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Stratigraphy Of The Ohanapecosh Formation North Of Hamilton Buttes, Southcentral Washington, Cynthia Marie Stine
Stratigraphy Of The Ohanapecosh Formation North Of Hamilton Buttes, Southcentral Washington, Cynthia Marie Stine
Dissertations and Theses
Over 1055 m of early Oligocene andesitic-dacitic volcaniclastic rocks and minor interbedded andesitic lava flows of the Ohanapecosh Formation are exposed in a dissected structural high in the southern Washington Cascade Range, about 22 km southwest of Packwood, Washington.
The exposed sequence of rocks in the study area are located approximately 250 m above the base of the Ohanapecosh Formation. A lower sequence of deposits, about 350 m in thickness, are dominated by primary and reworked lithic lapilli-tuff and epiclastic channelized volcanic sandstone and conglomerate. These sediments are interpreted as pyroclastic flows and stream deposits, respectively. The upper sequence, about …