ABSTRACTS OF PAPERS 131 



PLEISTOCENE OF WESTERN ^7ASHIN(JT0N 

 BY J. HARLEN BRETZ 



(Abstract) 



An early Pleistocene gravel deposit, the Satsop formation, is widely dis- 

 tributed along the Washington coast and In the Chehalis Valley. The Satsop 

 formation Is not found in the Puget Sound region, where glacial deposits cover 

 most of the country. 



Two glaciations are known in western Washington — the Admiralty and the 

 Vashon. A thick formation of stratified drift, the Admiralty sediments, was 

 deposited during the retreat of the Admiralty ice. During the succeeding 

 inter-Glacial epoch the Puyallup epoch, these deposits were eroded by streams 

 to form valleys now constituting Puget Sound. No truly interglacial deposits 

 are known in Puget Sound. The region appears to have been fully a thousand 

 feet higher during this inter-Glacial epoch than during the preceding Admiralty 

 or the following Vashon epochs. 



The Vashon glacier failed throughout most of the region to modify materi- 

 ally the topography produced during the Puyallup epoch. During its retreal 

 a series of glacial lakes formed in the valleys of inter-Glacial age. The region 

 at this time lay 50 or 75 feet lower than at present. 



Postglacial diastrophism embraces a complete oscillation of the Puget Sound 

 region, the sea having stood at least 290 feet above present tide at some time 

 subsequent to the Vashon epoch. 



Except for outwash of both Admiralty and Vashon age in certain valleys 

 of the Chehalis system, no events other than stream erosion are known to 

 record the later Pleistocene epochs in southwestern Washington. 



Presented without notes and illustrated by lantern slides. 

 The author replied to several questions raised by Lawson. 



The section adjourned for lunch at 11.55 to reconvene at 1.30. 



The afternoon session was called to order by the temporary chairman 

 at 1.55, and the minutes of the Fourteenth Annual Session were read 

 and approved. 



ELECTION OF OFFICERS 



After the report of the Nominating Committee, fho fol having were 

 elected as section officers for the year 1914-1915 : 



H. Poster Bain^ Chairman. 

 George D. Louderback, Secretary. 

 • Charles E. Weaver, Councilor. 



RUMMER MEETINC 



The secretary announced the decision of the Geological Society of 

 America to accept the invitation of the ( 'ordillcraii Section and hold a 

 X— Bull. Gkol. Soc. Am., Vol. -tl, r.»14 



