Subaqueous pyroclastic ejecta of basaltic cinder cones (lower Pliocene? and Miocene?)

Deposits of bombs, breccia, and mafic to intermediate tuff; occurs as palagonitic tuff and breccia cones, rings, and ridges. In places interbedded with lacustrine sedimentary rocks
State Oregon
Name Subaqueous pyroclastic ejecta of basaltic cinder cones (lower Pliocene? and Miocene?)
Geologic age Miocene to Early Pliocene
Primary rock type pyroclastic
Secondary rock type mafic volcanic rock
Other rock types intermediate volcanic rock
Lithologic constituents
Major
Igneous > Volcanic > Mafic-volcanic > Basalt (Pyroclastic, cinder cone)Also contains material of intermediate composition (basaltic andesite and (or) andesite
Incidental
Sedimentary > Clastic > Mixed-clastic > Sandstone-Mudstone (Bed)
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.
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.
Ferns, M.L. and Cummings, M.L., 1992, Geology and mineral resources map of The Elbow quadrangle, Malheur County, Oregon: Oregon Department of Geology and Mineral Industries Geological Map Series GMS-62, scale 1:24,000.
Ferns, M.L., 1992, Preliminary geologic map of the Jordan Craters South quadrangle, Malheur County, Oregon: Oregon Department of Geology and Mineral Industries Open-File Map O-92-09, scale 1:24,000.
Beeson, J.H., Geology of the southern half of the Huntington quadrangle, Oregon: Eugene, University of Oregon, master's thesis, 77 p.
Counties Baker - Crook - Harney - Klamath - Lake - Linn - Malheur