Pyroclastic ejecta of basaltic cinder cones (lower Pliocene? and Miocene?) (ORTp;0)

State	Oregon
Name	Pyroclastic ejecta of basaltic cinder cones (lower Pliocene? and Miocene?)
Geologic age	Miocene to Early Pliocene
Original map label	Tp
Primary rock type	basalt
Secondary rock type	andesite
Other rock types
Lithologic constituents	Major Igneous > Volcanic > Mafic-volcanic > Basalt (Pyroclastic)Also contains andesite Minor Igneous > Volcanic > Mafic-volcanic > Andesite (Pyroclastic, air fall) Igneous > Volcanic > Mafic-volcanic > Basalt (Pyroclastic, air fall) Igneous > Volcanic > Mafic-volcanic > Andesite (Pyroclastic)
Map references	Walker, G.W. and MacLeod, N.S., 1991, Geologic map of Oregon: U.S. Geological Survey, scale 1:500,000.
Unit references	Walker, G.W. and MacLeod, N.S., 1991, Geologic map of Oregon: U.S. Geological Survey, scale 1:500,000. Walker, G.W., 1977, Geologic map of Oregon east of the 121st meridian: U.S. Geological Survey Miscellaneous Geologic Investigations Map I-902, scale 1:500,000. [http://pubs.er.usgs.gov/publication/i902] Swisher, C.C., Ach, J.A., and Hart, W.K., 1990, Laser fusion 40Ar/39Ar dating of the type Steens Mountain Basalt, southeastern Oregon, and the age of the Steens aeromagnetic polarity transition [abs.]: EOS, Transactions of American Geophysical Union, v. 17, no. 43, p. 1,296. Beeson, J.H., Geology of the southern half of the Huntington quadrangle, Oregon: Eugene, University of Oregon, master's thesis, 77 p.
Geographic coverage	Baker - Crook - Harney - Klamath - Lake - Linn - Malheur - Wasco