Challis Volcanic Group.

Dacite, andesite, and rhyolite tuffs and flows and subordinate basalt and latite flows; covers large area in south-central Idaho. Includes Absaroka Volcanic Group near Henrys Lake and scattered volcanic rocks in eastern and northern Idaho. (Eocene Challis Magmatic Complex and Related Sedimentary Rocks).
State Idaho
Name Challis Volcanic Group.
Geologic age Eocene
Lithologic constituents
Major
Igneous > Volcanic > Felsic-volcanic > Dacite (Pyroclastic-tuff, Flow)
Igneous > Volcanic > Mafic-volcanic > Andesite (Pyroclastic-tuff, Flow)
Igneous > Volcanic > Felsic-volcanic > Rhyolite (Pyroclastic-tuff, Flow)
Minor
Igneous > Volcanic > Felsic-volcanic > Latite (Flow)
Igneous > Volcanic > Mafic-volcanic > Basalt (Flow)
References

Lewis, Reed S., Link, Paul K., Stanford, Loudon R., and Long, Sean P., Geologic Map of Idaho, 2012, Idaho Geological Survey, Geologic Map 9 (M-9); Scale 1:500,000.

NGMDB product
Counties Bingham - Blaine - Bonneville - Butte - Camas - Clark - Clearwater - Custer - Fremont - Gooding - Idaho - Latah - Lemhi - Owyhee - Valley