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Home , Mesoproterozoic

Introduction to Idaho 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 (Geology 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 a resource that also contains exercises for K-12 teachers.

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.

Fly-throughs Most modules have multiple 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.

"Idaho from the Air" pdf slideshow is a compilation of aerial photos taken by Paul Link. They give a unique perspective of the Idaho landscape. The geologic provinces of Idaho are briefly summarized in the table below. A is included to help with the perspective of the great amount of time that geologic history spans.

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. GEOLOGY OF IDAHO

Holocene- Sediments

Quaternary Basalt

Quaternary-Tertiary Volcanic Rocks

Tertiary Sediments

Tertiary Volcanic Rocks

Tertiary Basalts

Tertiary Intrusive Rocks

Cretaceous Intrusive Rocks

Mesozoic Sedimentary Rocks

Permian-Cretaceous Metamorphic and Intrusive Rocks

Paleozoic Sedimentary Rocks

Precambrian Intrusive Rocks

Precambrian Metamorphic and Sedimentary Rocks

Geology Description Age Period

The Idaho Batholith is a composite mass of granitic plutons covering approximately 35,000 km2. Intrusive igneous rocks: Idaho Batholith granitic, granodiorite and tonalite. Three lobes separated by 110 ‐ 75 Ma geology and geography; Kaniksu Lobe in the Idaho panhandle, Atlanta and Bitterroot lobes in central Idaho.

Mesoproterozoic sedimentary rocks deposited in a rift basin Belt 1470‐1400 located in what is now north Idaho and western Montana. Mesoproterozoic Supergroup Ma Missoula Group, Piegan Group, Ravalli Group, and Lower Belt.

North‐west to south‐east trending thrust faults (late Cretaceous) Northern 1450‐1400 Mesoproterozoic, which cut through Mesoproterozoic Sedimentary rocks of the Belt Thrust Belt Ma deposits. Late Cretaceous Supergroup (sandstone, shale, limestone).

The Idaho‐Wyoming thrust belt is one segment of the Cordilleran 700‐150 Ma Idaho‐ thrust belt that contains folded and thrusted Paleozoic and deposited. , Wyoming sedimentary rocks. The thrust faults folded and 150 to 55 Ma Paleozoic, Triassic, Thrust Belt compressed earlier emplaced sediments in late Mesozoic and thrust Jurassic early Tertiary, trending north‐west to south‐east. faulting.

Flare‐up of volcanic activity in central Idaho creating intrusive Challis pink granite and eruptions of rhyolite lavas. Andesite and dacite 52‐45 Ma Volcanics with extensional faulting. Formation of major mineral deposits.

Western edge central Idaho. Middle Cretaceous (120‐100 Ma) ~370 ‐ 250 Accreted accretion of "exotic" Terranes of Paleozoic limestone on top of Ma & 150 ‐ Paleozoic & Terranes oceanic volcanic rock with Jurassic intrusions. Seven Devils 170 Ma Mesozoic Group. intrusions

Columbia River Extensive plateau of volcanic basalt and rhyolite located on the 17 Ma Middle Basalt western edge of central Idaho.

Beginning about 17 million ago, linear mountain ranges in Neoproterozoic & Basin and south‐east Idaho, consisting of sedimentary sandstone, shale and 700 ‐ 150 Ma. Paleozoic Range limestone, broken by NW‐SE trending normal faults (extensional sediments forces). Cut by Snake River Plain

Belt across southern Idaho consisting of Idavada Volcanics, Snake River Yellowstone Volcanics (rhyolite), Snake River Basalt with some 17 Ma‐ Miocene to Plain Quaternary Sedimentary rocks. Created by the passage of the Present continent over a "Hot Spot".

