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University of California Publications in Geology [Vol.9 



to the south ; the Purisima Formation south of Halfmoon Bay, San 

 Mateo County; the later Neocene formations of the Sargent Oil 

 Field ; and the Wildcat Series in Humboldt County, California. 



Review op the Literature 



Aside from the incidental references to the geology of the 

 Pacific Coast made by the early scientists and explorers, such as 

 Captain Beechey and others, there are numerous publications which 

 have contributed much to our knowledge of the later Tertiary and 

 Quaternary formations of this region. The more important of these 

 papers will be briefly reviewed in their chronological order. 



Among the earliest publications is one by Dr. John B. Trask, in 

 which he discusses the geology of the Coast Range Mountains. In 

 this paper he defined the Santa Cruz Mountains and described the 

 geology of that region. 1 He applied the name "infusorial group" 

 to the shales now known as the Monterey shales. He described 

 slates and sandstones overlying the Monterey and found them fos- 

 siliferous. The latter are probably the beds that are now known 

 as the Purisima Formation. 



In 1856 Dr. W. P. Blake published an account of the geology of 

 the San Francisco Bay region. 2 The stratigraphy and lithology 

 of the beds exposed along the shores adjacent to the Golden Gate 

 and of the islands in the bay were fully discussed. The series of 

 sediments were considered to be of Tertiary age from fragments 

 of rocks washed upon the beach, near Point Lobos, containing fossil 

 echinoderms (Scutella interlineata) , which he supposed to be the 

 same rocks as those exposed at Point Lobos in place. The frag- 

 ments containing Scutella interlineata probably came from the Mer- 

 ced Series several miles farther south, which he apparently omitted 

 from the discussion. 



In 1865-66 the Geological Survey of California made a survey 

 of the coast region from San Francisco Bay south to San Diego. 3 

 The beds at Seven Mile Beach were called Pliocene, on the authority 

 of Gabb and Remond, and were said to be overlain by Post-Pliocene 

 sediments. The formations exposed along the coast south of Half- 



1 Senate Doc. no. 14, State of California, Session 1855. 



2 Pacific Railroad Reports, vol. 5, pp. 145, 1856. 



» Geol. Survey of Calif., J. D. Whitney, State Geologist, Geol. vol. 1, p. 61. 



