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CHAPTER 3 SECTION 1

• VOLCANOES AND PLATE TECTONICS

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WHAT IS A VOLCANO

• A WEAK SPOT IN THE CRUST WHERE MAGMA COMES
  THROUGH.
• EXAMPLES- MID OCEAN RIDGE, RING OF FIRE.

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LOCATION OF VOLCANOES

• AT BOUNDARIES -WEAKENED PARTS OF THE CRUST
• DIVERGENT BOUNDARIES- ALONG THE MID OCEAN RIDGE
• CONVERGENT BOUNDARIES- WHERE OCEANIC AND
  CONTINENTAL CRUST COLLIDE AND TRENCHES ARE FOUND
  (AREAS OF SUBDUCTION)

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DIVERGING PLATE VOLCANOES

• ALONG THE MID OCEAN RIDGE
• LONGEST MOUNTAIN RANGE LY COMES TO THE SURFACE IN
  ICELAND AND THE AZORESON THE EARTH- ON

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CONVERGING PLATE VOLCANOES

• WHEN PLATES COLLIDE THE MORE DENSE PLATE SUBDUCTS
  GOES UNDER THE LIGHTER PLATE AND IS MELTED THE
  RESULTING INCREASE IN PRESSURE CAUSES THE MAGMA
  TO SEEP OUT.

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SUBDUCTION- PLATES

• TWO OCEANIC PLATES COLLIDE THE OLDER DENSER PLATE
  WILL SUBDUCT- ALEUTIAN ISLANDS
• AN OCEANIC AND A CONTINENTAL PLATE CONVERGE- THE
  OCEANIC PLATE IS MORE DENSE AND IS PULLED DOWN
  AND REMELTED

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HOT SPOTS

• A PLACE IN THE AESTHENOSPHERE WHERE THE MAGMA IS
  SO HOT IT MELTS THROUGH THE LITHOSPHERE LIKE A
  BLOW TORCH ALLOWING THE MAGMA TO FLOW
  THROUGH-VOLCANO- HAWAIIAN ISLANDS

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• Review and reinforcement
• 1. In what way are volcanoes a constructive
  force?
• 2. Why do so many of Earths volcanoes occur
  along plate boundaries?
• 3. Explain how the hot spot shown in the diagram
  above created the Hawaiian

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• Islands. Draw an arrow on the diagram to help
  explain the process.
• u Building Vocabulary
• Answer the following questions on a separate
  sheet of paper.
• 4. What is the difference between magma and lava?
• 5. Define each of these terms in your own words.
• a. volcano b. Ring of Fire c. island arc
• Pacific Ocean
• Pacific Plate
• Hawaiian Islands
• Hot Spot