200 University of California Publications in Geology [Vol. 7 



San Pedro, Arnold, 1903.— In 1903, Ralph Arnold, 38 in "The 

 Palaeontology and Stratigraphy of the Marine Pliocene and 

 Pleistocene of San Pedro, California," stated that "The oldest 

 formation exposed in the immediate vicinity of San Pedro is 

 the Miocene, or Monterey series. The shales of this formation 

 are exposed along the sea cliff in the eastern end of San Pedro 

 Hill and also on Deadman Island" (p. 12). 



Petroleum Districts, Eldridge, 1903. — In Contributions to 

 Economic Geology for 1902, 30 Eldridge gave an outline of the 

 geology of the various oil districts of California. He described 

 formations referable to the Monterey series in the following 

 localities: Coalinga ("100 or 200 feet of clays and sandstones 

 that may prove to be Lower Miocene ; 200 feet of siliceous shales 

 typical of the Monterey (Upper Miocene) ") ; McKittrick ("prin- 

 cipally of siliceous shales with their chalky, earthy, or more 

 argillaceous modifications") ; Sunset ("local developments of 

 gritty sands, brown and yellow limestones, and gypsiferous clays, 

 perhaps a lower division of the Miocene, the upper division con- 

 sisting of siliceous shales, typical of the Monterey") ; Kern River 

 Field (called Lower Miocene) ; La Graeiosa District (Monterey 

 shale) ; Summerland Field (siliceous shales of the Monterey) ; 

 Santa Clara Valley (Lower Miocene, and Monterey shales) ; 

 Los Angeles Field (siliceous shales of Monterey type) ; Puente 

 Hills ("Lower Miocene, and Monterey"). 



It is to be noted that while Eldridge definitely refers certain 

 formations in these fields to the Monterey (or to the Monterey 

 shale), yet he suggests that certain underlying sands or shales 

 may be Lower Miocene and therefore older than the Monterey. 

 This foreshadows the erection of a separate formation group and 

 name for these lower beds that is definitely put forward by 

 others the following year. 



General Character of Decade 1893-1903. — We see, then, that 

 from 1893 to 1903 the unity of the series was accepted by the 

 various workers in California Tertiary geology, the name Mon- 

 terey for the whole series was the only local designation used, 

 and its areal distribution was recognized along the coast from 

 Point Arena to San Clemente Island. 



as Calif. Acad. Sci. Memoirs, vol. 3 (1903). 

 3f>U. S. Geo!. Surv. Bull. 213, pp. 306-321, 1903. 



