20 TERTIARY AND QUATERNARY PECTENS OF CALIFORNIA. 



MOXTETiEY SHALE. 

 TYPE LOCALITY. 



The type locality is vicinity of Monterey, Monterey County, Cal. 



NAME AND DESCRIPTION. 



This formation was named and described by Williani 1*. Rlake in Proceedings 

 of the Academy of Natural Sciences of Philadelphia, vol. 7, 1855, pp. 328-331. 



DEFINITION. 



In describing the shale be Is in the vicinity of Monterey Blake has the fol- 

 lowing to say regarding the stratigraphic relations: "This interesting formation, 

 teeming with the skeletons of microscopic organisms, appears to overlie and to 

 be conformable with the Tertiary strata that underlie a part of the town of 

 Monterey and extend to and beyond the mission of San Carlos. These strata 

 rest upon a porphyritic granite, which forms the projection of the coast called 

 Point Pinos, and is the bulwark of the bay." The only fossils mentioned by 

 Blake as occurring in the formation are: Tellma congasta Conrad. Lutraria trasl'il 

 Conrad, and diatoms belonging to the genus Oocclnodlscus. 



The terra "Monterey shale," as now accepted, applies to the very characteristic 

 shale formation typically developed in the Santa Lucia and Santa Cruz ranges. 

 It sometimes attains a thickness of over 2,000 feet, and at some localities is 

 interbedded with layers of sandstone or thin strata of a rather impure limestone. 

 The formation is underlain conformably by the Vaqueros sandstone at most locali- 

 ties, but at a few it rests directly upon older rocks. In some places the line of 

 demarcation between the Vaqueros and Monterey is very distinct, while at others 

 the beds seem to merge into each other through a series of alternating sand and 

 shale layers. As suggested by Doctor Lawson, the shale probably has an inshore 

 e(juivalent of sandstone, whose fauna is doubtless entirely different from that of 

 the shale and probably shows a marked resemblance to that of the underlying 

 Vaqueros and overlying Contra Costa County Miocene. Following the deposition 

 of the Monterey came the great upheaval along the coast which resulted in the 

 elevation of the shales and their subsequent erosion. As a result of this a line 

 of marked unconformity generally separates the Monterey from the overlying 

 formations. 



LOCALITIES. 



Southeast of Pinole, Contra Cos^ta County. 



Langley Hill and Alpine district, San Mateo County. 



Castle Rock Ridge, Santa Clara County. 



Castle Rock Ridge, vicinity o£ Ben Lomond, Felton, Gibbs, and Santa Cruz, Santa Cruz County. 



IMonterey, Carmelo Valley, and Santa Lucia Range, Monterey County. 



Big Panoche Creek to Kreyenhagens, Fresno County. 



Templeton, Atascadero, Lopez Canyon, Point Buchon to near mouth of Davis Canyon, northeast of 



Arroyo Grande, and other localities in San Luis Obispo County. 

 Northwest of Tulare Lake, Tulare County. 



