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Volcanoes

Volcanoes. Formed at Plate Boundaries. Ring of Fire!. Some Volcanoes form at Hot Spots. Examples: Hawaii and Yellowstone. 3 Types of Volcanoes. Shield Volcano Composite ( Strato ) Volcano Cinder Cone Volcano. Types of lava and eruptions.

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Volcanoes

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  1. Volcanoes

  2. Formed at Plate Boundaries Ring of Fire!

  3. Some Volcanoes form at Hot Spots Examples: Hawaii and Yellowstone

  4. 3 Types of Volcanoes Shield Volcano Composite (Strato) Volcano Cinder Cone Volcano

  5. Types of lava and eruptions Mafic Lava: Rich in magnesium and poor in silica. Erupts generally quietly and is not viscous (flows easily. Dark color. (Example: Mauna Loa in Hawaii). Felsic Lava: Rich in silica and poor in magnesium. Erupts violently with pyroclastic flows and ash. Light color. Very viscous. (Example: Mt. Vesuvius and Mt. St. Helens.)

  6. Shield Volcano • Broad with gently sloping sides. • Quiet eruptions with mafic lava • Usually the lava hardens into Basalt, which makes up the ocean floor. • Largest volcano • Example: Mauna Loa in Hawaii

  7. Cinder Cone Volcano • Very steep slopes • More felsic and explosive eruptions. • The cinders of volcanic rock (scoria, pumice) are deposited to form a cone. • Example: Mauna Kia in Hawaii

  8. Composite Volcano/Stratovolcano • Tall and steep • Alternating layers of lava flows and pyroclastic material (ash). • Mostly explosive eruptions due to felsic magma though some quiet lava flows. • Very Viscous lava • Examples: Mt. Fuji in Japan and Mt. St. Helens in Washington State.

  9. Calderas Yellowstone is an example of a caldera type eruption

  10. Volcanoes from Rifting Plates • When plates diverge, magma can rise up and form a rift-volcano. • Examples: Mid-Atlantic Ridge and African Rift Valley.

  11. Flood Basalts: Well that’s weird. • 17-12 Million Years ago, miles long rifts in Washington and Oregon erupted huge flows of basalt. • Called Flood Basalts. • Geologists not really sure why it happened.

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