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Published byMarilyn McCoy Modified over 9 years ago
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7. Volcanoes of the Cascade Range.
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Vineyard Mt., Larch Mt., Mary’s Pk.
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Corvallis ActiveDormant Extinct
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7. What Oregon volcano is still considered active (erupted in last 200 years)? 7. Answer: Mt. Hood
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Mt Hood is an active stratovolcano!
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solid Upper Mantle plastic What is in the crust? 47% Oxygen 28% Silicon 8% Aluminum 5% Iron 4% Calcium 3% Magnesium 2% Sodium Crust Continental crust is thicker and less dense than oceanic crust. The Crust is made of solid plates that “float” on the Mantle.
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8. What are the two most common chemical elements in the earth’s crust? 8. Answer: Oxygen (47%) and Silicon (28%)
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8a. What are the two most common chemical elements in lava? 8a. Answer: Oxygen (47%) and Silicon (28%)
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Mt Saint Helens – April 1980
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Mt. St. Helens Eruption in May 1980
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Cartoon by Sidney Harris
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Mt Saint Helens – June 1980
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Belknap Crater Little Belknap Shield volcanoes in the Cascades This lava flow came from Little Belknap 1300 years ago.
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Lava Flow at McKenzie Pass A’a’ – blocky lava
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9. What type of volcano is this? Mt Jefferson is an extinct stratovolcano
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A 4 inch “bulge” (probably caused by magma) has developed over the last 4 years on the west side of South Sister. (as of 2004) ERUPTION LIKELY?
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Earthquake activity by year at Three Sisters showing depth
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NASA photo October 1994
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Could South Sister Erupt Soon?
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Possible Hazards from an Eruption of South Sister - USGS
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Corvallis Eugene Bend
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8. Summary – Oregon’s complete geologic map.
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Complete surface geologic map of Oregon…very complex!!!
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Cartoon by Sidney Harris
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Where was this photo taken?
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Acknowledgement: USGS, Volcanoes Web Site, Geology of Oregon, and other public web sites for diagrams and photos
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