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Upper Tertiary volcanic rocks, undivided

Mostly massive andesite flows, flow breccia, and pyroclastic material; includes some basalt flows and sedimentary rocks.
StateWashington
NameUpper Tertiary volcanic rocks, undivided
Geologic ageMiocene-Oligocene
Original map labeluTv
CommentsSmith, 1993, indicates that much of this is Oligocene dacite.
Primary rock typedacite
Secondary rock typeandesite
Other rock typesrhyolite; sandstone; siltstone; conglomerate
Lithologic constituents
Major
Igneous > Volcanic > Felsic-volcanic > Dacite (Volcaniclastic, volcanic breccia)
Igneous > Volcanic > Mafic-volcanic > Andesite (Volcaniclastic, volcanic breccia)
Minor
Igneous > Volcanic > Felsic-volcanic > Dacite (Flow)
Igneous > Volcanic > Mafic-volcanic > Andesite (Flow)
Incidental
Sedimentary > Clastic > Conglomerate (Bed)
Sedimentary > Clastic > Sandstone (Bed)
Igneous > Volcanic > Felsic-volcanic > Rhyolite (Pyroclastic, tuff)
Igneous > Volcanic > Felsic-volcanic > Dacite (Pyroclastic, tuff)
Igneous > Volcanic > Mafic-volcanic > Andesite (Pyroclastic, tuff)
Igneous > Volcanic > Felsic-volcanic > Rhyolite (Flow)
Igneous > Volcanic > Felsic-volcanic > Rhyolite (Volcaniclastic, volcanic breccia)
Sedimentary > Clastic > Siltstone (Bed)
Map references
Huntting, M. T., Bennett, W. A. G., Livingston, V. E. Jr., Moen, W. S., 1961, Geologic Map of Washington: Washington Division of Mines and Geology, scale 1:500,000.
Unit references
Huntting, M. T., Bennett, W. A. G., Livingston, V. E. Jr., Moen, W. S., 1961, Geologic Map of Washington: Washington Division of Mines and Geology, scale 1:500,000.
Smith, J. G., 1993, Geologic Map of Upper Eocene to Holocene Volcanic and Related Rocks in the Cascade Range, Washington; U. S. Geological Survey Miscellaneous Investigations Series Map I-2005, scale 1:500,000.
Dragovich, J. D., Logan, R. L., Schasse, H. W., Walsh, T. J., Lingley, W. S., Jr., Norman, D. K., Gerstel, W. J., Lapen, T. J., Schuster, J. E., Meyers, K. D., 2002, Geologic Map of Washington-Northwest Quadrant: Washington Division of Geology and Earth Resources Geologic Map GM-50, scale 1:250,000.
Geographic coverageSnohomish

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