Skip to main content

Pre-upper Eocene rocks

Argillite and graywacke between inner and outer volcanic belts in Olympic Peninsula. Sheared carbonaceous argillite, argillite, graywacke, and minor conglomerate lenses and altered lava flows in western Yakima County.
State Washington
Name Pre-upper Eocene rocks
Geologic age Eocene (Olympic Peninsula); Cretaceous(?) (Yakima County)
Primary rock type sandstone
Secondary rock type argillite
Other rock types siltstone; conglomerate; mudstone; limestone; chert; greenstone; basalt
Lithologic constituents
Major
Sedimentary > Clastic > Sandstone (Bed)Lithofeldspathic in Yakima County; volcaniclastic (basaltic) to micaceous in Olympic Peninsula.
Minor
Metamorphic > Argillite
Incidental
Sedimentary > Clastic > Conglomerate (Bed)
Sedimentary > Clastic > Mudstone (Bed)
Sedimentary > Carbonate > Limestone (Bed)
Sedimentary > Chemical > Chert (Bed)
Metamorphic > Greenstone
Igneous > Volcanic > Mafic-volcanic > Basalt (Flow)
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.
Walsh, T. J., Korosec, M. A., Phillips, W. M., Logan, R. T., Schasse, H. W., 1987, Geologic Map of Washington-Southwest Quadrant: Washington Division of Geology and Earth Resources, Geologic Map GM-34, scale 1:250,000.
Babcock, R. S., Suczek, C. A., Engebretson, D. C., 1994, The Cresent "Terrane", Olympic Peninsula and Southern Vancouver Island, in Lasmanis, R. and Cheney, E. S., convenors, Regional Geology of Washington State: Washington Division of Geology and Earth Resources Bulletin 80, p. 141-157.
Snavely, P. D., MacLeod, N. S., Niem, A. R., 1993, Geologic map of the Cape Flattery, Challam Bay, Ozette Lake, and Lake Pleasant Quadrangles, Northwestern Olympic Peninsula, Washington: U. S. Geological Survey Map I-1946, scale 1:48,000.
Tabor, R. W. and Cady, W. M., 1978, Geologic Map of the Olympic Peninsula, Washington: U. S. Geological Survey Miscellaneous Investigations Series Map I-994, scale 1:125,000.
Counties Clallam - Grays Harbor - Mason - Yakima