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Window for first test (Chapters 1-4) opens Monday; Lecture on Monday will finish Chapter 4.

Kauai. Window for first test (Chapters 1-4) opens Monday; Lecture on Monday will finish Chapter 4. There will be time on Monday for questions. 1. Kauai. 2. Waimea Canyon, Kauai, HI. 3. 4. Big Island is Earth’s largest volcano. “hotspot” explanation for Hawaiian Island chain. 6.

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Window for first test (Chapters 1-4) opens Monday; Lecture on Monday will finish Chapter 4.

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  1. Kauai Window for first test (Chapters 1-4) opens Monday; Lecture on Monday will finish Chapter 4. There will be time on Monday for questions. 1

  2. Kauai 2

  3. Waimea Canyon, Kauai, HI 3

  4. 4

  5. Big Island is Earth’s largest volcano “hotspot” explanation for Hawaiian Island chain 6

  6. Summit of Olympus Mons is 27 km (88,000 ft) above the mean elevation of Mars’ surface. Caldera is 85 km long and 50 km wide. Why is this Martian shield so much larger than shield volcanoes on Earth? No lateral movement of plates. Think of Mars as a one-plate planet. Olympus Mons

  7. Hot spots lie above mantle plumes. These plumes (like plate movements) are examples of convection.

  8. Giants Causeway, Northern Ireland

  9. columnar basalt

  10. columnar basalt

  11. Nearly all of the seafloor is underlain by basalt. Did it all come from a hotspot? No Seafloor spreading; The action is at divergent plate boundaries.

  12. Pillow basalt-- distinctive blobby shape; forms during underwater eruptions http://www.youtube.com/watch?v=DS1Br1A2FnU

  13. pillow basalt on sea floor

  14. Pillow basalt, New Zealand Pillow basalt, South Pass, Wyoming (more than 2 billion years old)

  15. 2 major kinds of magma: silica contenttemperature Basaltic 50% 900-1200C thin, fluid shield volcanoes gases escape “quiet, safe” Granitic 60-70% 800 C or less (or Silicic) thick, viscous composite volcanoes traps gases violent eruptions

  16. increasing SiO2

  17. basaltic magma Falling pressure allows melting High-silica (granitic) magma Release of water aids melting

  18. Composite volcanoes are steep-sided and violent. They are produced by high-silica magmas. They are composed of alternating lava flows and pyroclastic material.

  19. Seattle Pacific Ocean Mt. Rainier Columbia River Mt. St. Helens Mt. Adams Mt. Hood Composite volcanoes of the Cascade Range, OR & WA

  20. Mt. Rainier (foreground), Background: Mt. Adams to the left, St. Helens to right

  21. Image of Mt. Rainier from hand-held camera

  22. Mt. St. Helens, WA; note where lateral blast took place in 1980

  23. Crater Lake, OR (about 5 miles in diameter)

  24. What kind of magma generated the eruption at Crater Lake? Relatively cool and viscous; high SiO2 Relatively cool and fluid; high SiO2 Relatively hot and fluid; low SiO2 Relatively hot and viscous; low SiO2 Relatively hot and viscous; no SiO2

  25. Ash flows Gravity-driven density currents Fast-moving (more than 100 km/hr) and deadly Hot mixture of ash and air Can move as far as 100 km

  26. Ash flow Eruption of Sarychev Volcano (Russia, just NE from Japan) Photo by astronaut aboard International Space Station, June 12, 2009 more info

  27. northern New Mexico The thicknesses and extents of ancient ash flows are awesome. No similar event has been witnessed during historic times.

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