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Marine siltstone, sandstone, and conglomerate (lower Eocene)

Cobble and pebble conglomerate, pebbly sandstone, lithic sandstone, siltstone, and mudstone; massive to thin bedded; shelf and slope depositional setting. Contains foraminiferal faunas referred to the Penutian Stage of early Eocene age. Included by Diller (1898) in the Umpqua Formation; Baldwin (1974) and Ryberg (1984) included it in the Lookingglass Formation of the Umpqua Group of Baldwin; may be partly a shelf and slope facies of the sedimentary rocks of the Roseburg Formation of Baldwin (1974) according to Molenaar (1985) and Heller and Ryberg (1983)
State Oregon
Name Marine siltstone, sandstone, and conglomerate (lower Eocene)
Geologic age Early Eocene
Primary rock type siltstone
Secondary rock type sandstone
Other rock types mudstone; conglomerate
Lithologic constituents
Major
Sedimentary > Clastic > Siltstone (Bed)
Sedimentary > Clastic > Sandstone (Bed)
Sedimentary > Clastic > Mudstone (Bed)
Minor
Sedimentary > Clastic
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.
Diller, J.S., 1898, Roseburg [quadrangle], Oregon, folio 49 of the Geologic Atlas of the United States: U.S. Geological Survey, scale 1:125,000.
Baldwin, E.M., 1974, Eocene stratigraphy of southwestern Oregon: Oregon Department of Geology and Mineral Industries Bulletin 83, 40 p.
Ryberg, P.T., 1984, Sedimentation, structure and tectonics of Umpqua Group (Paleocene to Early Eocene), southwestern Oregon: Tucson, Arizona, University of Arizona, Ph.D. dissertation, 280 p.
Molenaar, C.M., 1985, Depositional relations of Umpqua and Tyee Formations (Eocene), southwest Oregon: American Association of Petroleum Geologists Bulletin, v. 69, p. 1217-1229.
Heller, P.L., and Ryberg, P.T., 1983, Sedimentary record of subduction to forearc transition in the rotated Eocene basin of western Oregon: Geology, v. 11, p. 380-383.
Counties Coos - Curry - Douglas