Camas County contains the Soldier Mountains, Camas Prairie and Mout Bennett Hills on the northern edge of the Snake River Plain, west of the Wood River.
The Camas Prairie is a flat, alluvial covered agricultural area, downdropped from the Soldier Mountains by a concealed normal fault. The Mount Bennett Hills contain Miocene (12 to 8 Ma) rhyolites from the Twin Falls volcanic centers. The latest Miocene Magic Reservoir rhyolite dome and eruptive complex is found in the southeast corner of the county.
The Soldier Mountains, and the Smoky Mountains to the northeast are underlain by Cretaceous granodiorite from the Idaho batholith, as well as complex Eocene intrusive complexes associated with the Challis magmatic episode. Diverse metallic mineral deposits occur here, associated with carbonaceous Paleozoic rocks of the central Idaho black-shale mineral belt, and Cretaceous and Eocene hydrothermal mineralizing systems.
See sections on geology of this area in Rocks, Rails and Trails.
P.K. Link, 10/02
Rocks Rails and Trails:
The Snake River Plain-Yellowstone Hot Spot and its Effect on Drainage Patterns
Drainage Systems, Rails and Trails
Geologic Provinces along the Oregon Trail
Rocks of the Eastern Idaho Mountains
Rocks of Central Idaho
Pictures -Idaho Mountains
Challis Volcanic Group & Intrusive Rocks
References on Idaho Geology
Section 8, Chapter 24 -Ketchum, Sun Valley, and Shoshone
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