Inside Earth Chapter 3.1 Pages 88-92

1. Volcanoes & Plate Tectonics Inside Earth Chapter 3.1 Pages 88-92

2. What is a Volcano? • A weak spot in the crust where molten material, or magma comes to the surface • Volcanic Activity is a constructive force that adds new rock to existing land or forms new islands.

3. Volcano Menu Crater Lava Vent Volcano Erupts Lava Flow Pipe Magma Rising Magma Chamber Magma

4. Magma / Lava Volcano Menu • Magma: melted rock, gases and water vapor from the mantle. Below the surface • Lava: magma that reaches the surface • Cools and forms solid rock.

5. Why does Magma Rise? Volcano Menu • Magma is a liquid, so it is less dense than the solid material around it • Flows upward into cracks in the rocks above • Rises until it reaches the surface or becomes trapped beneath layers or rocks.

6. Volcano Erupts Volcano Menu Dissolved gases trapped in magma are under tremendous pressure Eruption occurs when the gasses rush to the surface, carrying magma with them.

7. Crater Volcano Menu Lava collects in the Crater: the bowl-shaped area that forms around the volcano’s vent.

8. Vent Volcano Menu The point on the surface where magma and gas leave the volcano’s pipe.

9. Pipe Volcano Menu A narrow, almost vertical crack in the crust through which magma rises to the surface.

10. Magma Chamber Volcano Menu A large underground pocket of magma that is made from magma rising to the surface.

11. Lava flow Volcano Menu The river of lava that pours down a volcano over the land.

12. Exit Pass Describe two different features of a volcano.

13. Divergent Boundaries • Form along the mid-ocean ridge • Lava pours out of the cracks in the ocean floor • Iceland is a volcano on the mid-ocean ridge that has reached the surface.

14. Convergent Boundaries • Plates collide • Denser plate subducts towards the mantle. • Forms a deep-ocean trench • The crust melts and forms magma that rises • Rising magma erupts through a volcano on the surface.

15. Convergent Boundaries • Ocean/Ocean • Denser ocean plate subducts • Forms a deep sea trench • Forms an island arc of volcanoes • Japan • New Zealand • Aleutians

16. Convergent Boundaries • Continent to Ocean • Dense ocean plate subducts • Forms a deep sea trench • Forms volcanoes on the land • Mt. St Helens • Andes Mountains in S. America

17. Stages of a Volcano • Active: • A live volcano that is erupting or shows signs that it may erupt in the future • Dormant: • A sleeping volcano. It may awake in the future and become Active • Extinct: • A dead volcano. It is unlikely to erupt again.

18. Location of Volcanoes Most occur along diverging boundaries such as the Mid-Ocean Ridge or in subduction zones.

19. Location of Volcanoes • About 600 active volcanoes on land, more lie beneath the sea. • Ring of Fire formed by the many volcanoes that rim the Pacific Ocean.

20. Hot Spot Volcanoes • An area where magma from deep within the mantle melts through the crust like a blow torch • Lie in the middle of plates • Yellowstone formed under the continent • The plate travels over the hot spot • Created a chain of islands to form Hawaii

21. Hot Spot Volcanoes

22. Exit Pass What are the 3 stages of a volcano’s life? Explain one of them.

23. 1 Ash Cloud 7 Lava Flow 2 Crater 3 Vent Magma Chamber 6 5 Pipe 4 Sill

24. What to Work On • Read pages 88-92 in the textbook • Answer the Section 3.1 Review questions on page 91 (#’s 1-4) DUE: Friday, November 4th

25. Project Topics • Iceland • Hotspots (Hawaii) • San Andreas Fault • Tau Tona mine • Mount St. Helens • Deep-sea Vents • Christchurch, Australia earthquake • Magnetic stripes / field • Coral reef atolls • Landslides • Liquefaction • Sinkholes • Satellite mapping • Grand Canyon