JPROCEEDINGS 



OF THE 



CALIFORNIA ACADEMY OF SCIENCES 



Fourth Series 

 Vol. VI, No. 2, pp. 19-40. May 6, 1916 



II 



THE POST-EOCENE FORMATIONS OF WESTERN 

 WASHINGTON 



BY 



Charles E. Weaver 

 Assistant Professor of Geology, University of IVashington, Seattle 



INTRODUCTION 



Marine deposits of post-Tejon age form a considerable 

 part of the formations exposed at the surface in western Wash- 

 ington. They have been folded and eroded, and, in some areas, 

 are deeply buried beneath sand and gravel of glacial and flu- 

 viatile origin. As a result, outcrops are usually found in the 

 form of low cliffs along the banks of rivers and creeks or along 

 the sea cliffs of the Sound or ocean. Certain portions of these 

 Oligocene-Miocene formations yield fairly abundant marine 

 invertebrate faunas. Upon a faunal basis five separate divi- 

 sions of the post-Tejon portion of the Tertiary can be recog- 

 nized. Marine deposits of Pliocene age with the exception of 

 a very small area on the western side of the Olympic Peninsula 

 are unknown within the state. Hie uppermost division or 

 upper Miocene is separated from the lower four divisions by 

 a well-marked unconformity. The pre-Pleistocene formations 

 of the southwestern portion of the state are somewhat ob- 



May 6, 1916 



