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February 5, 2017 Weekly Geology Guess: Columbia River Flood Basalts

February 4, 2017
Greetings from the Bluff Park Back Porch, way up yonder on Shades Mountain (1,109′) in Alabama:

Another twist in the road as I was traveling to the land of Plate Tectonics.  I was rowing my geology boat up the Columbia River and up the Snake River.  I stopped at the Yellowstone Caldera and was fixing to travel overland to the land of Plate Tectonics, of which, Yellowstone NP is part of the process.  I was about to head East when my sister, Schorl, said stop, you can’t leave until you finish up with the Columbia River Flood Basalts.

>    There is a lot of material with this subject.

 

The Columbia River Basalt Group

https://en.wikipedia.org/wiki/Columbia_River_Basalt_Group

 

The Columbia River Basalt Group (including the Steen and Picture Gorge basalts) extends over portions of five states.

Introduction:

“During the middle to late Miocene epoch, the Columbia River flood basalts engulfed about 163,700 km2 (63,200 sq mi) of the Pacific Northwest, forming a large igneous province with an estimated volume of 174,300 km3 (41,800 cu mi). Eruptions were most vigorous from 17–14 million years ago, when over 99 percent of the basalt was released. Less extensive eruptions continued from 14–6 million years ago.[1]

Erosion resulting from the Missoula Floods has extensively exposed these lava flows, laying bare many layers of the basalt flows at Wallula Gap, the lower Palouse River, the Columbia River Gorge and throughout the Channeled Scablands.”  Wikipedia

Formation of the Columbia River Basalt Group

Some time during a 10–15 million-year period, lava flow after lava flow poured out, eventually reaching a thickness of more than 1.8 km (5,900 ft). As the molten rock came to the surface, the Earth’s crust gradually sank into the space left by the rising lava. This subsidence of the crust produced a large, slightly depressed lava plain now known as the Columbia Basin or Columbia River Plateau. The northwesterly advancing lava forced the ancient Columbia River into its present course. The lava, as it flowed over the area, first filled the stream valleys, forming dams that in turn caused impoundments or lakes. In these ancient lake beds are found fossil leaf impressions, petrified wood, fossil insects, and bones of vertebrate animals.[4]  Wikepedia

Cause of the volcanism

Major hot-spots have often been tracked back to flood-basalt events. In this case the Yellowstone hotspot’s initial flood-basalt event occurred near Steens Mountain when the Imnaha and Steens eruptions began. As the North American Plate moved several centimeters per year westward, the eruptions progressed through the Snake River Plain across Idaho and into Wyoming. Consistent with the hot spot hypothesis, the lava flows are progressively younger as one proceeds east along this path.[8]
File:CRB-Yellowstone mantle plume model.jpg
Location of Yellowstone Hotspot in millions of Years Ago
Yellowstone Hot Spot. SnakeRiverMap. NPS, 2013. Kevin Case talk.
The attached pictures of  are for your enjoyment.
>    As with most of my weekly fores into geology, with each topic I could write many papers and dissertations.
>    As usual, I scramble to just stay ahead of my audience.
Note:  I have intentionally reduced the amount of linked graphics in this email due to the amount of space required and trying to untangle everything the following week has been a mess.
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References include:

 

–    Wikipedia
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Editors Note:  It is the intent of this site to keep this discussion as simple as possible, so as to educate the interested general public and not to discuss with the geology crowd the latest geologic theories and nuances.  Thanks, R
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“No copyright infringement intended.

The rights belong to their respective owners”
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Copyright Disclaimer: Under Section 107 of the Copyright Act 1976, allowance is made for “fair use” for purposes such as criticism, comment, news reporting, teaching, scholarship, and research. Fair use is a use permitted by copyright statute that might otherwise be infringing. Non-profit, educational or personal use tips the balance in favor of fair use.
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Author’s Request:  If you see any pictures that you know the source and photographer, let me know immediately.  Thanks!  R

Images have been searched by TinEye Reverse Image Search.  http://tineye.com/

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Next week I hopefully will escape to plate tectonics (the old continental drift).  Another simple topic of which hundreds of PhD dissertations and research articles have written.  A new field less than 2 generations old.

 
 
Enjoy the adventure!
 
Thanks,
R
dikes_above_basalt_as_bridge_over_grande_ronde-saddle-mt-basalt-2011-skal-williamborg

dikes_above_basalt_as_bridge_over_grande_ronde-saddle-mt-basalt-2011-skal-williamborg

grande_ronde_river_and_grande_ronde_basalt-2011-skal-williamborg-talk

grande_ronde_river_and_grande_ronde_basalt-2011-skal-williamborg-talk

hole_in_the_ground_coulee-2011-williamborg

hole_in_the_ground_coulee-2011-williamborg

imnaha_oregon-imnaha-basalt-2006-scott-mainwaring

imnaha_oregon-imnaha-basalt-2006-scott-mainwaring

palouse-canyon-washington-state-2006-williamsborg

palouse-canyon-washington-state-2006-williamsborg

steensmountain_-_view_from_top-2005-tjk-from-flickr

steensmountain_-_view_from_top-2005-tjk-from-flickr

wallula-gap-looking-west-2006-williamborg

wallula-gap-looking-west-2006-williamborg

wallula-gap-the-sisters-2006-williamborg

wallula-gap-the-sisters-2006-williamborg

yaquinahead-light-house-ginkgo-flood-basalt-2005-esyrt-dorhimf

yaquinahead-light-house-ginkgo-flood-basalt-2005-esyrt-dorhimf

corps-engineers-archives_celilo_falls_color-1957-usacoe

corps-engineers-archives_celilo_falls_color-1957-usacoe

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