70 University of California Publications in Geology [VOL. 8 



places the one occurs without the other. They are associated at 

 Lower Lake in Lake County, but no Martinez occurs at the Marys- 

 ville Buttes in Colusa County where uppermost Tejon is found. The 

 Tejon of Merced Falls rests directly upon rocks of Jurassic age. Both 

 are found at Benicia, Martinez, and north of Mount Diablo, but on 

 the south side of Mount Diablo, the Tejon for the most part rests 

 directly upon the Chico. At San Pedro Point, San Mateo County, 

 Martinez without Tejon is found. At the type locality of the Tejon 

 on the Canada de las Uvas the upper Eocene rests upon the basement 

 complex of the Tehachapi Mountains, and no Martinez appears to be 

 present at the southern end of the San Joaquin Valley. However, 

 Martinez does occur on the seaward side of the ranges along the coast 

 thirty miles south of this same latitude in the Calabasas Quadrangle. 

 The Tejon at San Diego overlies the Chico. Fairbanks 10 mapped no 

 Eocene in the San Luis Quadrangle. South of this quadrangle great 

 thicknesses of Eocene strata were reported by Eldridge and Arnold 17 

 in the Santa Clara Valley. These beds were called the Topatopa 

 formation. No attempt was made to differentiate the upper and lower 

 portions of the "formation." 



At least three marked epirogenic movements occurred during 

 Eocene time: (1) a subsidence of the coast during which the Martinez 

 sediments were deposited, (2) an uplift during which large portions 

 of Martinez sediments were removed, (3) a subsidence during which 

 the Tejon sediments were deposited. That the sea during the first 

 subsidence did not extend so far inland as during the second appears 

 to be true, and deposition by a transgressing sea might account for 

 the occurrence of Tejon at Merced Falls and the Marysville Buttes 

 unassociated with Martinez if it were not for a widespread uncon- 

 formity between these two groups. Tejon sediments 2600 feet thick 

 south of Mount Diablo rest unconformably upon Chico, whereas at 

 least 700 feet of Martinez is found between the groups north of the 

 mountain. Unconformity between the two groups and a more widely 

 spread sea during Tejon time account for the difference in distribution 

 of the Martinez and Tejon in California. 



16 Fairbanks, H. W., San Luis Folio, no. 101, U. S. Geological Survey, p. 3, 

 1904. 



i? Eldridge, G. H., and Arnold, E., The Santa Clara Valley, Puente Hills and 

 Los Angeles Oil District, Southern California, Bull. no. 309, U. S. Geological 

 Survey, pp. 5-7, 1907. 



