Skip to main content

Lacustrine and fluvial sedimentary rocks (Pleistocene)

Unconsolidated to semiconsolidated lacustrine clay, silt, sand, and gravel; in places includes mudflow and fluvial deposits and discontinuous layers of peat. Includes older alluvium and related deposits of Piper (1942), Willamette Silt (Allison, 1953; Wells and Peck, 1961), alluvial silt, sand, and gravel that form terrace deposits of Wells and others (1983), and Gresham and Estacada Formations of Trimble (1963). Includes deltaic gravel and sand and gravel bars, in pluvial lake basins in southeastern part of map area. In Rome Basin, includes discontinuous layers of poorly consolidated conglomerate characterized by well-rounded, commonly polished pebbles of chert and pebbles and cobbles of quartzite. In places contains mollusks or vertebrate fossils indicating Pleistocene age; mostly deposits of late Pleistocene age, but locally includes some deposits of early Holocene age. Includes Touchet Beds of Flint (1938), deposits of valley terraces of Newcomb (1965), and, in southeast Oregon, basin-filling deposits that incorporate Mazama ash deposits (Qma, Qmp) in the youngest layers
State Oregon
Name Lacustrine and fluvial sedimentary rocks (Pleistocene)
Geologic age Pleistocene
Primary rock type clay or mud
Secondary rock type silt
Other rock types sand; gravel
Lithologic constituents
Major
Sedimentary > Clastic > Mudstone > Claystone (Bed)Contains clay, silt, sand, gravel, mudflow, fluvial and eolian deposits, peat, sand and gravel bars in pluvial lakes, and conglomerate with clasts of chert and quartzite
Sedimentary > Clastic > Siltstone (Bed)
Minor
Sedimentary > Coal > Lignite (Bed)
Sedimentary > Clastic > Sandstone > Arenite (Bed)
Sedimentary > Clastic > Conglomerate (Bed)
Sedimentary > Clastic > Mixed-clastic (Deltaic)
Igneous > Volcanic > Felsic-volcanic > Rhyolite (Pyroclastic, air fall)Mazama ash
Map references
Walker, G.W. and MacLeod, N.S., 1991, Geologic map of Oregon: U.S. Geological Survey, scale 1:500,000.
Unit references
Walker, G.W. and MacLeod, N.S., 1991, Geologic map of Oregon: U.S. Geological Survey, scale 1:500,000.
Walker, G.W. and Repenning, C.A., 1966, Geologic map of the west half of the Jordan Valley quadrangle, Malheur County, Oregon: U.S. Geological Survey Miscellaneous Geologic Investigations Map I-457, scale 1:250,000.
Greene, R.C., Walker, G.W., and Corcoran, R.E., 1972, Geologic map of the Burns quadrangle, Oregon: U.S. Geological Survey Miscellaneous Geologic Investigations Map I-680, scale 1:250,000.
Walker, G.W. and Repenning, C.A., 1965, Geologic map of Adel quadrangle, Lake, Harney, and Malheur Counties, Oregon: U.S. Geological Survey Miscellaneous Geologic Investigations Map I-446, scale 1:250,000.
Ferns, M.L., Evans, J.G., and Cummings, M.L., 1993a, Geologic map of the Mahogany Mountain 30 x 60 minute quadrangle, Malheur County, Oregon: Oregon Department of Geology and Mineral Industries Geological Map Series GMS-78, scale 1:100,000.
Ferns, M.L., Brooks, H.C., Evans, J.G., and Cummings, M.L., 1993b, Geologic map of the Vale 30 x 60 minute quadrangle, Malheur County Oregon: Oregon Department of Geology and Mineral Industries Geological Map Series GMS-77, scale 1:100,000.
Swanson, D.A., 1969a, Reconnaissance geologic map of the east half of the Bend quadrangle, Crook, Wheeler, Jefferson, Wasco, , and Deschutes Counties, Oregon: U.S. Geological Survey Miscellaneous Geologic Investigations Map I-568, scale 1:250,000.