A region in southwestern Idaho related to the Snake River Plain Owyhee but remained a highland region of Idavada and Yellowstone 17 Ma Miocene Plateau volcanics, and Snake River Basalt. Felsic volcanics, Miocene silicic flows and tuffs. Geologic Time Period Epoch Eon Holocene 10,000 yrs

Pleistocene

Quaternary 2 Ma Pliocene 5 Ma

Miocene Neogene 24 Ma Cenozoic 37 Ma Tertiary Eocene 58 Ma

Paleogene 66 Ma Cretaceous 144 Ma Jurassic 208 Ma Mesozoic Triassic 245 Ma Permian 286 Ma

Phanerozoic 320 Ma

Carboniferous 360 Ma Devonian 408 Ma

Paleozoic Silurian 438 Ma Ordovician 505 Ma Cambrian 540 Ma

Neo- (late)

1000 Ma

Meso- (middle) Precambrian PrePhanerozoic

1600 Ma Paleo-(early) 2500 Ma

Oldest Rock ~3900 Ma Earth ~4600 Ma

by Diana Boyack [email protected] modified July 16, 2007 Specific research papers and field trip guides are listed with each module. Some resources recommended to accompany the Idaho Geology course are listed below. Many are included as pdf files throughout the website.

 ALT, D. AND HYNDMAN, D., 1989, ROADSIDE GEOLOGY OF IDAHO, MOUNTAIN PRESS, MISSOULA, MT.  DIGITAL ATLAS OF IDAHO: HTTP://IMNH.ISU.EDU/DIGITALATLAS  LINK, P. K. AND PHOENIX, E. C., 1996, 2ND EDITION, "ROCKS, RAILS, AND TRAILS" , IDAHO MUSEUM OF NATURAL HISTORY. (AVAILABLE DIGITALLY ON THE DIGITAL ATLAS OF IDAHO WEBSITE)  ORR, W. N. AND ORR, E. L., 2002, (2006 REISSUE), GEOLOGY OF THE PACIFIC NORTHWEST , WAVELAND PRESS, LONG GROVE, IL, 337 P.  VALLIER, T., 1998, ISLANDS AND RAPIDS: A GEOLOGIC STORY OF HELLS CANYON, CONFLUENCE PRESS, LEWISTON, ID 151P. Publications resulting from this NSF grant include:  JAMES R. CASH, J.R., LEWIS, R.S., AND STURGIS, D.J., PHOTOGRAPHS OF THE GEOLOGY OF CENTRAL AND NORTHERN IDAHO : IDAHO GEOLOGICAL SURVEY INFORMATION CIRCULAR I-62 HTTP://WWW.IDAHOGEOLOGY.ORG/  LINK, P.K., LEWIS, R.S., AND STANFORD, L., 2008 , GEOLOGIC MAP OF IDAHO, IDAHO GEOLOGICAL SURVEY, SCALE 1:500,000.  LONG, SEAN P. AND LINK, PAUL K., 2007, GEOLOGIC MAP COMPILATION OF THE MALAD CITY 30 X 60 MINUTE QUADRANGLE, IDAHO, IDAHO GEOLOGICAL SURVEY MAP: T-07-1, SCALE 1:100,000.  RODGERS, D.W., ET AL., 2006. GEOLOGIC MAP OF THE INKOM QUADRANGLE, BANNOCK COUNTY, IDAHO, IDAHO GEOLOGICAL SURVEY MAP: T-06-2, SCALE: 1:24,000. Acknowledgements THIS WEB SITE WAS DEVELOPED BY PAUL K. LINK OF IDAHO STATE UNIVERSITY, REED S. LEWIS OF THE IDAHO GEOLOGICAL SURVEY, SHUHAB KHAN OF THE UNIVERSITY OF HOUSTON, AND KEEGAN SCHMIDT OF LEWIS-CLARK STATE COLLEGE, THESE WERE PREPARED BY STUDENTS OF DR. DAN AMES, IDAHO STATE UNIVERSITY, IDAHO FALLS, WITH FUNDING FROM THE NATIONAL SCIENCE FOUNDATION GEOSCIENCE EDUCATION PROGRAM - NSF GEO-0331174. CONTRIBUTORS TO CONTENT AND DESIGN ARE: LAURA DEGREY, LORI TAPANILA, NATE ARAVE, KRISTEN STRAUB, AND DIANA BOYACK AND MANY STUDENTS IN VARIOUS CLASSES AT IDAHO STATE UNIVERSITY.