but the overlying tuff and Red Bluff formation 

 lap over upon the base level, showing that they are of later origin. 



On Salt Creek, about six miles north of Cold Fork, the lone forma- 

 tion has the largest exposure seen on the western side of the Sacramento 

 Valley. Immediately beneath the tuff there is sixteen feet of clay, which 

 is underlain by forty-eight feet of sand and gravel beds, making a total 

 thickness of sixty-four feet exposed. The gravel predominates and the 

 pebbles increase in size toward the base. Similar sections are seen in 

 Dry Creek, Roaring River, and the North Fork of Cottonwood Creek. 

 In every case the bed lying immediately beneath the tuff is a layer of clay. 

 This top bed of clay extends further westward upon the edge of the 

 base level than any of the other beds, and the whole formation rapidly in- 

 creases in thickness toward the Sacramento Valley. In some cases the 

 tuff and gravels of the Red Bluff formation lap over upon the base level 

 plain for several miles, but the lone formation stops at its edge. 



Judging from Diller 's description, the shore line of the Eocene 

 sea was marked by these deposits along the edge of the Klamath 

 peneplain. The occurrence of marine lone at Oroville and at Marys- 

 ville Buttes has been described in detail above. It seems probable 

 that there was not an extensive land-mass west of the Marysville 

 Buttes, as the Eocene deposits in this vicinity were laid down in 

 water about one hundred fathoms in depth along the edge of the 

 continental shelf, as is evidenced by the abundance of glauconite and 

 by certain deep-water facies exhibited by the fauna. 



South from Oroville unmistakable strand-line conditions have 

 been recognized at lone, Merced Falls and Bear Creek, Merced 



70 Diller, J. S., Topographic Revolution on the Pacific Coast, Fourteenth 

 Annual Report U. S. Geological Survey, p. 455, 1894. 



