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Tuff, arkose, claystone, siltstone, conglomerate, lignite; Miocene alluvial and lacustrine deposits

Miocene stream and lake deposits; generally associated with volcanic episodes.
State Idaho
Name Tuff, arkose, claystone, siltstone, conglomerate, lignite; Miocene alluvial and lacustrine deposits
Geologic age Miocene
Comments Tmd consists of semi-consolidated tuffaceous clastic sediments and incidental deposits of clay and lignite. Payette Fm is exposed between Weiser and Cambridge, Idaho, as well as in smaller valleys. Sucker Creek Fm is in the Owyhee Mountains. Latah Fm is interlayered with Columbia River Basalt flows in western Idaho.
Primary rock type tuff
Secondary rock type arkose
Other rock types claystone; conglomerate; siltstone; mixed clastic/coal
Lithologic constituents
Major
Igneous > Volcanic (Pyroclastic, tuff)tuff and tuffaceous clastic sediments, semi-consolidated
Minor
Sedimentary > Clastic > Sandstone > Arkose (Bed)alluvial to lacustrine
Sedimentary > Clastic > Mudstone > Claystone (Bed)lacustrine, derived from laterite and weathered volcanic ash
Incidental
Sedimentary > Clastic > Mudstone > Shale (Bed)lacustrine
Sedimentary > Clastic > Conglomerate (Bed)alluvial
Sedimentary > Clastic > Siltstone (Bed)alluvial to lacustrine
Sedimentary > Coal > Lignite (Bed)impure lignite in Payette Fm
Map references
Bond, J.G., Kauffman, J.D., Miller, D.A., and Venkatakrishnan, Ramesh, 1978, Geologic map of Idaho: Moscow, Idaho, Idaho Bureau of Mines and Geology, with contributions from U.S. Geological Survey, scale 1:500,000.
Unit references
Bond, J.G., Kauffman, J.D., Miller, D.A., and Venkatakrishnan, Ramesh, 1978, Geologic map of Idaho: Moscow, Idaho, Idaho Bureau of Mines and Geology, with contributions from U.S. Geological Survey, scale 1:500,000.
Alt, David, and Hyndman, D.W., 1995, Northwest Exposures, a Geologic Story of the Northwest: Missoula Montana, Mountain Press Publishing Co., 443 p.
Lindgren, Waldemar, 1898, The mining districts of the Idaho Basin and the Boise Ridge, Idaho, with a report on the fossil plants of the Payette formation by F.H., Knowlton: U.S. Geological survey Annual report 18, pt. 3, p. 617-744.
Mitchell, V.E., and Bennett, E.H., 1979, Geologic map of the Boise quadrangle, Idaho: Moscow, Idaho, Idaho Bureau of Mines and Geology, Geologic Map Series, Boise 2o Quadrangle, scale 1:250,000.
Mitchell, V.E. and Bennett, E.H., Geologic map of the Baker quadrangle, Idaho: Moscow, Idaho, Idaho Bureau of Mines and Geology, Geologic Map Series, Baker 2o Quadrangle, scale 1:250,000.
Counties Ada - Adams - Boise - Cassia - Clark - Gem - Idaho - Latah - Owyhee - Payette - Washington