Upper Eocene volcanic rocks

Andesite and basalt flows and associated breccia in central Lewis County. Pyroclastic rocks, mudflows, flow breccia, and volcanic-rich sedimentary rocks in King and Pierce Counties.
State Washington
Name Upper Eocene volcanic rocks
Geologic age Late Eocene
Lithologic constituents
Igneous > Volcanic > Mafic-volcanic > Andesite (Flow, Volcaniclastic-volcanic breccia, Pyroclastic-tuff)
Igneous > Volcanic > Mafic-volcanic > Basalt (Flow)
Sedimentary > Clastic > Siltstone (Bed)
Sedimentary > Clastic > Sandstone (Bed)Volcanic and feldspathic.
Sedimentary > Clastic > Conglomerate (Bed)Conglomerate of mudflow origin dominates.
Stratigraphic units Northcraft formation (in part)

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.

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.

Luedke, Robert G., 1998, Maps showing distribution, composition, and age of Early and Middle Cenozoic volcanic centers in Oregon and Washington: U.S. Geological Survey Miscellaneous Investigations Series Map I-2291-D, scale 1:1,000,000.


Smith, J.G., 1993, Geologic Map of Upper Eocene to Holocene Volcanic and Related Rocks in the Cascade Range, Washington; U. S. Geological Survey Miscellaneous Investigations Series Map I-2005, scale 1:500,000.

Roberts, A.E., 1958, Geology and Coal Resources of the Toledo-Castle Rock District, Cowlitz and Lewis Counties, Washington: U. S. Geological Survey Bulletin 1062, 71 p, 6 pls.

NGMDB product
Counties King - Lewis - Pacific - Pierce - Thurston