46 CALIFORNIA ACADEMY OF SCIENCES [Proc. 4th Ser. 



surface are deposits of glacial drift. Presumably they are in- 

 volved in a broad synclinal basin beneath the glacial drift of 

 northern Kitsap County. The evidence for such a sugges- 

 tion is to be found to the northwest on the Ouiniper Peninsula 

 between Quilcene and Port Townsend. In that region the 

 same Oligocene strata resting unconformably upon the Eocene 

 basalts exist in a broad synclinal fold whose axis trends south- 

 easterly and passes beneath the glacial covering of northern 

 Kitsap County. It can be seen from the foregoing statements 

 that the Oligocene beds exposed at the entrance to the Bremer- 

 ton Navy Yard are a representative part of the Oligocene 

 formations of the Puget Sound basin and as such are worthy 

 of detailed study. 



In the investigation of this particular region transit sur- 

 veys were made along the shore lines wherever pre-glacial 

 formations were exposed. All observations taken on the strike 

 and dip of the strata were tied in to these traverses. Strati- 

 graphic sections were also made with the aid of the transit. 

 The distribution of the Oligocene strata as exposed along the 

 shore lines, as w^ell as the structural data, may be seen by re- 

 ferring to Fig. 1. 



The Oligocene strata of this region are entirely of sedi- 

 mentary origin. The Eocene lavas upon which these sedi- 

 ments rest are exposed about two miles southwest of Bremer- 

 ton on the west shore of Sinclair Inlet. The position on the 

 surface of the contact between the Eocene andesites and the 

 Oligocene sediments in this region is concealed beneath de- 

 posits of glacial drift. Many of the pebbles forming the basal 

 conglomeratic phases of the Oligocene strata are composed 

 in part of the older andesite. 



The loweiTnost strata exposed in this area outcrop at Or- 

 chard Point. The highest occur along the north shore of 

 the entrance to Blakeley Harbor. The total thickness of the 

 deposits as exposed between the lower and uppermost beds is 

 approximately 8900 feet. The following generalized strati- 

 graphic column is constructed from observations taken along 

 the section (B-B') : 



