Precambrian conglomerate

Gray-brown, coarse, poorly sorted pebbles and cobbles of limestone, dolomite, reddish-brown quartzite, black slate or phyllite, and rarely granitic rocks in a gray sandy phyllite matrix; northeastern Pend Oreille County and southwestern Stevens County. Rocks become finer grained and more schistose and the unit becomes thicker toward the southwest, where there is included an isolated subunit which may be a tillite, consisting of cobbles, boulders, and blocks of argillite and carbonate rocks in a fine silty matrix.
State Washington
Name Precambrian conglomerate
Geologic age Late-Proterozoic
Lithologic constituents
Sedimentary > Clastic > Conglomerate (Bed)Includes meta-conglomerate.
Metamorphic > Metasedimentary > Metaclastic > PhylliteRank based on mapping by Joseph, 1990a, b.
Sedimentary > Carbonate > Dolostone (Bed)Possibly occurrance of limestone as well (Joseph, 1990a, b).
Sedimentary > Clastic > Sandstone (Bed)
Metamorphic > Metasedimentary > Metaclastic > Quartzite
Metamorphic > Metaigneous > Greenstone (Greenschist)
Metamorphic > Schist
Stratigraphic units Windermere Group: Huckleberry Formation (in part: conglomerate member), Shedroof conglomerate

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.

Park, C.F.Jr., and Cannon, R.S.Jr., 1943, Geology and Ore Deposits of the Metaline Quadrangle, Washington: U. S. Geological Survey Professional Paper 202, 81 p.

Stoffel, K.L., Joseph, N.L., Waggoner, S.Z., Gulick, C.W., Korosec, M.A., Bunning, B.B., 1991, Geologic Map of Washington--Northeast Quadrant: Washington Division of Geology and Earth Resources Geologic Map, GM-39, scale 1:250,000.

Joseph, N.L., 1990a, Geologic Map of the Colville 1:100,000 Quadrangle, Washington-Idaho: Washington Division of Geology and Earth Resources Open File Report 90-13, 78 p., 1 pl.

Joseph, N.L., 1990b, Geologic Map of the Nespelem 1:100,000 Quadrangle, Washington: Washington Division of Geology and Earth Resources Open File Report 90-16, 47 p., 1 pl.

NGMDB product
Counties Pend Oreille - Stevens