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 455 m thick is dominated by volcanic diamictites interpreted as lahars, with minor lithic lapilli-tuff and epiclastic volcanic sandstone.
Identifer | oai:union.ndltd.org:pdx.edu/oai:pdxscholar.library.pdx.edu:open_access_etds-4763 |
Date | 01 January 1987 |
Creators | Stine, Cynthia Marie |
Publisher | PDXScholar |
Source Sets | Portland State University |
Detected Language | English |
Type | text |
Format | application/pdf |
Source | Dissertations and Theses |
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