Carboniferous-Permian sedimentary and volcanic rocks

Predominantly sedimentary rocks. Graywacke, argillite, and slate; includes minor marble, siltstone, arkose, conglomerate, ribbon cherts, and volcanic rocks. Some Devonian rocks may be included in northwestern Washington.
State Washington
Name Carboniferous-Permian sedimentary and volcanic rocks
Geologic age Devonian to Permian, minor Mesozoic
Lithologic constituents
Sedimentary > Clastic > Sandstone > Graywacke (Bed)
Sedimentary > Chemical > Chert (Bed)
Sedimentary > Clastic > Mudstone > Shale (Bed)
Metamorphic > Metasedimentary > Metaclastic > Argillite
Sedimentary > Clastic > Sandstone > Arkose (Bed)
Metamorphic > Metasedimentary > Metaclastic > Quartzite
Sedimentary > Clastic > Siltstone (Bed, Tuffaceous)Includes some tuffaceous siltstone.
Metamorphic > Metasedimentary > Metaclastic > Phyllite
Igneous > Volcanic > Mafic-volcanic (Flow, Flow-pillows)Basaltic and andesitic and includes some pillow basalt (Misch, 1966).
Metamorphic > Metasedimentary > Metacarbonate > Marble
Metamorphic > Metasedimentary > Metaclastic > Slate
Sedimentary > Carbonate > Limestone (Bed)
Sedimentary > Clastic > Conglomerate (Bed)
Comments Dragovich and others, 2002, reports that this unit is mostly metamorphosed sedimentary rocks of the types listed above. Both the Cultus Formation and the Nooksack Formation have "flysch-like aspects", representing marine accumulation, likely in deep water (Misch, 1966).
Stratigraphic units Chilliwack Formation (in part); Cultus Formation (in part); Nooksack Group

Huntting, M.T., Bennett, W.A.G., Livingston, V.E.Jr., and Moen, W.S., 1961, Geologic Map of Washington: Washington Division of Mines and Geology, scale 1:500,000.

Misch, P., 1977, Bedrock Geology of the North Cascades, in Brown, E. H. and Ellis, R. C. (eds.), Geological Excursions in the Pacific Northwest, Geological Society of America 1977 Annual Meeting, Seattle: Western Washington University, p. 1-62.

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.

Tabor, R.W., Haugerud, R.A., Booth, D.B., Brown, E.H., 1994, Preliminary Geologic Map of the Mount Baker 30- by 60-Minute Quadrangle, Washington: U. S. Geological Survey Open File Report 94-403, 55p., 2 pls.

Misch, P., 1966, Tectonic evolution of the northern Cascades of Washington--A west-cordilleran case history. In Canadian Institute of Mining and Metallurgy; and others, A symposium on the tectonic history and mineral deposits of the western Cordillera in British Columbia and neighboring parts of the United States, Vancouver, 1964: Canadian Institute of Mining and Metallurgy Special Volume 8, p. 101-148, 1 pl.

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Counties Skagit - Snohomish - Whatcom