92 University of California Publications in Geology [Vol. 8 



can be no doubt that practically the same horizon is represented at all three 

 places. Chico species, with the exception of forms that appear to be specifically 

 identical with Pectunculus veatchi and Tellina lioffmaniana, are absent. One of 

 the forms which I have referred to Heteroterma was probably identified by 

 Gabb as Perissolax brevirostris, and his Gyrodes expansa was probably also an 

 erroneous identification. 



The palaeontologieal evidence, therefore warrants the reference of the 

 "intermediate beds" to the lower part of the Tejon as it is developed in the 

 Mount Diablo region, where some localities of the same zone must have been 

 included in Gabb 's Martinez Group. 



Owing to the absence of other recognizable horizons, the stratigraphy of 

 the Lower Lake region adds little to our knowledge of the position of the zone. 

 The fossils enumerated above occur not more than 300 to 400 feet north of 

 the southern edge of a belt about two miles wide, consisting largely of light- 

 colored sandstones with some beds of clay and bands of conglomerate. The 

 strike is nearly east and west, and the dip is very high, often vertical. South 

 of this sandstone there are heavy beds of crumpled clay shales with thin 

 sandstones and occasional calcareous lenses. These are doubtless of Cretaceous 

 age, but in the absence of fossils their exact horizon could not be determined. 

 Precisely similar beds occur on the north side of the sandstone belt at a 

 locality on the north side of Cache Creek about two and a half miles northwest 

 of Lower Lake, and some 400 feet within the sandstone belt a number of the 

 Lower Tejon species were found, including 



This locality is about two miles across the strike from the localities that 

 yielded the larger collection from the same horizon. It is evident that we 

 have here a closely folded syncline, the rocks between the two localities of 

 Lower Tejon probably having a thickness of 3000 or 4000 feet. The few fossils 

 that have been found in the intervening beds include an Ostrea, a Natica, and 

 Crassatella uvasana Conrad, the latter being an upper Tejon species. Possibly 

 there are later beds in the middle of the fold, but it is more probable that the 

 entire thickness belongs to the Tejon. 



Dr. Weaver later visited the Lower Lake section and made a collec- 

 tion of fossils from the locality on Herndon Creek. In August, 1912, 

 Packard and Dickerson, while collecting fossils for the Department of 

 Palaeontology of the University of California, made a stratigraphic 

 study of the Eocene series and the beds in contact with them. The 

 accompanying map (fig. 4) was made at that time. The Eocene in 

 this region is folded in a plunging asymmetric syncline with an east- 

 west axis which is located nearer to the steeply dipping south limb 



Ostrea appressa Gabb 

 Pern a, sp. 



Leda alaeformis (Gabb) 

 Meretrix, sp. 



Tellina, sp. 



Dentalium cooperi Gabb 

 Turritella pachecoensis Stanton 

 Natica, sp. 

 Ancillaria, sp. 



STRATIGRAPHY AND STRUCTURE 



