Eastern Snake River Plain

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Eastern Snake River Plain
2
http//imnh.isu.edu/DIGITALATLAS/geo/snkrvpln/srpt
ext/ssrpmain.htm?102,235?95,227?203,69, March 11,
2009
3
Hot Spot
http//www.stchas.edu/faculty/ewilson/Photos/Plate
s/Hot20Spot20Diagram20001.jpg, March 11, 2009
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Hot Spot

• A hot spot is a concentration of magma below the
  lithospheric plates.
• It remains in one place while the plates move
  above it.
• The plate acts as a conveyor belt as it moves
  over the hot spot while magma from the hot spot
  rises, creating a series of volcanoes.
• This is the process that formed the Hawaiian
  Islands.
• This is also the process that formed a series of
  volcanoes found in Southeast Idaho. The hot spot
  that exists in this region is the Yellowstone Hot
  Spot.

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The Snake River Plain and the Yellowstone Hot Spot

• In the past the North American plate traveled
  over the hot spot.
• The hot spot produced several volcanoes and
  volcanic rift zones (breaks in the volcanoes
  through which lava flows).
• The land was uplifted by the hot spot and then
  sank back down after it passed over the hot spot.
• Water created streams and rivers flowing to away
  from the volcanoes and eventually toward the
  Pacific Ocean.
• The hot spot is now located beneath Yellowstone
  Park.
• The landscape of the Snake River Plain is subject
  to weathering and erosion, so the places that
  were once volcanoes continue to get smaller.

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Yellowstone Hot Spot
http//imnh.isu.edu/digitalatlas/geo/topo/main.htm
?191,64, March 12, 2009
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Hazards

• While there is no longer volcanic activity like
  the activity in the past, the volcanic rift zones
  are a source of minor and potentially major
  earthquakes.
• In preparing for the possibility of earthquakes,
  residents of the Snake River Plain region should
  be aware of the potential for
• Damage to buildings, bridges and roads
• Dams to break
• Gas leaks and explosions
• Power lines destruction causing fires and
  electrical hazards
• Damage to water and sewer systems and other
  infrastructure

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Rock Types of the Snake River Plain
http//geology.isu.edu/Digital_Geology_Idaho/Modul
e11/SRP_YV.jpg, March 11, 2009
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Igneous Rock

• As the North American plate moved over the
  Yellowstone Hot Spot, lava flows from volcanic
  eruptions and volcanic rift zones poured over
  Southeast Idaho.
• Volcanic activity was primarily (1) small, low
  shields, (2) fissure flows, and (3) or large
  tube-fed flows.
• When the lava cooled it formed igneous rocks.

http//vulcan.wr.usgs.gov/Volcanoes/Idaho/descript
ion_idaho_volcanics.html, March 11, 2009
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Igneous Rocks Basalt and Rhyolite
Basalt
Rhyolite
http//imnh.isu.edu/digitalatlas/geo/topo/images/r
hyolite.jpg, March 11, 2009
http//www.ldeo.columbia.edu/czhongqi/Photos/rhyo
lite.JPG, March 11, 2009
http//www.flickr.com/photos/moorruth/536575292/,
March 11, 2009
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Rhyolite and Basalt
Rhyolite, a light colored, fine grained igneous
rock is found at this location. It is thought
the minerals in this rock came from the
continental crust that was melted by magma in the
hot spot. When the lava cooled quickly after
volcanic eruption, the minerals crystalized into
a fine grained rock. Basalt, a dark colored,
fine grained igneous rock is also found at this
location. Basalt is typically associated with
the ocean floor because it is produced at
underwater hot spot volcanoes, volcanic islands
produced in oceanic-oceanic convergent
boundaries, and divergent mid-ocean ridges. The
basalt found in the Snake River Plain region is a
result of hot spot eruptions originating from the
upper mantle. When the dark mineral containing
lava cools above the earths surface, it forms
this fine grained dark igneous rock.
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Rock Types of the Snake River Plain
http//geology.isu.edu/Digital_Geology_Idaho/Modul
e11/SRP_YV.jpg, March 11, 2009
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Rock Types of the East Snake River
PlainSedimentary
http//www.flickr.com/photos/piedmont_fossil/12329
98240/, March 11, 2008
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Sedimentary

• Before the volcanic activity of this region
  began, processes of weathering, erosion,
  compaction, and cementation formed a variety of
  clastic sedimentary rocks.
• Many of these rocks can still be found around the
  boundaries of the river plain.

http//geology.isu.edu/Digital_Geology_Idaho/Modul
e11/SRP_YV.jpg, March 11, 2009
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Sources

• http//imnh.isu.edu/DIGITALATLAS/geo/snkrvpln/srpt
  ext/ssrpmain.htm?102,235?95,227?203,69, March 11,
  2009
• http//geology.isu.edu/Digital_Geology_Idaho/Modul
  e11/SRP_YV.jpg, March 11, 2009
• http//www.flickr.com/photos/piedmont_fossil/12329
  98240/, March 11, 2008
• http//geology.isu.edu/Digital_Geology_Idaho/Modul
  e11/SRP_YV.jpg, March 11, 2009
• http//www.stchas.edu/faculty/ewilson/Photos/Plate
  s/Hot20Spot20Diagram20001.jpg, March 11, 2009
• http//vulcan.wr.usgs.gov/Volcanoes/Idaho/descript
  ion_idaho_volcanics.html, March 11, 2009
• http//www.ldeo.columbia.edu/czhongqi/Photos/rhyo
  lite.JPG, March 11, 2009
• http//www.flickr.com/photos/moorruth/536575292/,
  March 11, 2009
• http//imnh.isu.edu/digitalatlas/geo/topo/images/r
  hyolite.jpg, March 11, 2009
• http//www.stchas.edu/faculty/ewilson/Photos/Plate
  s/Hot20Spot20Diagram20001.jpg, March 11, 2009
• http//imnh.isu.edu/digitalatlas/geo/topo/main.htm
  ?191,64, March 12, 2009