32 TERTIARY AND QUATERNARY PECTENS OF CALIFORNIA. 



probably' the best development of the fossiliferous marine Pleistocene on the 



coast is exposed. This locality is taken, therefore, as the type for the Pleistocene 



of California. 



SAN PEDRO FORMATWX. 



TYPE LOCALITY. 



The type locality is yicinity of San Pedro. Los Angeles County, Cal. 



NAME AND DESCRIPTION. 



This formation was named and described h\ W. H. Dall, Table of North Ameri- 

 can Tertiary horizons: Eiohtcenth Ann. Kept. U. S. Geol. Survey, pt. 2, 1898, p. 335. 



DEFINITION. 



As redefined by the writer,'^' this formation includes '" all of the strata of 

 Deadman Island and San Pedro lying- stratigraphically above the brown Pliocene 

 sandstone and l)elow the raised beach formation of Deadman Island."" In the 

 type locality the San Pedro consists of a series of conglomerates and sands, 

 both more or less incoherent and extremely fossiliferous, with a total thickness 

 of approximately 100 feet. Near Ventura, l)eds of probable similar age attain a 

 thickness of about 1,000 feet. 



The formation may be divided into two distincthorizons — a lower and an upper — 

 separated at all points in the vicinity of the type locality by an unconformity. The 

 lower part of the formation represents at least the base of the Pleistocene, and may 

 jiossibly extend into the Pliocene. It is probably contemporaneous with the upjser 

 portion of the Merced, and contains a fauna which appears to be transitional between 

 that of the Pliocene on which it rests and that of the characteristic Pleistocene above. 



The upper Ix'ds of the San Pedro formation are cei'tainly Pleistocene, and as their 

 fauna is more or less characteristic it will be cited as typical of the major portion of 

 the Pleistocene. 



LOCALITIES. 



Deposits contemporaneous in a general way with the San Pedro formation, jiar- 

 ticularlv the upper division, occur at numerous places along the coast from Alaska 

 to Lower California. Only those localities known to be fossiliferous will be cited, 

 however. They are as follows: 



Point Holmes, Comox, Vancouver Island, British Columbia (Newcombe). 

 Port Blakelev, near Seattle, Wash., and other localities in the Puget Sound country. 

 Fossil Point, Coos Bay, Oreg. (Dall, 1808, p. ;?36). 



Ilwaco. near the mouth of the Columliia River, and Newport, Oreg. (Diller, IS'Jti, p. 479 ct seq.) 

 Fort Ross, Humboldt County. 



Purisima and Punta Ano Nuevo, San Mateo County. 



South shore of San Pablo Bay (unconformably above the San Pablo formation), Contra Costa County. 

 Santa Cruz, Santa Cruz County. 



Vicinity of Ventura and Summerland, Ventura County. 



San Pedro, Long Beach, Bells Station, and Los Cerritos Hill, Los Angeles County. 

 Newport, Orange County. 

 Two miles south of Delmar, Pacific Beach, Spanish Bight, and San Diego, San Diego County. 



a Arnold, Delos and Ralph, The marine Pliocene and Pleistocene stratigraphy of the coast of southern California: 

 Jour. Geol., vol. 10, 1902, p. 124. 



