Pre-Middle Jurassic sedimentary and volcanic rocks

Sedimentary and volcanic rocks, undivided. Graywacke, argillite, slate, greenstone, and spilitic volcanic rocks.
State Washington
Name Pre-Middle Jurassic sedimentary and volcanic rocks
Geologic age Late Paleozoic deposition? with Cretaceous metamorphism?
Lithologic constituents
Sedimentary > Chemical > Chert (Bed)
Metamorphic > Metaigneous > Metavolcanic (Greenschist)Includes spilite, greenstone, meta-andesite and meta-basalt.
Metamorphic > Metasedimentary > Metaclastic > ArgilliteCalcareous; grades into phyllitic slate in north King County; black in Skagit County.
Sedimentary > Clastic > Sandstone > Graywacke (Bed)
Metamorphic > MetasedimentaryIncludes metagraywacke, "metagrit", meta-conglomerate, and slate.
Sedimentary > Clastic > Conglomerate (Bed)
Metamorphic > Metasedimentary > Metaclastic > QuartziteMeta-chert.
Comments Original sedimentary and volcanic rocks are largely deformed and metamorphosed Tertiary plutonism destroyed greenschist facies minerals and now many rocks are pyroxene hornfels (Tabor and others, 1993).

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.

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.

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., Booth, D.B., Vance, J.A., Ford, A.B., Ort, M.H., 1988, Preliminary geologic map of the Sauk River 30 by 60 minute quadrangle, Washington: U. S. Geological Survey Open File Report 88-692, 51 p., 1 pl.

NGMDB product
Counties King - Skagit - Snohomish