Cowlitz Formation

Micaceous, arkosic to basaltic marine sandstone, siltstone, and mudstone. Foraminiferal assemblages are referred to the upper Narizian Stage of Mallory (1959) in Newton and Van Atta (1976)
State Oregon
Name Cowlitz Formation
Geologic age Middle Eocene to Late Eocene
Lithologic constituents
Major
Sedimentary > Clastic > Sandstone (Bed)
Sedimentary > Clastic > Siltstone (Bed)
Minor
Sedimentary > Clastic > Mudstone (Bed)
References

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

Mallory, V.S., 1959, Lower Tertiary biostratigraphy of the California Coast Ranges: Tulsa, Oklahoma, American Association of Petroleum Geologists, 416 p.

Newton, V.C. and Van Atta, R.O., 1976, Prospects for natural gas production and underground storage of pipe-line gas in the upper Nehalem River Basin, Columbia-Clatsop Counties, Oregon: Oregon Department of Geology and Mineral Industries Oil and Gas Investigations 5, 56 p.

NGMDB product
Counties Clatsop - Columbia - Tillamook - Washington