448 J HARLEN BRETZ 



the Willapa Bay region by distributaries of the Columbia during 

 the Satsop aggradation. 



The Satsop formation in the Willapa Bay region is a little more 

 than 75 feet in maximum exposed thickness, with the base below 

 tide. The strata are horizontal or depart from that attitude only 

 in gentle undulations. 



The formation may be traced back up the Willapa valley into 

 terraces of a decayed and red-stained river gravel which rests on 

 eroded Eocene basalt and Miocene sandstone. The relation 

 between the coastal and valley phases in the Willapa valley is the 

 same as that in the Chehalis valley. 



The Satsop formation along the coast of Oregon. — -J. S. Diller 1 

 has described Quaternary sediments along the Oregon coast which 

 belong clearly to the same formation as those along the coast of 

 Washington. Diller did not name this formation and it has sub- 

 sequently received but passing mention in the literature. Hence 

 the name "Satsop" is here extended to cover that Quaternary 

 formation of the Pacific Coast whose minimum limits reach from the 

 Strait of Juan de Fuca north of Washington to the Coquille valley, 

 within 80 miles of the Oregon-California line. 



Exposures of the Satsop formation examined by Diller are as 

 follows : 



Ilwaco, Washington: 14 feet of gravel, sand, and clay, the 

 top lying 30 feet above tide. Contains fresh shells of living 

 species of mollusks. Unconformable on tilted shales of Oligo- 

 cene age. 



Tillamook Bay, Oregon: 20 feet of sandstone, capping a 

 bluff of basalt 300 feet high. 



Yaquina Bay, Oregon: Nye Beach: 40 feet of horizontally 

 bedded gray sand overlying 20 feet of tilted Miocene shales. 

 Sand contains logs, branches, and roots, some roots apparently 

 in situ. Another section: 10 feet of yellow sand overlain by 5 feet 

 of indurated gravel, this overlain by 6 feet of sand. Another 

 section: 30 feet of Quaternary materials containing cones identified 

 by F. Ff. Knowlton as of tideland spruce. 



1 J. S. Diller, "A Geological Reconnaissance in Northwestern Oregon," U.S. Geol. 

 Surv., 17th Ann. Rept., Part I, 1896. 



