1 



1912] Clark: Neocene Section at Kirker Pass 49 



of Mount Diablo, listing forty-six species of marine invertebrates 

 from the beds on the north side of the mountain. 



Both Whitney and Turner stated that there was apparently 

 a conformable sequence of formations from the top of the moun- 

 tain down, including Cretaceous, Eocene, Miocene, and Pliocene. 

 Since these papers were published, unconformities have been 

 reported between the Franciscan and the Knoxville, the Chico 

 and the Martinez, and the Martinez and the Tejon. 5 



Monterey 



Relation to Tejon. — The Monterey series forms the basal 

 member of the Neocene on the north side of Mount Diablo. 

 Between unquestionable Monterey and Tejon it has not as yet 

 been possible to draw a sharp line in this section. 



A series of light brown to gray, micaceous, medium-coarse, 

 massive sandstones about 2000 feet in thickness which underlie 

 the clearly recognized Monterey is possibly the upward con- 

 tinuation of the Tejon, but so far no invertebrate fossils have 

 been found in them. Carbonaceous material, including leaves 

 and wood, is abundant in the upper part of this formation, and it 

 may be possible in the future to get good leaf collections that 

 will throw some light on the question of the age of these beds. 

 This zone is doubtfully referred to the Tejon but intensive col- 

 lecting will be necessary before its age can be certainly deter- 

 mined. 



Shale Member. — Above the micaceous sandstones just de- 

 scribed, and having the same dip and strike, appears a series 

 of shales, 150 to 200 feet in thickness, which quite certainly 

 represents the Monterey. The lowest member of this series is a 

 layer of white to light buff, diatomaceous shale, which in some 

 localities contains considerable lenses of limestone. Just what 

 relation these shales have to the micaceous sandstones below is 

 not clear. 



The Monterey shale of this section is in some localities thin- 

 bedded and slightly cherty. In other places it appears as a 



Diekerson, E. E., Univ. Calif. Publ. Bull. Dept. Geol., vol. 6, no. 8. 

 pp. 174-176, 1911. 



