Marine sedimentary rocks (lower Miocene and Oligocene) (ORTsm;0)

Fossiliferous marine tuffaceous arkosic sandstone, and lesser conglomerate, sandstone, claystone, nonmarine volcanic sedimentary rocks, and minor coal. Molluscan and vertebrate (Cetacea) fossils indicate late Oligocene and Miocene age (Orr and Miller, 1983; Miller and Orr, 1984b). Includes Butte Creek beds of Harper (1946), and several Miocene and late Oligocene units of Miller and Orr (1984a, b)

State	Oregon
Name	Marine sedimentary rocks (lower Miocene and Oligocene)
Geologic age	Oligocene to Early Miocene
Original map label	Tsm
Primary rock type	sandstone
Secondary rock type	conglomerate
Other rock types	claystone; coal
Lithologic constituents	Major Sedimentary > Clastic > Sandstone (Bed) Minor Sedimentary > Clastic > Mudstone > Claystone (Bed) Sedimentary > Clastic > Conglomerate (Bed) Incidental Sedimentary > Coal (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. Orr, W.N., and Miller, P.R., 1983, Fossil Cetaceae (whales) in the Western Cascades: Oregon Geology, v. 45, p. 95-98. Miller, P.R., and Orr, W.N., 1984a, Geologic map of the Wilhoit quadrangle, Oregon: Oregon Department of Geologyand Mineral Industries Geologic Map Series GMS032, scale 1:24,000. Miller, P.R., and Orr, W.N., 1984b, Geologic map of the Scotts Mills quadrangle, Oregon: Oregon Department of Geologyand Mineral Industries Geologic Map Series GMS033, scale 1:24,000. Harper, H.E., 1946, Preliminary report on the geology of the Molalla quadrangle: Corvallis, Oregon, Oregon State University, M.S. thesis, 28 p.
Geographic coverage	Clackamas - Marion