Miocene-Pliocene nonmarine rocks

Tuffaceous and pumiceous andesitic sandstone and siltstone with interbedded conglomerate and claystone. Conglomerate beds chiefly andesitic, but also quartzitic, granitic, and basaltic; includes basalt flows locally.
State Washington
Name Miocene-Pliocene nonmarine rocks
Geologic age Miocene-Pliocene
Lithologic constituents
Igneous > Volcanic (Pyroclastic-air fall)Pumicite of Beverly Member; may also be described as pumiceous sandstone or siltstone.
Sedimentary > Clastic > Conglomerate (Bed)
Unconsolidated > Coarse-detrital > Gravel (Fluvial)Mostly basaltic.
Unconsolidated (Mass wasting)Laharic deposits.
Unconsolidated > Coarse-detrital > Sand (Fluvial)Mostly basaltic. Possibly consolidated to sandstone in some areas.
Igneous > Volcanic > Mafic-volcanic > Basalt (Flow)
Comments Ellensburg formation also described as fluvial and laharic gravel, sand, silt, and clay. Thorp gravel is coarse sand and gravel conformably and unconformably overlying the Ellensburg formation (Bentley and Campbell, 1983). Mackin, 1961, considers the Saddle Mountain Basalt Member to be part of the Ellensburg Formation; local basalt flows are probably of this type (or of the Beverly Member) though most of the Saddle Mountain Basalt Member is part of unit WAMPLv.
Stratigraphic units Ellensburg Formation: Beverly Member, Vantage Member; Thorp gravel

Huntting, M.T., Bennett, W.A.G., Livingston, V.E.Jr., and Moen, W.S., 1961, Geologic Map of Washington: Washington Division of Mines and Geology, scale 1:500,000.

Schuster, J.E., Gulick, C.W., Reidel, S.P., Fecht, K.R., Zurenko, S., 1997, Geologic Map of Washington--Southeast Quadrant: Washington Division of Geology and Earth Resources Geologic Map GM-45, scale 1:250,000.

Walsh, T.J., Korosec, M.A., Phillips, W.M., Logan, R.T., Schasse, H.W., 1987, Geologic Map of Washington-Southwest Quadrant: Washington Division of Geology and Earth Resources, Geologic Map GM-34, scale 1:250,000.

Warren, W.C., 1941, Relation of the Yakima Basalt to the Keechelus Andesite Series: The Journal of Geology, v. 49, p. 795-814.

Tabor, R.W., Waitt, R.B.,Jr., Frizzell, V.A.,Jr., Swanson, D.A., Byerly, G.R., Bentley, R.D., 1982, Geologic Map of the Wanatchee 1:100,000 Quadrangle, Central Washington: U. S. Geological Survey Miscellaneous Investigations Series Map I-1311, scale 1:100,000.

Bentley, R.D. and Campbell, N.P., 1983, Geologic Map of the Yakima Quadrangle, Washington: Washington Division of Geology and Earth Resources Geologic Map GM-29, scale 1:62,500.

Smith, G.A., Shafiquillah, M., Campbell, N.P., Deacon, M.W., 1989, Geochronology of the Ellensburg Formation--Constraints on Neogene Volcanism and Stratigraphic Relationships in Central Washington: Isochron/West, v. 53, p. 28-32.

Mackin, J.H., 1961, A Stratigraphic Section in the Yakima Basalt and the Ellensburg Formation in South-Central Washington: Washington Division of Mines and Geology Report of Investigations no.19, 45 p.

Grolier, M.J. and Bingham, J.W., 1971, Geologic Map and Sections of Parts of Grant, Adams, and Franklin Counties, Washington: U. S. Geological Survey Miscellaneous Geologic Investigations Map I-589, 6 pls., scale 1:62,500.

NGMDB product
Counties Adams - Benton - Douglas - Grant - Kittitas - Klickitat - Yakima