Upper Eocene volcanic rocks

Predominantly andesite flows and breccia; includes some basalt flows. Contains basaltic conglomerate, pyroclastic rocks, tuff beds, and sandstone in Chehalis-Centralia coal district, Lewis County.
State Washington
Name Upper Eocene volcanic rocks
Geologic age Late Eocene
Lithologic constituents
Igneous > Volcanic > Mafic-volcanic > Andesite (Flow, Pyroclastic, Volcaniclastic-volcanic breccia)
Igneous > Volcanic > Mafic-volcanic > Basaltic-andesite (Flow)
Igneous > Volcanic > Mafic-volcanic > Basalt (Flow, Pyroclastic, Volcaniclastic-volcanic breccia)
Sedimentary > Clastic > Siltstone (Tuffaceous)
Sedimentary > Clastic > Conglomerate (Bed)
Sedimentary > Clastic > Sandstone (Tuffaceous)
Sedimentary > Clastic > Mudstone (Tuffaceous)
Comments The Northcraft formation is 680-1400 ft thick (Snavely and others, 1958).
Stratigraphic units Northcraft formation

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.


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.

Snavely, P.D.,Jr., Brown, R.D., Roberts, A.E., Rau, W.W., 1958, Geology and Coal Resources of the Centralia-Chelalis District, Washington: U. S. Geological Survey Bulletin 1053, 149 p.

NGMDB product
Counties King - Lewis - Pierce - Thurston