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Sedimentary rocks (Jurassic and Upper Triassic)

Black, dark-gray, and dark -brownish-gray, thin-bedded siliceous or limy mudstone mostly consists of the Hurwal Formation in the Wallowa Mountains. In lower and middle parts contains Triassic fossils and in upper part Early Jurassic fossils (Nolf, 1966). Contact metamorphosed adjacent to Wallowa batholith
State Oregon
Name Sedimentary rocks (Jurassic and Upper Triassic)
Geologic age Triassic to Jurassic
Comments Metamorphosed equivalent rocks may be in the Mountain Home Metamorphic Complex (OR291; OR292)
Primary rock type mudstone
Secondary rock type
Other rock types
Lithologic constituents
Major
Sedimentary > Clastic > Mudstone (Bed)Siliceous or limy mudstone; includes Hurwal Formation in Wallowa Mountains
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.
Brown, C.E. and Thayer, T.P., 1966, Geologic map of the Canyon City quadrangle, northeastern Oregon: U.S. Geological Survey Miscellaneous Geologic Investigations Map I-447, scale 1:250,000.
Dickinson, W.R. and Vigrass, L.W., 1965, Geology of the Suplee-Izee area, Crook, Grant, and Harney Counties, Oregon: Oregon Department of Geology and Mineral Industries Bulletin 58, 109 p.
Brooks, H.C., McIntyre, J.R., and Walker, G.W., 1976, Geology of the Oregon part of the Baker 1o by 2o quadrangle: Oregon Department of Geology and Mineral Industries Geologic Map Series GMS-7, 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., 1977, Geologic map of Oregon east of the 121st meridian: U.S. Geological Survey Miscellaneous Geologic Investigations Map I-902, scale 1:500,000.
Nolf, Bruce, 1966, Structure and stratigraphy of part of the northern Wallowa Mountains, northeast Oregon: Princeton, N.J., Princeton University, Ph.D. dissertation, 193 p.
Vallier, T.L., 1977, the Permian and Triassic Seven Devils Group, western Idaho and northeast Oregon: U.S. Geological Survey Bulletin 1437, 58 p.
Wells, F.G. and Peck, D.L., 1961, Geologic map of Oregon west of the 121st meridian: U.S. Geological Survey Miscellaneous Geologic Investigations Map I-325, scale 1:500,000.
Wolff, E.N., 1965, The geology of the northern half of the Caviness quadrangle, Oregon: Eugene, University of Oregon, Ph.D. dissertation, 214 p.
Brooks, H.C., 2006, Preliminary geologic map of the Mormon Basin quadrangle, Baker County, Oregon: Oregon Department of Geology and Mineral Industries Open-File Map O-06-25, scale 1:24,000.
Swisher, C.C., Ach, J.A., and Hart, W.K., 1990, Laser fusion 40Ar/39Ar dating of the type Steens Mountain Basalt, southeastern Oregon, and the age of the Steens aeromagnetic polarity transition [abs.]: EOS, Transactions of American Geophysical Union, v. 17, no. 43, p. 1,296.
Beeson, J.H., Geology of the southern half of the Huntington quadrangle, Oregon: Eugene, University of Oregon, master's thesis, 77 p.
Berry, N.J., 1956, Geology of the northeast quarter of the Huntington quadrangle, Oregon: Eugene, University of Oregon, master's thesis, 78 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., McConnell, V.S., and Madin, I.P., in prep., Geology of the Umatilla River Basin, Morrow, Umatilla, and Union Counties, Oregon: Oregon Department of Geology and Mineral Industries Open-File Report, 66 p., scale 1:100,000.
Weiss, P.L., Gualtieri,, J.L., Cannon, W.F., Tucher, E.T., McMahan, A.B., and Federspiel, F.E., 1976, Mineral resources of the Eagle Cap Wilderness and adjacent areas, Oregon: U.S. Geological Survey Bulletin 1385-E, 100 p.
Counties Baker - Malheur - Union - Wallowa