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Continental sedimentary rocks (upper and middle Miocene)

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Poorly sorted and poorly bedded, fine- to coarse-grained tuffaceous siltstone, sandstone, pebble conglomerate, agglomerate, volcanic cobble conglomerate, air-fall tuff, and rare basaltic andesite flows equivalent to those in unit Tba. Included in the Miocene Sardine Formation by Peck and others (1964)
State Oregon
Name Continental sedimentary rocks (upper and middle Miocene)
Geologic age Middle Miocene to Late Miocene
Primary rock type siltstone
Secondary rock type sandstone
Other rock types conglomerate; tuff; mafic volcanic rock
Lithologic constituents
Major
Sedimentary > Clastic > Siltstone (Bed)
Sedimentary > Clastic > Sandstone (Bed)
Minor
Sedimentary > Clastic > Conglomerate (Bed)
Incidental
Igneous > Volcanic (Pyroclastic, air fall)
Igneous > Volcanic > Mafic-volcanic > Basaltic-andesite (Flow)
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.
Peck, D.L., Griggs, A.B., Schlicker, H.G., Well, F.G., and Dole, H.M., 1964, Geology of the central and northern parts of the Western Cascade Range in Oregon: U.S. Geolotgical Survey Professional Paper 449, 56 p.
Vokes, H.E., Snavely, P.D., Jr., and Myers, D.A., 1951, Geology of the southern and southwestern border areas of the Willamette valley, Oregon: U.S. Geological Survey Oil and Gas Investigations Map OM-110, scale 1:62,500.
McDougall, K., 1980, Paleoecological evaluation of late Eocene biostratigraphic zonations of the Pacific Coast of North America: Society of economic Paleontologists and Mineralogists, Paleontological Monograph, no. 2, 46 p.
Lux, D.R., 1982, K-Ar and 40Ar/39Ar ages of mid-Tertiary volcanic rocks from the Western Cascade Range, Oregon: Isochron/West, no. 33, p. 27-32.
Counties Clackamas - Linn - Marion