Porphyritic basalt (ORTpb;0)

Porphyritic basalt

Subaerial lava flows and breccia of porphyritic basalt, minor basaltic andesite, and rare dacite. Includes basalt of Cascade Head (Wells and others, 1983), Yachats Basalt (Snavely and others, 1976c) and Goble Volcanic Series (Warren and others, 1945). Also includes camptonitic extrusive rocks (tuff breccia, lapilli tuff, and minor pillow flows) interbedded in Nestucca Formation

State	Oregon
Name	Porphyritic basalt
Geologic age	Late Eocene
Lithologic constituents	Major Igneous > Volcanic > Mafic-volcanic > Basalt (Flow, Volcaniclastic-volcanic breccia) Minor Igneous > Volcanic > Mafic-volcanic > Basaltic-andesite (Dome, Volcaniclastic-volcanic breccia) Incidental Igneous > Volcanic > Felsic-volcanic > Dacite (Flow, Volcaniclastic-volcanic breccia)
References	Walker, G.W. and MacLeod, N.S., 1991, Geologic map of Oregon: U.S. Geological Survey, scale 1:500,000. Wells, R.E., Niem, A.R., MacLeod, N.S., Snavely P.D., Jr., and Niem, W.A., 1983, Preliminary geologic map of the west half of the Vancouver (Washington-Oregon) 1ø by 2ø quadrangle: U.S. Geological Survey Open-File Report 83-591, scale 1:250,000. https://pubs.er.usgs.gov/publication/ofr83591 Snavely, P.D., Jr., MacLeod, N.S., Wagner, H.C., and Rau, W.W., 1976c, Geologic map of the Waldport and Tidewater quadrangles, Lincoln, Lane, and Benton Counties, Oregon: U.S. Geological Survey Miscellaneous Investigations Series Map I-866, scale 1:62,500. https://pubs.er.usgs.gov/publication/i866 Warren, W.C., Norbisrath, H., and Grivetti, R.M., 1945, Geology of northwestern Oregon: U.S. Geological Survey Oil and gas Investigations Preliminary Map 42, scale 1:190,000. https://pubs.er.usgs.gov/publication/om42
NGMDB product	NGMDB product page for 16259
Counties	Columbia - Lane - Lincoln - Tillamook

Porphyritic basalt

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

Wells, R.E., Niem, A.R., MacLeod, N.S., Snavely P.D., Jr., and Niem, W.A., 1983, Preliminary geologic map of the west half of the Vancouver (Washington-Oregon) 1ø by 2ø quadrangle: U.S. Geological Survey Open-File Report 83-591, scale 1:250,000.

Snavely, P.D., Jr., MacLeod, N.S., Wagner, H.C., and Rau, W.W., 1976c, Geologic map of the Waldport and Tidewater quadrangles, Lincoln, Lane, and Benton Counties, Oregon: U.S. Geological Survey Miscellaneous Investigations Series Map I-866, scale 1:62,500.

Warren, W.C., Norbisrath, H., and Grivetti, R.M., 1945, Geology of northwestern Oregon: U.S. Geological Survey Oil and gas Investigations Preliminary Map 42, scale 1:190,000.