Walker, G.W., 1979, Reconnaissance geologic map of the Oregon part of the Grangeville quadrangle, Baker, Union, Umatilla, and Wallowa Counties, Oregon: U.S. Geological Survey Miscellaneous Geologic Investigations Map I-1116, scale 1;250,000
Walker, G.W., 1973, Reconnaissance geologic map of the Pendleton quadrangle, Oregon and Washington: U.S. Geological Survey Miscellaneus Geologic Investigations Map I-727, scale 1:250,000.
Walker, G.W., 1977, Geologic map of Oregon east of the 121st meridian: U.S. Geological Survey Miscellaneous Geologic Investigations Map I-902, scale 1:500,000.
Evans, J.G. and Binger, G.B., 1998, Geologic map of the Little Black Canyon quadrangle, Malheur County, Oregon: U.S. Geological Survey Open-File Report 98-493, scale 1:24,000.
Barrash, Warren, Bond, J.G., Kauffmann, J.D., and Venkatakrishnan, Ramesh, 1980, Geology of the La Grande area, Oregon: Oregon Department of Geology and Mineral Industries Special Paper 6, 67 p., 4 maps, scale 1:24,000.
Evans, J.G. and Binger, G.B., 1998, Geologic map of the Shumway Reservoir quadrangle, Malheur County, Oregon: U.S. Geological Survey Open-File Report 98-138, scale 1:24,000.
Evans, J.G. and Keith, W.J., 1996, Geologic map of the Tims Peak quadrangle, Malheur County, Oregon: U. S. Geological Survey Miscellaneous Field Studies Map MF-2316, scale 1:24,000.
Minor, S.A., Rytuba, J.J., Grubensky, M.J., Vander Meulen, D.B., Goeldner, C.A., and Tegtmeyer, K.J., 1987, Geologic map of the High Steens and Little Blitzen Gorge Wilderness Study Areas, Harney County, Oregon: U.S. Geological Surevy Miscellaneous Field Studies Map MF-1876, scale 1:24,000.
Evans, J.G., Rytuba, J.J., Binger, G.B., and Hooper, P.R., 1999, Preliminary geologic map of the Star Creek Reservoir quadrangle, Malheur County, Oregon: U.S. Geological Survey Open-File Report 99-583, scale 1:24,000.
Ferns, M.L., 1992, Preliminary geologic map of the Bogus Bench quadrangle, Malheur County, Oregon: Oregon Department of Geology and Mineral Industries Open-File Map O-92-02, scale 1:24,000.
Ferns, M.L., 1992, Preliminary geologic map of the Mustang Butte quadrangle, Malheur County, Oregon: Oregon Department of Geology and Mineral Industries Open-File Map O-92-11, scale 1:24,000.
Ferns, M.L., 1992, Preliminary geologic map of the Sacramento Butte quadrangle, Malheur County, Oregon: Oregon Department of Geology and Mineral Industries Open-File Map O-92-13, scale 1;24,000.
Ferns, M.L., 1992, Preliminary geologic map of the Saddle Butte quadrangle, Malheur County, Oregon: Oregon Department of Geology and Mineral Industries Open-File Map O-92-14, scale 1:24,000.
Ferns, M.L. and Williams, C.P., 1993, Preliminary geologic map of the Burnt Flat quadrangle, Malheur County, Oregon: Oregon Department of Geology and Mineral Industries Open-File Map O-93-2, scale 1:24,000.
Ferns, M.L. and Williams, C.P., 1993, Preliminary geologic map of the Crowley quadrangle, Malheur County, Oregon: Oregon Department of Geology and Mineral Industries Open-File Map O-93-04, scale 1:24,000.
Minor, S.A., Rytuba, J.J., Goeldner, C.A., and Tegtmeyer, K.J., 1987, Geologic map of the Alvord Hot Spring quadrangle, Harney County, Oregon: U.S. Geological Survey Miscellaneous Field Studies Map MF-1916, scale 1:24,000.
