Grade 7 Earth Science: Earth's Interior Exploration
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Questions and Answers

How do scientists primarily explore and map the hidden layers beneath Earth's surface?

  • Using seismic waves (correct)
  • Deploying satellites
  • Conducting chemical analysis
  • Drilling boreholes
  • What is the main factor that influences the speed and direction of seismic waves traveling through the Earth?

  • Distance from the Earth's surface
  • Density and composition of materials encountered (correct)
  • Temperature of the Earth's core
  • Magnetic field variations
  • In comparison to the Earth's radius, how deep have humans managed to burrow into the Earth's surface?

  • 4,000 miles
  • 12 kilometers (correct)
  • 20 kilometers
  • 5,000 miles
  • What technique is used by geologists to map the boundaries between Earth's layers based on changes in seismic wave behavior?

    <p>Seismic tomography</p> Signup and view all the answers

    What is the crust of the Earth defined as?

    <p>The outermost layer of the Earth</p> Signup and view all the answers

    Why are seismic waves likened to a 'unique song' as they travel through Earth's layers?

    <p>Due to revealing clues about hidden structures below</p> Signup and view all the answers

    What is the approximate thickness of the Earth's oceanic crust?

    <p>7 kilometers</p> Signup and view all the answers

    Which layer of Earth's crust contains the asthenosphere?

    <p>Upper Mantle</p> Signup and view all the answers

    Who discovered the Mohorovičić discontinuity in 1909?

    <p>Andrija Mohorovičić</p> Signup and view all the answers

    Which layer of Earth's interior contributes to convection and heat transfer?

    <p>Lower Mantle</p> Signup and view all the answers

    In terms of volume, which layer of Earth accounts for the largest percentage?

    <p>Mantle</p> Signup and view all the answers

    What percentage of Earth's mass does the core account for?

    <p>31%</p> Signup and view all the answers

    What drives plate tectonics and volcanic activity according to the text?

    <p>Heat from the core</p> Signup and view all the answers

    Who championed the theory of continental drift?

    <p>Alfred Wegener</p> Signup and view all the answers

    What was the supercontinent proposed by Alfred Wegener called?

    <p>Pangaea</p> Signup and view all the answers

    What does 'Pangea' mean when broken down into its parts?

    <p>'Universal land'</p> Signup and view all the answers

    During which geological eras did Pangea exist?

    <p>Early Paleozoic to Mesozoic</p> Signup and view all the answers

    What did Wegener's theory of continental drift propose regarding the continents?

    <p>They were once joined in a supercontinent and later drifted apart.</p> Signup and view all the answers

    What did the geological formations in continents like Africa, South America, India, and Australia show signs of?

    <p>Ancient glaciation</p> Signup and view all the answers

    What did the similar glacial striation patterns on separated continents imply?

    <p>Shared glacial history on a single, larger landmass</p> Signup and view all the answers

    What was Wegener's theory challenged by?

    <p>A lack of explanations for continental movement forces</p> Signup and view all the answers

    What mechanisms did Wegener propose to explain continental movement?

    <p>Tidal forces and polar-fleeing forces</p> Signup and view all the answers

    Why couldn't Wegener explain how continents could move across the Earth's surface?

    <p>Limitations in understanding ocean floor structures</p> Signup and view all the answers

    Despite the challenges faced by Wegener's theory, what is still happening to continents?

    <p>They are slowly moving</p> Signup and view all the answers

    What inspired Wegener to develop his theory of continental drift?

    <p>The resemblance of certain continents' coastlines.</p> Signup and view all the answers

    Why was the similarity in coastlines of South America and Africa significant?

    <p>It suggested a deep physical connection between the continents in the past.</p> Signup and view all the answers

    What was a significant puzzle in terms of fossil evidence for continental drift?

    <p>Identical fossils found across continents now separated by oceans.</p> Signup and view all the answers

    How did geologic features provide evidence for continental drift?

    <p>Identical mountain ranges across continents.</p> Signup and view all the answers

    Why were the Appalachian Mountains mentioned in the text?

    <p>To indicate their relation to mountains in Scotland and Scandinavia.</p> Signup and view all the answers

    What common aspect did mountain ranges in North America, Scotland, and Scandinavia share?

    <p>Their ages, structures, and rock types were similar.</p> Signup and view all the answers

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