Precambrian rocks, undivided

Predominantly phyllite with some schist, limestone, dolomite, quartzite, and volcanic rocks; northeastern Pend Oreille County. Mainly quartzite sandstone in upper part, dark-gray argillite with sandstone and limestone in middle part, and sandstone with argillite in lower part; southeastern Pend Oreille County. Banded slate with quartzite and dolomite; southwestern Stevens County. Quartzite, siliceous argillite, and argilliceous quartzite grading into argillite and quartz-mica schists form south ot north; southeastern Stevens County. Quartzite, argillite, quartz-feldspar gneiss, and other metamorphic rocks in northeastern Whitman and southeastern Spokane Counties are partly if not all extenstions of the Belt strata.
State Washington
Name Precambrian rocks, undivided
Geologic age Proterozoic
Lithologic constituents
Major
Sedimentary > Clastic > Siltstone (Bed)Often referred to as siltite.
Metamorphic > Metasedimentary > Metaclastic > Argillite
Minor
Metamorphic > Metasedimentary > Metaclastic > Quartzite
Sedimentary > Carbonate > Dolostone (Bed)
Metamorphic > Metasedimentary > Metaclastic > PhyllitePossibly only incidental in rank.
Incidental
Sedimentary > Carbonate > Limestone (Bed)
Metamorphic > GneissLocated near Spokane on the Washington-Idaho border; considered a part of the Prichard Formation (Griggs, 1973).
Sedimentary > Clastic > Sandstone (Bed)
Metamorphic > Schist
Stratigraphic units Belt Supergroup (Striped Peak Formation, Wallace Formation, Ravalli Group, Prichard Formation); Deer Trail Group (Edna Dolomite, McHale Shale, Togo Formation, Buffalo Hump Fomation); Priest River Group; No Name Argillite; Skookum Formation; Bead Lake Formation; Windermere Supergroup (in small part: mostly mapped as units WAPCc (Huckleberry Formation), WAPCv (Huckleberry Foramation), and WAPCph (Monk Formation and Three Sisters Formation)); Maitlen Phyllite (in part)
References

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.

Weis, P.L., 1968, Geologic Map of the Greenacres Quadrangle, Washington and Idaho: U. S. Geologic Quadrangle Maps of the United States Map GQ-734, scale 1:62,500.

Campbell, I. and Loofbourow, J.S.Jr., 1962, Geology of the Magnesite Belt of Stevens County Washington, U. S. Geological Survey Bulletin 1142-F, F1-F53 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.

Schroeder, M.C., 1952, Geology of the Bead Lake District, Pend Oreille County, Washington: Washington Division of Mines and Geology Bulletin No. 40, 57 p.

Griggs, A.B., 1973, Geologic Map of the Spokane Quadrangle, Washington, Idaho, and Montana: U. S. Geological Survey Miscellaneous Geologic Investigations Map I-768, 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.

Waggoner, S.Z., 1990b, Geologic Map of the Chewelah 1:100,000 Quadrangle, Washington-Idaho: Washington Division of Geology and Earth Resources Open File Report 90-14, 63 p., 1 pl.

NGMDB product
Counties Pend Oreille - Spokane - Stevens - Whitman