Minor, S.A., Vander Meulen, D.B., Rytuba, J.J., and Vercoutere, T.L., 1989, Geologic map of The V quadrangle, Harney County, Oregon: U.S. Geological Survey Open-File Report 89-351, scale 1:24,000.
Camp, V.E., Ross, M.E., and Hanson, W.E., 2003, Genesis of flood basalts and Basin and Range volcanic rocks from Steens Mountain to the Malheur River Gorge, Oregon: Geological Society of America Bulletin, v. 115, no. 1, p. 105-128.
Rytuba, J.J., Vander Meulen, D.B., Vercoutere, T.L., and Minor, S.A., 1982b, Reconnaissance geologic map of the Borax Lake quadrangle, Harney County, Oregon: U.S. Geological Survey Open-File Report 82-1126, scale 1:24,000.
Evans, J.G., unpub. mapping, 1994, Fields quadrangle, Harney County
Evans, J.G., unpub. mapping, 1994, Ladycomb Peak quadrangle, Harney County
Johnson, J.A., 1995, Geologic evolution of the Duck Butte eruptive center, High Lava Plains, southeastern Oregon: Corvallis, Oregon State University, master's thesis, 151 p.
Johnson, J.A. and Grunder, A.l., 2000, The making of intermediate compositional magma in a bimodal suite: Duck Butte eruptive center, Oregon, USA: Journal of Volcanology and Geothermal Research, v. 95, p. 175-195.
Minor, S.A., Rytuba, J.J., and Vercoutere, T.L., 1989, Geologic map of the Windy Point quadrangle, Harney County, Oregon: U.S. Geological Survey Open File Report 89-212, scale 1:24,000.
Minor, S.A., Vander Meulen, D.B., Rytuba, J.J., and Vercoutere, T.L., 1989, Geologic map of The V quadrangle, Harney County, Oregon: U.S. Geological Survey Open-File Report 89-351, scale 1:24,000.
Rytuba, J.J., Minor, S.A., Conrad, W.K., and Vander Meulen, D.B., 1982, Geologic map of the Trout Creek Canyon quadrangle, Harney County, Oregon: U.S. Geological Survey Open-File Report 82-281, scale 1:24,000.
Rytuba, J.J., Minor, S.A., Miller, R.J., and Vander Meulen, D.B., 1983, Geologic map of the Red Lookout Butte quadrangle, Harney County, Oregon: U.S. Geological Survey Open-File Report 83-0283, scale 1:24,000.
Wood, J.D., 1976, The geology of the Castle Rock area, Grant, Harney, and Malheur Counties, Oregon: Portland, Oregon, Portland State University, master's thesis, 89 p.
Ferns, M.L., Madin, I.P., and Taubeneck, W.H., 2001, Reconnaissance geologic map of the La Grande 30' x 60' quadrangle, Baker, Grant, Umatilla, and Union Counties, Oregon: Oregon Department of Geology and Mineral Industries Reconnaissance Map Series RMS-1, 52 p., scale 1:100,000.
Ferns, M.L. and Madin, I.P., 1999, Geologic map of the Summerville quadrangle, Union County, Oregon: Oregon Department of Geology and Mineral Industries Geological Map Series GMS-111, scale 1:24,000.
Ferns, M.L., McConnell, V.S., Madin, I.p., and Van Tassell, 2002, Geology of the Imbler quadrangle, Union County, Oregon: Oregon Department of Geology and Mineral Industries Geological Map Series GMS-114, scale 1:24,000.
Counties Benton - Clackamas - Columbia - Crook - Curry - Deschutes - Gilliam - Grant - Harney - Hood River - Jefferson - Klamath - Lake - Lane - Lincoln - Linn - Malheur - Marion - Multnomah - Polk - Umatilla - Union - Wallowa - Wasco - Washington - Yamhill