Tuffaceous siltstone and sandstone

Thick- to thin-bedded marine tuffaceous mudstone, siltstone, and sandstone; fine to coarse grained. Contains calcareous concretions and, in places, is carbonaceous and micaceous. Includes the Nestucca Formation, which contains a foraminiferal assemblage assigned to the upper Narizian and lowermost Refugian Stages (Snavely and others, 1969; McKeel, 1980); the Spencer Formation, which contains Narizian Stage foraminifers; the Keasey Formation, which contains upper Narizian and lower Refugian Stage foraminifers (McDougall, 1975, 1980); the Coaledo and Bateman Formations of Baldwin (1974); upper Eocene sandstone of Bela (1981); and the Sager Creek formation (informal name) of Niem and Niem (1985)
State Oregon
Name Tuffaceous siltstone and sandstone
Geologic age Middle Eocene to Late Eocene
Lithologic constituents
Sedimentary > Clastic > Mudstone (Bed)
Sedimentary > Clastic > Siltstone (Bed)
Sedimentary > Clastic > Sandstone (Bed)

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

Snavely, P.D., Jr., McLeod, N.S., and Rau, w.w., 1969, Geology of the Newport area, Oregon: The Ore Bin, v. 31, p. 25-71.

McKeel, D.R., 1980, Micropaleontological study of five wells, western Willamette Valley, Oregon: Oregon Department of Geology and Mineral Industries Open-File Report 0-80-1, 21 p.

McDougall, K., 1975, The microfauna of the type section of the Keasey Formation of Northwestern Oregon, in Weaver, D.W., Hornaday, G.R., and Tipton, A., eds., Future energy horizons of the Pacific Coast: Society of Economic Paleontologists and Mineralogists, Pacific Section, Long Beach, California, 1975, p. 343-359.

Baldwin, E.M., 1974, Eocene stratigraphy of southwestern Oregon: Oregon Department of Geology and Mineral Industries Bulletin 83, 40 p.

Bela, J.L., 1981, Geology of the Rickreall, Salem West, Monmouth, and Sidney 7-1/2 ' quadrangles, Marion, Polk, and Linn Counties, Oregon: Oregon Department of Geology and Mineral Industries Geologic Map Series GMS-18, scale 1:24,000.

Niem, A.R., and Niem, W.A., 1985, Oil and tgas investigation of the Astoria Basin, Clatsop and northernmost Tillamook Counties, northwest Oregon: Oregon Department of Geology and Mineral Industries Oil and Gas Investigation OGI-14, scale 1:100,000.

NGMDB product
Counties Benton - Clatsop - Columbia - Coos - Douglas - Lane - Lincoln - Linn - Marion - Polk - Tillamook - Washington - Yamhill