1 Billion Years of PNW Geology in 10 (text) Slides or Less

1 Billion Years of PNW Geology in 10 (text) Slides or Less

Important ProcessesTectonicsVolcanismErosion/DepositionGlaciationDiscrete Disturbances

PNW Timeline A4.5 BYA Earth Formed~ 4.4 – 4. 2 BY Oldest Rocks (U in Zircon

degradation to lead Pb)2.7 BYA basement Rocks in MT, ID1.5 BYA Purcell Belt Basin~44o MYA Pangaea Starts to Assemble (Silurian

Epoch of Paleozoic Era)Coastline ~ Idaho border. 30,000 feet of marine

sediment accumulates~ 400 mya Blue Mt. Terrane forming in tropical Pacific

(limestone)(made of 5+ terranes)Klamath Arc Collides, Antler Highlands (proto-Sierras)Intermontane, insular terranes develop in S.W. Pacific

Metamorphosed to Become

Geologic Time Scale

Eon Era PeriodAge at Base*

(start)

Phanerozoic

CenozoicQuaternary 1.6 Ma

Tertiary 65 Ma

Mesozoic

Cretaceous 140 Ma

Jurassic 205 Ma

Triassic 250 Ma

Paleozoic

Permian 290 Ma

Carboniferous

355 Ma

Devonian 410 Ma

Silurian 438 Ma

Ordovician 510 Ma

Cambrian 540 Ma

Precambrian

Proterozoic

Vendian 680 Ma

2500 Ma

Archean 3960 Ma

Hadean 4550 Ma

Cenozoic Era (New Life)Two periods of Old

Version:Quaternary Period 1.6

mya Holocene Pleistocene

Tertiary Period 65 mya Pliocene Paleocene or Miocene

Two periods of New Version:

Neogene Period 23 myaHolocene Epoch ~15,000

to presentPleistocene Epoch 1.8

myaPliocene Epoch 5.3 mya Miocene Epoch 23 mya

Paleogene PeriodOligocene Epoch 33 myaEocene Epoch 55 myaPaleocene Epoch 65 mya

Cenozoic Era (New Life)Two periods of Old

Version:Quaternary Period 1.6

mya Holocene Pleistocene

Tertiary Period 65 mya Pliocene Paleocene or Miocene

Two periods of New Version:

Neogene Period 23 myaHolocene Epoch ~15,000

to presentPleistocene Epoch 1.8

myaPliocene Epoch 5.3 mya Miocene Epoch 23 mya


PNW Timeline B~245 MYA Pangaea Assembled (Permian Epoch of Paleozoic

Era) Large, warm seas Several (lost) sub/mini continents/islands in Pacific

Permian – Triassic Extinction Event ~251 mya Larger extinction event than K-T Impacts, Volcanism, Methane Hydrates from sea floor (?)

~200 MYA Pangaea Starts to Break up (Triassic Epoch of Mesozoic Era) Forms Laurasia (N) and Gondwanaland (S) Marine Seas changing to smaller back arc basins with volcanic

chains~ 140 mya Laurasia Breaks Up (Jurassic Epoch of Mesozoic Era)

Ocean rift starts to form Atlantic Ocean N. America moves across Pacific and Farallon Plates

(subduction) Intermontane Superterrane Collides with N. America

From Orr and Orr, 2005, p. 6



PNW Timeline C~ 144 mya – 65 mya Cretaceous Epoch of

Mesozoic EraBatholith intrusions throughout PNWN. Cascade Terrane Collides (started 500 mya)Insular and Blue Mt. Terranes CollideIdaho Batholith late CretaceousLarge Seas cover PNW

BAM! Huge Meteor hits Earth, Extinction of Dinosaurs (K-T Extinction Event)Location: Yucatan Peninsula (others? SL-9)Deccan Traps alternative Hypothesis?

