Geology

Description

Age

Period

Idaho Batholith
The Idaho Batholith is a composite mass of granitic plutons covering approximately 35,000 km2. Intrusive igneous rocks: granitic, granodiorite and tonalite. Three lobes separated by geology and geography; Kaniksu Lobe in the Idaho panhandle, Atlanta and Bitterroot lobes in central Idaho.
110 - 75 Ma
Late Cretaceous
Belt Supergroup
Mesoproterozoic sedimentary rocks deposited in a rift basin located in what is now north Idaho and western Montana. Missoula Group, Piegan Group, Ravalli Group, and Lower Belt.
1470-1400 Ma
Mesoproterozoic
Northern Thrust Belt
North-west to south-east trending thrust faults (late Cretaceous) which cut through Mesoproterozoic Sedimentary rocks of the Belt Supergroup (sandstone, shale, limestone).
1450-1400 Ma deposits.
Mesoproterozoic
Late Cretaceous
Idaho-Wyoming Thrust Belt
The Idaho-Wyoming thrust belt is one segment of the Cordilleran thrust belt that contains folded and thrusted Paleozoic and Mesozoic sedimentary rocks.
The thrust faults folded and compressed earlier emplaced sediments in late Mesozoic and early Tertiary, trending north-west to south-east.
700-150 Ma deposited.
150 to 55 Ma thrust faulting.
Neoproterozoic, Paleozoic, Triassic, Jurassic
Challis Volcanics
Flare-up of volcanic activity in central Idaho creating intrusive pink granite and eruptions of rhyolite lavas. Andesite and dacite with extensional faulting. Formation of major mineral deposits.
52-45 Ma
Eocene
Accreted Terranes
Western edge central Idaho. Middle Cretaceous (120-100 Ma) accretion of "exotic" Terranes of Paleozoic limestone on top of oceanic volcanic rock with Jurassic intrusions. Seven Devils Group.
~370 - 250 Ma and 150 - 170 Ma intrusions
Paleozoic & Mesozoic
Columbia River Basalt
Extensive plateau of volcanic basalt and rhyolite located on the western edge of central Idaho.
17 Ma
Middle Miocene
Basin and Range
Belt across southern Idaho consisting of Idavada Volcanics, Yellowstone Volcanics (rhyolite), Snake River Basalt with some Quaternary Sedimentary rocks. Created by the passage of the continent over a "Hot Spot".
700-150 Ma
Neoproterozoic & Paleozoic sediments
Snake River Plain
Belt across southern Idaho consisting of Idavada Volcanics, Yellowstone Volcanics (rhyolite), Snake River Basalt with some Quaternary Sedimentary rocks. Created by the passage of the continent over a "Hot Spot".
17 Ma-Present
Miocene to Holocene
Owyhee Plateau
A region in southwestern Idaho related to the Snake River Plain but remained a highland region of Idavada and Yellowstone volcanics, and Snake River Basalt. Felsic volcanics, Miocene silicic flows and tuffs.
17 Ma
Miocene