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The Quick Story

The Quick Story. 1 Billion Years of PNW Geology in 10 (text) Slides or Less. Important Processes. Tectonics Volcanism Erosion/Deposition Glaciation Discrete Disturbances. PNW Timeline A. 4.5 BYA Earth Formed ~ 4.4 – 4. 2 BY Oldest Rocks (U in Zircon degradation to lead Pb)

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The Quick Story

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  1. The Quick Story 1 Billion Years of PNW Geology in 10 (text) Slides or Less

  2. Important Processes • Tectonics • Volcanism • Erosion/Deposition • Glaciation • Discrete Disturbances

  3. PNW Timeline A • 4.5 BYA Earth Formed • ~ 4.4 – 4. 2 BY Oldest Rocks (U in Zircon degradation to lead Pb) • 2.7 BYA basement Rocks in MT, ID • 1.5 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

  4. Geologic Time Scale

  5. 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 mya Holocene Epoch ~15,000 to present Pleistocene Epoch 1.8 mya Pliocene Epoch 5.3 mya Miocene Epoch 23 mya Paleogene Period Oligocene Epoch 33 mya Eocene Epoch 55 mya Paleocene Epoch 65 mya Cenozoic Era (New Life)

  6. 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 mya Holocene Epoch ~15,000 to present Pleistocene Epoch 1.8 mya Pliocene Epoch 5.3 mya Miocene Epoch 23 mya Paleogene Period Oligocene Epoch 33 mya Eocene Epoch 55 mya Paleocene Epoch 65 mya Cenozoic Era (New Life)

  7. 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

  8. From Orr and Orr, 2005, p. 6

  9. From Orr and Orr, 2005, p. 2

  10. From Orr and Orr, 2005, p. 5

  11. PNW Timeline C • ~ 144 mya – 65 mya Cretaceous Epoch of Mesozoic Era • Batholith intrusions throughout PNW • N. Cascade Terrane Collides (started 500 mya) • Insular and Blue Mt. Terranes Collide • Idaho Batholith late Cretaceous • Large 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

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

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

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

  15. 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 subducted • Blue Mts. Rotate/arch upward • John Day Volcanism smothers fossils • Wet, Warm Tropical Environment changes to dry temperate • ~20 – 5 mya Coast Range (not BC) and Olympics uplift

  16. Cenozoic Era (New Life) • Two periods of New Version: • Neogene Period 23 mya • Holocene Epoch ~15,000 to present • Pleistocene Epoch 1.8 mya • Pliocene Epoch 5.3 mya • Miocene Epoch 23 mya • Paleogene Period • Oligocene Epoch 33 mya • Eocene Epoch 55 mya • Paleocene Epoch 65 mya

  17. From Alt and Hyndman, 1995, p. 171

  18. 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 eruptions • Cascade Rainshadow “renewed” • Dry, cooler inland Climate  Continental Climate • Temperate Climate to west  Maritime Climate

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

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

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

  22. Timeline F • ~2 – 3 mya Puget Lowlands and Willamette valley forming – rift faulting? • Long dry spell • Yellowstone (2.2 mya and 640,000 ya) eruption • THEN Pleistocene 1.8 mya • 100,000 years ago first glaciation • Long series of glacial phases (colder – wetter/warmer – drier) • Lake Missoula (+/- 100s?)and Bonneville (1) floods • 10,000 years ago ice age ends • E. Snake River basalts • Mazama (5,677 (± 150) ya) eruption

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

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

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

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

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

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

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

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

  31. Puget Sound • At Glacial Maxima Seattle under up to 1000m of ice • Lakes 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 Mounds • Clays and Till • Morraines

  32. From Orr and Orr, 2005, p. 17

  33. From Orr and Orr, 2005, p. 17

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

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

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

  37. Sources • Orr, 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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