19161 



Diekerson: Tejon Eocene of California 



389 



Bidwell Bar Folio, just east of this area. Oroville South Table 

 Mountain is about thirty miles northeast of the Marysville Buttes, 

 which are located in the center of the Sacramento Valley. 



Historical 



The region north of Oroville has been described in several of the 

 reports of the California State Mining Bureau 43 in connection with 

 the extensive hydraulic mines of that locality. Diller 44 and 

 Turner 45 have "described portions of it and Lindgren, 46 in a recent 

 paper summarizing all the previous work, has given detailed 

 descriptions of several mines of this area and published a geological 

 map of a portion of the Chieo Quadrangle. In this paper, the strata 

 beneath the Older Basalt of South Table Mountain are mapped as 

 lone. 



The first determinative fossils found in the sedimentary beds 

 beneath the Older Basalt were obtained by Mr. 0. W. Jasper, a 

 mining engineer, who sent a collection of marine fossils to the Uni- 

 versity of California from Oroville about fifteen years ago. He 

 described the locality as follows : "The collection of fossils referred 

 to were taken from a mine, . . . located at the south end 

 of South Table Mountain about two miles northeasterly from 

 Oroville. The tunnel from which the collection came was in about 

 2000 feet under the mountain." This collection contained Veneri- 

 cardia planicosta merriami, Barbatia morsel, and two new species 

 which have since been found in the Eocene at the Marysville Buttes 

 and described as Turrit ella merriami and Siphonalia sutterensis. 

 Mr. Harold Hannibal collected fossils from the strata beneath the 

 Older Basalt in the spring of 1913. Mr. J. H. Ruckman and the 

 writer visited Oroville South Table Mountain in November, 1913, 

 made a brief study of the stratigraphy and collected fossils from 

 several localities. Professor J. P. Smith in 1909 in a short paper, 

 "Salient Events in the Geological History of California", published 



43 Preston, E. B., Eleventh Annual Report, California State Mining Bu- 

 reau, p. 155, 1895. 



44 Diller, J. S., Tertiary Revolution in the topography of the Pacific 

 Coast, Fourteenth Annual Report, U. S. Geological Survey, pt. 2, p. 418, 1894. 



45 Turner, H. W., The Rocks of the Sierra Nevada, Fourteenth Annual 

 Report, U. S. Geological Survey, pt. 2, p. 463, 1894; Further contribution to 

 the geology of the Sierra Nevada, Seventeenth Annual Report, U. S. Geo- 

 logical Survey, pt. 1, p. 541, 1896. 



40 Lindgren, W., Tertiary Gravels of the Sierra Nevada of California, 

 Professional Paper 73, U. S. Geol. Survey, pp. 86-90, 1911. 



