Rhyolites

In Northwestern Utah: Dacitic tuff (8.5 my). In Logan-Huntsville Allochthon: rhyolite.
State Utah
Name Rhyolites
Geologic age Middle to Late Miocene
Lithologic constituents
Major
Igneous > Volcanic > Felsic-volcanic > Rhyolite (Flow)
Minor
Igneous > Volcanic > Felsic-volcanic > Dacite (Pyroclastic-tuff, Flow)
Stratigraphic units Etna, Hogback, Topaz Mountain, Keg Mountains, Gillies Hill, Steamboat Mountain
References

Hintze, L.F., 1980, Geologic map of Utah: Utah Geological and Mineral Survey, scale 1:500,000.

Hintze, L.F., 1988, Geologic History of Utah: Brigham Young University Geology Studies Special Publication 7, 202 p.

NGMDB product
Counties Beaver - Box Elder - Garfield - Iron - Juab - Millard - Piute - Salt Lake - Sevier - Tooele