I9I3.] STRATIGRAPHY OF PACIFIC COAST OF AMERICA. 563 



General Remarks. 



The recognition of marine tertiary on the North Pacific Coast 

 of America dates back to 1848 when ConracF described several 

 fossil mollusca from " the tertiary deposits on the Columbia River 

 near Astoria." More recent studies by Richardson, Condon, Diller, 

 Willis and Smith, the senior author, and other writers too numerous 

 to mention have shown that such rocks underlie all of Oregon west 

 of the Cascade Range and north of the Klamath-Siskiyou Mountains^ 

 western Washington except the Olympic Range, and portions of 

 Vancouver Island. The several geological horizons have in most 

 instances been named and something is known of their fossil con- 

 tents but their stratigraphic relations one to another and their correl- 

 atives among the closely related formations of California are scarcely 

 understood. 



Several years ago the senior writer visited the more important 

 fossil localities then known in western Oregon and Washington in 

 the interests of the United States Geological Survey. No general 

 report of the work was published owing to the necessity of further 

 field studies but descriptions of the stratigraphy of particular dis- 

 tricts are to be found in " Gold Placers of the northwestern coast 

 of Washington,"- " Coal in Clallam County, Washington "^ and " A 

 Geological Reconnaissance of the Olympic Peninsula."* Some of 

 the palasontological material obtained was described in " The Terti- 

 ary and Quaternary Pectens of California,"^ " Descriptions of New 

 Cretaceous and Tertiary Fossils from the Santa Cruz Mountains,. 

 California "*' and " The Miocene of Astoria and Coos Bay, Oregon."^ 

 The distribution of land and water in this region during the different 

 tertiary periods is treated of in a preliminary way in " Environ- 

 ment of the Tertiary Faunas of the Pacific Coast of the United 

 States."^ 



^ Amer. Jl. Sci., 2d series, V., 1848, p. 432. 



2 Arnold, R., Bull. 260, U. S. Geol. Sur., 1905, p. 154-7, Fig. 11. 



3 Ibid., p. 413-421. 



4 Arnold, R., Bull. Geol. Soc. Am., XVII., 1906, p. 451-468, PI. 55-58. 



5 Arnold, R., Prof. Pap. 47, U. S. Geol. Sur., 1906, 264 pp., 53 PI. 



« Arnold, R., Proc. U. S. Nat. Mus., XXXIV., 1908, p. 345-390, PL 

 XXXI.-XXXVII. 



^ Dall, VV. H., Prof. Pap. 59, U. S. Geol. Sur., 1909, 284 pp., 23 PI. 

 ^ Arnold, R., Jour, of Geol., XVII., 1909, p. 509-533. 



