Digital Geology of Idaho Digital Atlas Link Digital Geology Link

Introduction to Idaho Geology Web Course

The "Digital Geology of Idaho" systematically divides Idaho geology into individual teaching modules. The modules correspond with a 15-week Geology of Idaho course (Geol 456-556 for 2 credits). Modules can serve as a source of information, reference, maps and photographs of Idaho geology.

The Digital Atlas of Idaho is written at a more accessible level, and is a resource that also contains exercises for K-12 teachers.

Geology of Idaho

A New Idaho Geologic Map

Another component of this project was preparation of a new Geologic Map of Idaho by the Idaho Geological Survey. The map on the left is a simplified version of this new geologic map. Each of the modules on this web site contain derivative geologic maps showing specific map units. The new Geologic Map of Idaho can be purchased for the Idaho Geological Survey.


Most modules have mulitiple digital watershed fly-through visualizations where geology has been " draped" over topography to provide a graphic visualization of the geology along Idaho river basins.

Bonneville Flood Visualizations

Module 14, "Lake Bonneville Flood", has extensive visualizations created by Dr. Shuhab Khan and his students at the University of Houston.

Slide Shows   slideshow

Slide shows used in the modules include photos by Paul Link, and by Jim Cash of Moscow High School, and Reed Lewis of the Idaho Geological Survey. A pdf reader is needed to view slide shows and many of the images which enlarge to pdf format.

Module 1 -
Idaho Basement Rock
Module 2 -
Belt Supergroup
Module 3 -
Rifting and The Passive Margin
Module 4 -
Accreted Terranes
Module 5 -
Thrust Belt
Module 6 -
Idaho Batholith
Module 7 -
Geology of Northern Idaho and The Silver Valley
Module 8 -
Challis Magmatism
Module 9 -
Basin & Range Province - Tertiary Extension
Module 10 -
Columbia River Basalts
Module 11 -
Snake River Plain ... Yellowstone Provinces
Module 12 -
Pleistocene Glaciation
Module 13 -
Palouse and Lake Missoula Flood
Module 14 -
Lake Bonneville Flood
Module 15 -
Snake River Plain Aquifer
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flythroughIdaho from the Air
flythroughWatershed Fly-Throughs
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Idaho Geography

Geologic Overview of Idaho

Idaho has a complicated geologic history which is reflected in its physical geography. The shaded relief map of Idaho shows the mountain ranges, and the major cities to give an idea of how the state is subdivided by its geography.

slideshow "Idaho from the Air" pdf slideshow is a compilation of aerial photos taken by Paul Link. They give a unique perpective of the Idaho landscape.

The geologic provinces of Idaho are briefly summarized in the table below. A geologic time scale is included to help with the perspective of the great amount of time that geologic history spans.

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Idaho River Drainages

Below are links to animations of the drainages in Idaho, broken down by regions of Idaho. Idaho Rivers

Click here for an animation of Southern Idaho Rivers.

Click here for an animation of Central Idaho Rivers.

Click here for an animation of Northern .

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Idaho Geologic Provinces

Idaho Geologic Provinices Geologic Time Scale





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
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.
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
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
Beginning about 17 million years ago, linear mountain ranges in south-east Idaho, consisting of sedimentary sandstone, shale and limestone, broken by NW-SE trending normal faults (extensional forces). Cut by the Snake River Plain.
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



Continue to  Module 1 - Idaho Basement Rock

Specific research papers and field trip guides are listed under each module.


Resources recommended to accompany the Idaho Geology course are listed below.
Many are included as pdf files throughout the website.

Publications resulting from this NSF grant include: