PROCEEDINGS 



OF THE 



AMERICAN PHILOSOPHICAL SOCIETY 



HELD AT PHILADELPHIA 

 FOR PROMOTING USEFUL KNOWLEDGE 



Vol. LII 



November-December, 1913 



No. 212 



THE MARINE TERTIARY STRATIGRAPHY OF THE 

 NORTH PACIFIC COAST OF AMERICA. 



By RALPH ARNOLD and HAROLD HANNIBAL. 



(Plates XXXVH-XLVHL) 

 Columnar Section of the Columbia River and Shoalwater Bay District. 



Pleistocene marine terraces, 50' 



Pliocene basalt 



Monterey formation, 400' 



Seattle formation 

 tuffaceous shales and sand- 

 stone with interbedded basalts 

 of Nazel, Grays River, Ilwaco, 

 and Astoria. 



5.000' 



San Lorenzo formation 

 tuffaceous sandstones and 

 shales with interbedded basalts 

 of Winlock, Pe Ell, Holcomb, 

 Clatskanie, and Scapoose. 

 10,000' 



PROC. AMER. PHIL. SOC, LII. 212 R, PRINTED NOV. 7, I9I3. 



559 



