Tertiary volcanic rocks, undivided (WATv;0)

State	Washington
Name	Tertiary volcanic rocks, undivided
Geologic age	Mostly Oligocene-Eocene
Original map label	Tv
Comments	Stoffel and others, 1991, report that while the term "Pend Oreille andesite" was once widely used, it has since been abandoned. This unit appears to be primarily andesite, followed closely and possibly matched by dacite; rhyolite occurs only incidentally; no mention of basalt in referenced literature.
Primary rock type	andesite
Secondary rock type	dacite
Other rock types	rhyolite
Lithologic constituents	Major Igneous > Volcanic > Felsic-volcanic > Dacite (Flow) Igneous > Volcanic > Mafic-volcanic > Andesite (Flow) Minor Igneous > Volcanic > Mafic-volcanic > Andesite (Volcaniclastic, volcanic breccia) Igneous > Volcanic > Felsic-volcanic > Dacite (Volcaniclastic, volcanic breccia) Incidental Igneous > Volcanic > Felsic-volcanic > Rhyolite (Pyroclastic, ash-flow) Igneous > Volcanic > Mafic-volcanic > Andesite (Pyroclastic) Igneous > Volcanic > Felsic-volcanic > Dacite (Pyroclastic, tuff) Igneous > Volcanic > Mafic-volcanic > Andesite (Dike or sill)
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. Stoffel, K. L., Joseph, N. L., Waggoner, S. Z., Gulick, C. W., Korosec, M. A., Bunning, B. B., 1991, Geologic Map of Washington--Northeast Quadrant: Washington Division of Geology and Earth Resources Geologic Map, GM-39, scale 1:250,000. Schroeder, M. C., 1952, Geology of the Bead Lake District, Pend Oreille County, Washington: Washington Division of Mines and Geology Bulletin No. 40, 57 p. Rinehart, C. D., and Fox, K. F., Jr., 1976, Bedrock Geology of the Conconully Quadrangle, Okanogan County, Washington: U. S. Geological Survey Bulletin 1402, 58 p. [http://pubs.er.usgs.gov/publication/b1402] Rinehart, C. D., and Fox, K. F., Jr., 1972, Geology and Mineral Deposits of the Loomis Quadrangle, Okanogan County, Washington: Washington Division of Mines and Geology Bulletin No. 64, 124 p. Tabor, R. W., Frizzell, V. A., Jr., Booth, D. B., Waitt, R. B., Whetten, J. T., Zartman, R. E., 1993, Geologic Map of the Skykomish River 30- by 60-Minute Quadrangle, Washington: U. S. Geological Survey Miscellaneous Investigations Series Map I-1963, scale 1:100,000. [http://pubs.er.usgs.gov/publication/i1963] Joseph, N. L., 1990b, Geologic Map of the Nespelem 1:100,000 Quadrangle, Washington: Washington Division of Geology and Earth Resources Open File Report 90-16, 47 p., 1 pl.
Geographic coverage	Chelan - Ferry - King - Kittitas - Okanogan - Pend Oreille - Snohomish - Stevens - Whatcom