Triassic sedimentary rocks, undivided

Predominantly limestone, marble, and dolomite near Riverside in Okanogan County. Conglomerate, shale, graywacke, gritstone, and limestone on San Juan Island. Siltstone with greenstone locally on Orcas Island. Graywacke conglomerate, cherty greenstone, and limestone in northern Ferry County.
State Washington
Name Triassic sedimentary rocks, undivided
Geologic age Triassic with Permian where impossible to differentiate
Lithologic constituents
Sedimentary > Carbonate > Limestone (Bed, Lens)
Metamorphic > MetasedimentaryIncludes meta-argillite, metasandstone, metaconglomerate, metachert, and metamudstone, mostly on San Juan Islands (Dragovich and others, 2002).
Sedimentary > Carbonate > Dolostone (Bed)
Metamorphic > Metasedimentary > Metacarbonate > Marble
Sedimentary > Chemical > Chert (Bed)
Sedimentary > Clastic > Conglomerate (Bed)
Metamorphic > Metaigneous > Greenstone (Greenschist)Are tuffs, flows or intrusives depending on original rock (Parker and Calkins, 1964).
Sedimentary > Clastic > Siltstone (Bed)
Metamorphic > Metasedimentary > Metaclastic > Slate
Metamorphic > Metasedimentary > Metaclastic > Argillite
Sedimentary > Clastic > Sandstone (Bed)
Comments Limestone and dolomite in Asotin County (Martin Bridge Limestone). San Juan Islands consist mostly of metasedimentary rocks (see lithology coding).
Stratigraphic units Haro Formation; Martin Bridge Limestone; Constitution Formation (in part: Orcas Island); Orcas chert (in part)

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.

Parker, R.L. and Calkins, J.A., 1964, Geology of the Curlew Quadrangle Ferry County Washington, U.S. Geological Survey Bulletin 1169, 95 p.

Reidel, S.P., Hooper, P.R., Webster, G.D., Camp, V.E., 1992, Geologic Map of Southeastern Asotin County, Washington: Washington Division of Geology and Earth Resources Geologic Map GM-40, scale 1:48,000.

Brandon, M.T., 1989, Geology of the San Juan-Cascade Nappes, northwestern Cascade Range and San Juan Islands, in Joseph, N. L. (Ed.), Geologic Guidebook for Washington and Adjacent Areas: prepared for the 85th Annual Meeting of the Cordilleran Section, Geological Society of America, May 8-11, 1989, Spokane, Washington: Washington Division of Geology and Earth Resource Infomation Circular 86, p. 137-162.

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.

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.

NGMDB product
Counties Asotin - Ferry - Okanogan - San Juan