Farallon Plate subducts with less angle, faster

Several km in Diameter; ~ hundreds of nuclear weaponshttp://en.wikipedia.org/wiki/Image:Impact_event.jpg

http://en.wikipedia.org/wiki/Image:Chicxulub_radar_topography.jpg

http://upload.wikimedia.org/wikipedia/commons/5/57/K-T_boundary.jpg

Timeline D~58 mya Coast Range Mt. Volcanism (ocean)Pacific Rim, Crescent, Siletz Terranes “arrive”Farallon Plate subducts steeper, slower~40 mya W. Cascade Volcanism Begins (old

Cascades)~ 36 mya Kula Plate completely subductedBlue Mts. Rotate/arch upwardJohn Day Volcanism smothers fossilsWet, Warm Tropical Environment changes to dry

temperate~20 – 5 mya Coast Range (not BC) and Olympics

uplift

Cenozoic Era (New Life)Two periods of New Version:Neogene Period 23 mya

Holocene Epoch ~15,000 to presentPleistocene Epoch 1.8 myaPliocene Epoch 5.3 mya Miocene Epoch 23 mya


From Alt and Hyndman, 1995, p. 171

Timeline E~17 -- 14 mya Flood Basalts in WA and OR

(Steens Basalt)17 – 15 mya Basin and Range (fault-blocks from

spreading)~13 mya Snake River Plain Hotspot (at

Yellowstone now)~5.3 mya First High Cascades eruptionsCascade Rainshadow “renewed”

Dry, cooler inland Climate Continental ClimateTemperate Climate to west Maritime Climate

http://en.wikipedia.org/wiki/Image:3-Devils-grade-Moses-Coulee-Cattle-Feed-Lot-PB110016.JPG

http://en.wikipedia.org/wiki/Image:Horst_graben.jpg

http://en.wikipedia.org/wiki/Image:HotspotsSRP.jpg

Timeline F~2 – 3 mya Puget Lowlands and Willamette valley

forming – rift faulting?Long dry spellYellowstone (2.2 mya and 640,000 ya) eruptionTHEN Pleistocene 1.8 mya

100,000 years ago first glaciationLong series of glacial phases (colder –

wetter/warmer – drier)Lake Missoula (+/- 100s?)and Bonneville (1) floods10,000 years ago ice age endsE. Snake River basaltsMazama (5,677 (± 150) ya) eruption

http://en.wikipedia.org/wiki/Image:Northern_icesheet_hg.png

http://www.nwcreation.net/articles/missoulaflood.htm

http://www.greaterthings.com/News/daily/2005/09/06/6600916_Bush_behind_Katrina/Lake-Bonneville-and-Utah.jpg

http://pubs.usgs.gov/fs/2002/fs092-02/

http://volcano.und.edu/vwdocs/volc_images/north_america/crater_lake.html

http://en.wikipedia.org/wiki/Image:HotspotsSRP.jpg

http://www.exodus2006.com/supervol.html

http://en.wikipedia.org/wiki/Image:Yellowstone_Caldera_map2.jpg

Puget Sound At Glacial Maxima Seattle under up to 1000m of

iceLakes formed at edges of glaciers (Russell,

Nisqually, Bretz, many others)Some drained into Chehalis River (underutilized

drainage)Water changed from fresh to brine/salt

(extinction)As Glaciers receded, glacial formations

Mima MoundsClays and TillMorraines



http://en.wikipedia.org/wiki/Image:Puget_Sound_from_Space_Needle_High_Rex.jpg

http://en.wikipedia.org/wiki/Image:Cascade_Range-related_plate_tectonics.svg

http://en.wikipedia.org/wiki/Image:Cascade_eruptions_in_the_last_4000_years.png

SourcesOrr, W.N. and E.L. Orr. 2006. Geology of the Pacific

Northwest. Waveland Press, Long Grove, IL.Alt, D. and D.W. Hyndman. 1995. Northwest Exposures.

Mountain Press Publishing Company, Missoula, MT. Check out this website to reconstruct plate tectonic movements

on your own: http://www.odsn.de/odsn/services/paleomap/paleomap.html

Check out KT Event: http://en.wikipedia.org/wiki/Cretaceous_extinction

Also look at QuickTime movie of Puget Sound Glaciation at http://exhibits.pacsci.org/puget_sound/graphics/ps_glaciationsm.mov

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1 Billion Years of PNW Geology in 10 (text) Slides or Less