Rhyolite and dacite

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
Geologic age Pleistocene to Holocene
Lithologic constituents
Igneous > Volcanic > Felsic-volcanic > Dacite (Dome, Flow)
Igneous > Volcanic > Felsic-volcanic > Rhyolite (Dome, Flow)

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

NGMDB product
Counties Deschutes - Klamath - Lane