1913-] STRATIGRAPHY OF PACIFIC COAST OF AMERICA. 587 



logical standpoint, is total absence on the North Pacific Coast of 

 any beds in this formation, or in any other formation for that 

 matter, lithologically similar to the diatomaceous shales so preva- 

 lent in ^Monterey of California. This became vital, however, from 

 the point of view of the economic geologist since upon the 

 presence of such shales or similar organic deposits equally lacking 

 here, depends the possibilities of the discovery of petroleum in 

 commercial quantities. Except for coal near Clallam Bay, Wash- 

 ington,*- and on the North Nehalem River in Oregon*' no organic 

 products of economic value are known in this formation. 



The Monterey formation of this region ordinarily consists of 

 two members; the lower a massive buff sandstone often containing 

 thin lignite seams and attaining south of the Chehalis River a thick- 

 ness of perhaps 1,500 feet; the upper fine soft clay shales perhaps 

 2,500 feet thick in the same section which is one of the most complete. 



To this formation are referred the conglomerates overlying the 

 San Lorenzo shales at Carmanah Point on Vancouver Island; and 

 in Washington: the Clallam section and the conglomerates uncon- 

 formable on the Seattle beds between West Clallam and the Hoko 

 River; a small area of Tertiary sandstone faulted into the so-called 

 Cretaceous north of the Hoh River; an area of shales faulted against 

 the Empire formation on the upper Wishkah River; the westward 

 dipping monoclinal section from a few miles west of Elma to North 

 River Junction on the south side of the Chehalis River and equiva- 

 lent strata south to the Willipa River ; and an isolated area beneath 

 the Pliocene basalt on Elocheman River about twelve miles above 

 the Columbia. In Oregon isolated areas lying on the Astoria series 

 or exposed beneath the Pliocene basalt at Alountain Dale, Westport, 

 the foot of 19th Street at Astoria, and the south shore of Tillamook 

 Harbor are of this age as well as a narrow belt of rocks faulted 

 against the Astoria series and extending for several miles up and 

 down the coast west of Newport. 



The following species were obtained in the Clallam section and 

 at Astoria. 



42 R. Arnold, Bull. 260, U. S. Geol. Sur., 1905, p. 413-4-27- 



43 J. S. Diller, 17th Ann. Rept. U. S. Geol. Sun, Pt. I., 1896, p. 494- 



