THE CASCADES

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THE CASCADES
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Cascade Mountains Pop Quiz
Mt. Jefferson
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Mt. Bachelor
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Three-fingered Jack
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Mt. Hood
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Lava Butte
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Where are the Cascades?

• http//vulcan.wr.usgs.gov/Volcanoes/Cascades/Image
  Maps/CascadeRange/cascade_range.html

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Two Generations of Cascade Mountains

• Western Cascades
• Older (began erupting around 40 mya)
• Mostly stratovolcanoes
• Extinct (they make up the western foothills of
  the High Cascades)

• High Cascades
• Younger (began erupting 3-5 mya)
• Mix of all 3 types of volcanoes
• Many are still active
• Create a rain shadow effect

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The Rain Shadow Effect

• Majority of Oregons precipitation comes from the
  Pacific Ocean and heads in an easterly direction
• As clouds encounter the Cascades, they are forced
  higher
• This typically cools the moisture in the clouds,
  causing it to condense into rain, snow, etc.
• The precipitation thus falls on the western side
  of the Cascades and on the Cascades themselves,
  leaving the eastern side of the state much drier

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The Rain Shadow Effect
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Mt. Jefferson as seen from Mt. Hood
Note the windblown trees
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Mt. Hood see how mudflows and glacial runoff
have carved the landscape
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Timberline Lodge why is it called this?
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Timberline Lodge

• Timberline Lodge is at an elevation of about 6000
  feet, very close to the timberline for Mt. Hood
• Timberline refers to the elevation on a
  mountain above which trees will not grow

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Timberline
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Bibliography

• Topinka, Lyn. Visit a Volcano - Cascade Range
  Volcanoes. USGS. January 9, 2006 lthttp//vulcan.w
  r.usgs.gov/Volcan oes/Cascades/ImageMaps/CascadeRa
  nge/cascade_range.htmlgt. 
• Tropical Ecology Costa Rica. Westminster
  College. Jaunuary 9, 2006 lthttp//www.westminste
  r.edu/staff /BIO520/CR/Lecture.htmgt.