Rhyolite and dacite (Holocene and Pleistocene)

Domes and related flows and flow breccia of aphyric and plagioclase and hornblende porphyritic rhyolite and dacite. Includes rhyolite and dacite on Newberry volcano and at South Sister volcano in the Cascade Range that are younger than Mazama ash deposits (Qma , Qmp; radiometrically dated by 14C methods at approximately 6,800 yr old)
State Oregon
Name Rhyolite and dacite (Holocene and Pleistocene)
Geologic age Pleistocene to Holocene
Primary rock type rhyolite
Secondary rock type dacite
Other rock types tuff
Lithologic constituents
Minor
Igneous > Volcanic > Felsic-volcanic > Rhyolite (Dome)
Igneous > Volcanic > Felsic-volcanic > Rhyolite (Flow)
Igneous > Volcanic > Felsic-volcanic > Dacite (Flow)
Igneous > Volcanic > Felsic-volcanic > Dacite (Dome)
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.
Counties Deschutes - Klamath - Lane