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 (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 geologic time scale 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.

Holocene-Pliocene Sediments

Quaternary Basalt

Quaternary-Tertiary VolcanicRocks

Tertiary Sediments

Tertiary Volcanic Rocks

Tertiary Basalts

Tertiary Intrusive Rocks

Cretaceous Intrusive Rocks

Mesozoic Sedimentary Rocks

Permian-Cretaceous Metamorphicand Intrusive Rocks

Paleozoic Sedimentary Rocks

Precambrian Intrusive Rocks

Precambrian Metamorphic andSedimentary Rocks

GEOLOGY OF IDAHO

IdahoBatholith

TheIdahoBatholithisacompositemassofgraniticplutonscoveringapproximately35,000km2.Intrusiveigneousrocks:granitic,granodioriteandtonalite.Threelobesseparatedbygeologyandgeography;KaniksuLobeintheIdahopanhandle,AtlantaandBitterrootlobesincentralIdaho.

110‐75Ma LateCretaceous

BeltSupergroup

MesoproterozoicsedimentaryrocksdepositedinariftbasinlocatedinwhatisnownorthIdahoandwesternMontana.MissoulaGroup,PieganGroup,RavalliGroup,andLowerBelt.

1470‐1400Ma

Mesoproterozoic

NorthernThrustBelt

North‐westtosouth‐easttrendingthrustfaults(lateCretaceous)whichcutthroughMesoproterozoicSedimentaryrocksoftheBeltSupergroup(sandstone,shale,limestone).

1450‐1400Madeposits.

Mesoproterozoic,LateCretaceous

Idaho‐WyomingThrustBelt

TheIdaho‐WyomingthrustbeltisonesegmentoftheCordilleranthrustbeltthatcontainsfoldedandthrustedPaleozoicandMesozoicsedimentaryrocks.ThethrustfaultsfoldedandcompressedearlieremplacedsedimentsinlateMesozoicandearlyTertiary,trendingnorth‐westtosouth‐east.

700‐150Madeposited.150to55Mathrustfaulting.

Neoproterozoic,Paleozoic,Triassic,Jurassic

ChallisVolcanics

Flare‐upofvolcanicactivityincentralIdahocreatingintrusivepinkgraniteanderuptionsofrhyolitelavas.Andesiteanddacitewithextensionalfaulting.Formationofmajormineraldeposits.

52‐45Ma Eocene

AccretedTerranes

WesternedgecentralIdaho.MiddleCretaceous(120‐100Ma)accretionof"exotic"TerranesofPaleozoiclimestoneontopofoceanicvolcanicrockwithJurassicintrusions.SevenDevilsGroup.

~370‐250Ma&150‐170Maintrusions

Paleozoic&Mesozoic

ColumbiaRiverBasalt

ExtensiveplateauofvolcanicbasaltandrhyolitelocatedonthewesternedgeofcentralIdaho.

17Ma MiddleMiocene

BasinandRange

Beginningabout17millionyearsago,linearmountainrangesinsouth‐eastIdaho,consistingofsedimentarysandstone,shaleandlimestone,brokenbyNW‐SEtrendingnormalfaults(extensionalforces).CutbySnakeRiverPlain

700‐150Ma.Neoproterozoic&Paleozoicsediments

SnakeRiverPlain

BeltacrosssouthernIdahoconsistingofIdavadaVolcanics,YellowstoneVolcanics(rhyolite),SnakeRiverBasaltwithsomeQuaternarySedimentaryrocks.Createdbythepassageofthecontinentovera"HotSpot".

17Ma‐Present

MiocenetoHolocene

OwyheePlateau

AregioninsouthwesternIdahorelatedtotheSnakeRiverPlainbutremainedahighlandregionofIdavadaandYellowstonevolcanics,andSnakeRiverBasalt.Felsicvolcanics,Miocenesilicicflowsandtuffs.

17Ma Miocene

Geology Description Age Period

by Diana Boyack boyadian@isu.edu modified July 16, 2007

Pliocene

Miocene

Oligocene

Eocene

Paleocene

Neog

ene

Pale

ogen

eTe

rtiar

y

Cretaceous

Jurassic

Triassic

Mes

ozoi

cPr

ePha

nero

zoic

A r c h e a n

Eon

Era Period Epoch

Holocene

Pleistocene

Qua

tern

ary

Ceno

zoic

Oldest Rock ~3900 MaEarth ~4600 Ma

Mississippian

Devonian

Silurian

Ordovician

Cambrian

Ph

an

er

oz

oic

Permian

Pennsylvanian

Pale

ozoi

c

Neo-(late)

Prec

ambr

ian

Prot

eroz

oic

Meso-(middle)

Paleo-(early)1600 Ma

1000 Ma

540 Ma

505 Ma

438 Ma

408 Ma

360 Ma

320 Ma

286 Ma

245 Ma

208 Ma

144 Ma

66 Ma

58 Ma

37 Ma

24 Ma

5 Ma

2 Ma

10,000 yrs

2500 Ma

Carb

onife

rous

Geologic Time

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.