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Oligocene marine rocks

Massive, tuffaceous and nontuffaceous sandstone and siltstone; locally concretionary; includes conglomerate along the north coast of Olympic Peninsula and basaltic sandstone east of Chehalis.
State Washington
Name Oligocene marine rocks
Geologic age Late Eocene to Late Oligocene
Primary rock type siltstone
Secondary rock type sandstone
Other rock types conglomerate; tuff; mudstone
Lithologic constituents
Major
Sedimentary > Clastic > Sandstone (Tuffaceous)
Sedimentary > Clastic > Siltstone (Tuffaceous)
Minor
Sedimentary > Clastic > Sandstone (Bed)Includes basaltic and glauconitic sandstone of Lincoln Formation (Wagner, 1967a, b, Snavely and others, 1958) as well as arenite and graywacke of Hoko Formation (Babcock and others, 1994).
Incidental
Sedimentary > Clastic > Conglomerate (Lense)
Igneous > Volcanic (Pyroclastic, tuff)
Sedimentary > Clastic > Mudstone (Bed)
Sedimentary > Clastic > Siltstone (Bed)
Sedimentary > Clastic > Conglomerate (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.
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.
Wagner, H. C., 1967a, Preliminary geologic map of the South Bend quadrangle, Pacific County, Washington: U. S. Geological Survey Open File Reports 67-266, scale 1:62,500.
Wagner, H. C., 1967b, Preliminary geologic map of the Haymond quadrangle, Pacific County, Washington, U. S. Geological Survey Open File Reports 67-265, scale 1:62,500.
Snavely, P. D., Jr., Brown, R. D., Roberts, A. E., Rau, W. W., 1958, Geology and Coal Resources of the Centralia-Chelalis District, Washington: U. S. Geological Survey Bulletin 1053, 149 p.
Walsh, T. J., 1987, Geologic Map of the Astoria and Ilwaco Quadrangles, Washington and Oregon: Washington Division of Geology and Earth Resources Open File Report 87-2, scale 1:100,000.
Counties Clallam - Grays Harbor - Jefferson - King - Lewis - Mason - Pacific - Skagit - Snohomish - Thurston - Wahkiakum