Marine sandstone and siltstone (middle Eocene) (ORTmss;0)

Thin- to thick-bedded, crossbedded, well-sorted, fine- to medium-grain sandstone, siltstone, and mudstone; characterized by sparse fine white mica; shallow marine depositional setting at least partly of deltaic origin. Contains foraminiferal and molluscan faunas of early middle Eocene age. Included by Diller (1898) in the upper part of the Umpqua Formation, by Baldwin (1974) and Ryberg (1984) in the Flournoy Formation of the Umpqua Group, and by Molenaar (1985) in Camas Valley and the White Tail Ridge Members of Baldwin (1974) of the Umpqua Formation

State	Oregon
Name	Marine sandstone and siltstone (middle Eocene)
Geologic age	Middle Eocene
Original map label	Tmss
Primary rock type	sandstone
Secondary rock type	siltstone
Other rock types	mudstone
Lithologic constituents	Major Sedimentary > Clastic > Sandstone (Bed) Minor Sedimentary > Clastic > Mudstone (Bed) Sedimentary > Clastic > Siltstone (Bed)
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. [http://pubs.er.usgs.gov/publication/gf49] 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.
Geographic coverage	Baker - Coos - Curry - Douglas - Josephine