22 6

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22 6

  1. 1. Ch 22-6
  2. 2. Landform creation <ul><li>Volcano – Pressure forces magma and gasses out to the surface. </li></ul><ul><ul><li>When magma reaches the surface it is called lava </li></ul></ul><ul><ul><li>This process creates mountains and islands </li></ul></ul><ul><ul><li>Archipelago </li></ul></ul>
  3. 3. Two Types of Eruptions <ul><li>Quiet Eruptions </li></ul><ul><li>Very hot and fluid lava </li></ul><ul><li>Sheild Volcanoes </li></ul><ul><li>Pahoehoe fast moving smooth lava </li></ul><ul><li>Aa is slow moving chunky lava </li></ul><ul><li>Explosive Eruptions </li></ul><ul><li>Thick magma, moves slowly causing pressure to build </li></ul><ul><li>Cinder cone, composite volcanoes </li></ul><ul><li>Lava cools very quickly </li></ul>
  4. 4. Explosive Eruption
  5. 5. Composite Volcano A volcano that forms from explosive eruptions that produce lava and ash. They are tall and steep, often with second vents
  6. 6. Composite Volcano
  7. 7. Mount St. Helens was an explosive eruption
  8. 8. Cinder cone An explosive ash and cider eruption that results in a small, Steep-sided volcano
  9. 9. Crater Lake, Or Is an example of a Cinder Cone
  10. 10. Sheild Volcano A quiet eruption of fast moving lava produces a wide, gently sloping or flat volcano
  11. 11. Lava Flow in Hawaii
  12. 12. Volcano Formation <ul><li>Volcanoes usually form along converging plate boundaries or at hot spots. </li></ul><ul><li>Hot spot is a region where a pocket of hot rock extends from within the mantle to near the surface. </li></ul><ul><li>Ring of fire – pacific plate boundary where many volcanoes and earthquakes occur. </li></ul>
  13. 13. A convergent plate boundary
  14. 14. Hot Spots <ul><li>Volcanoes form over spots in the surface where magma comes out, but not on a fault line. </li></ul><ul><li>As the plate moves old volcanoes become dormant and new ones form. </li></ul><ul><li>This is how archipelagos are created. </li></ul>
  15. 15. Hawaii is an archipelago.
  16. 16. Yellowstone is over a hot spot
  17. 17. The ring of fire
  18. 18. Other features <ul><li>Sometimes magma cools before it reaches the surface. This creates igneous rock formations </li></ul><ul><li>Batholith, sill, dike and volcanic neck are examples </li></ul>

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