Portland State University PDXScholar Dissertations and Theses Dissertations and Theses 1981 A geochemical study of the Rhododendron and Dalles formations in the area of Mount Hood, Oregon Marshall W. Gannett Portland State University Follow this and additional works at: https://pdxscholar.library.pdx.edu/open_access_etds Part of the Geochemistry Commons, and the Plant Sciences Commons Let us know how access to this document benefits ou.y Recommended Citation Gannett, Marshall W., "A geochemical study of the Rhododendron and Dalles formations in the area of Mount Hood, Oregon" (1981). Dissertations and Theses. Paper 3166. https://doi.org/10.15760/etd.3162 This Thesis is brought to you for free and open access. It has been accepted for inclusion in Dissertations and Theses by an authorized administrator of PDXScholar. Please contact us if we can make this document more accessible:
[email protected]. AN ABSTRACT OF THE THESIS OF Marshall W. Gannett for the Master of Science in Geology presented January 21, 1981. Title: A Geochemical Study of the Rhododendron and Dalles Formations in the Area of Mount Hood, Oregon. APPROVED BY MEMBERS OF THE THESIS COMMITTEE: vin H. Beeson, Chairman Richard E. Thoms Paul E. Hammond The Miocene Rhododendron and Dalles Formations in the Mount Hood area are accumula- tions of chiefly pyroclastic andesitic material, largely confined to the Dalles-Mount Hood syncline. These very similar units are geographically separated by overlying andesites including the present Mount Hood cone, and past workers (Hodge 1938, Wise 1969) have suspected that they may share a common source. Prior to this study, few geochemical data were available for the Rhododendron and the Dalles Formations, compared to the well studied Columbia River basalts underlying them and the overlying Pliocene a.ndesites.