Advisor

Paul E. Hammond

Date of Award

1987

Document Type

Thesis

Degree Name

Master of Science (M.S.) in Geology

Department

Geology

Physical Description

1 online resource (94 p.)

Subjects

Stratigraphic geology -- Oligocene, Geology -- Washington (State) -- Ohanapecosh Formation, Volcanism -- Washington (State) -- Ohanapecosh Formation, Sedimentation and deposition -- Washington (State) -- Ohanapecosh Formation

DOI

10.15760/etd.5638

Abstract

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.

Description

If you are the rightful copyright holder of this dissertation or thesis and wish to have it removed from the Open Access Collection, please submit a request to pdxscholar@pdx.edu and include clear identification of the work, preferably with URL

Persistent Identifier

http://archives.pdx.edu/ds/psu/21174

plate_1a.pdf (3126 kB)
Plate 1a

plate_1b.pdf (890 kB)
Plate 1b

plate2.pdf (3024 kB)
Plate 2

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