Sedimentary rocks

Semiconsolidated lacustrine and fluvial ashy and palagonitic sedimentary rocks, mostly tuffaceous sandstone and siltstone; locally contains abundant palagonitized basaltic debris and some pebble conglomerate. Includes alluvial gravel and mudflow deposits of Walters Hill and Springwater Formations (Trimble, 1963). In places, grades laterally through palagonite tuff and breccia into basalt flows
State Oregon
Name Sedimentary rocks
Geologic age Pliocene to Pleistocene
Lithologic constituents
Major
Sedimentary > Clastic > Mixed-clastic > Sandstone-mudstone (Bed)
Minor
Sedimentary > Clastic > Conglomerate (Bed)
References

Walker, G.W. and MacLeod, N.S., 1991, Geologic map of Oregon: U.S. Geological Survey, scale 1:500,000.

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.

https://pubs.er.usgs.gov/publication/i902

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 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. and Evans, J.G., 1993c, Preliminary geologic map of the Rinehart Canyon quadrangle, Malheur County, Oregon: Oregon Department of Geology and Mineral Industries Open-File Map O-93-5, 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.

Plumley, P.S., 1986, Volcanic stratigraphy and geochemistry of the Hole in the Ground area, Owyhee Plateau, southeastern Oregon: Moscow, University of Idaho, master's thesis, 161 p.

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Counties Clackamas - Crook - Deschutes - Harney - Jefferson - Klamath - Lake - Lane - Malheur - Marion - Morrow - Multnomah - Wasco - Washington - Yamhill