Discussion Questions

Lesson 1 "The Earth's Layers"

Discussion Questions
  1. How did Andrija Mohorovicic discover that the Earth's crust is made of less dense rock than the mantle.
    By studying earthquake waves. The waves moved at different speeds through the different layers The speed of movement through the crust was much slower than through the mantle. This meant that the crust was less dense and had to be made of a different material than the mantle.

  2. Write in your own words the definition of a discontinuity.
    A discontinuity is the boundary between the layers of the Earth.
  3. Name the four layers of the Earth in order from the outside to the center of the Earth.
    1.Crust 2. Mantle 3. Outer Core 4. Inner Core

  4. What causes the mantle to "flow"?
    The mantle flows because of convection currents that are caused by very hot material in the mantle rising, cooling, and then sinking. This circular pattern causes the mantle to flow.

  5. What are the two main metals that make up the outer and inner core?
    Nickel and Iron

  6. Describe in your own words how the Earth's layers were formed. Card 2 "The Four Layers" will help you.
    As the Earth cooled the densest, heaviest materials sank to the middle of the Earth. The lightest materials rose to the top. This material was made mostly of rock. Rock makes up the crust of the Earth. Denser rock makes up the mantle. The most dense materials, iron and nickel, make up the inner and outer core.

Answer Key

Lesson 2 "Pangaea to the Present"

Discussion Questions

  1. In your own words explain what the Continental Drift Theory states.
    The Earth's plates are moved very slowly, 1-4 inches per year, by convection currents emanating from the mantle. These plates have been moving for millions of years and continue to move today.

  2. How did Alfred Wegener try to prove that the continents of Africa and South America were once connected.
    Alfred Wegener discovered that the magnetic bands in rocks from South America did not point to the north pole as they should. If these rocks were moved to the position that Wegener though they were created then they did point to the north pole. He also matched rocks from Africa and South America for mineral content and age.

  3. How did the ancient people of Japan explain earthquakes?
    The Japanese explained that earthquakes were produced by a giant catfish called Namazu. This catfish lived under the Earth's surface and shook very violently when it was not kept under control by the god Kashima.

  4. How did the ancient Romans explain the presence volcanoes.
    Vulcan, the god of weapons, used the volcanoes off the coast of the Roman Empire as his forge.
  5. What caused Pangaea to break up?
    Pangaea split apart for the same reason that the plates are moving today. Convection currents in the mantle move the plates of the Earth at 1-4 inches per year.

  6. What is the Continental Drift Theory?
    The continental drift theory states that the plates of the Earth are moving at 1-4 inches per year. This movement is caused by convection currents in the mantle. The continents have been moving into their present position for about 250 million years. They were once joined into one huge continent called Pangaea.
  7. What happened at the Triple Junction? Where is it located today?
    The triple junction was a tear in the Earth's crust that allowed massive amounts of lava to pour out. This zone was located in west central Africa and eastern South America. Geologists use this junction to prove that the two continents of South America and Africa were joined at one time. The rocks located in these regions are identical for mineral content and age.

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