Geology: Earth's Origin and Structure
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Questions and Answers

What is the study of Earth's structure and composition?

  • Meteorology
  • Oceanology
  • Geology (correct)
  • Astrology
  • What is the process that occurred from the compression of the dust and gas in the cloud?

  • Gravitational attraction
  • Radioactive decay
  • Hydrogen fusion (correct)
  • Nuclear fission
  • What is the shape of the Earth according to the text?

  • A perfect sphere
  • A prolate spheroid
  • An oblate spheroid (correct)
  • A irregular shape
  • What is the composition of the inner core?

    <p>Solid iron and nickel</p> Signup and view all the answers

    What is the reason for the decrease in the Earth's heat over time?

    <p>The decrease in the heat loss rate of certain rocks</p> Signup and view all the answers

    What is the source of the electric current that forms the Earth's magnetic field, according to a hypothesis?

    <p>The liquid iron in the Earth's core</p> Signup and view all the answers

    What was the evidence that Alfred Wegener used to support his theory of continental drift?

    <p>The fossils of the Mesosaurus found in both Africa and South America</p> Signup and view all the answers

    What is the characteristic of the rocks found at mid-ocean ridges?

    <p>They change polarity every time the Earth's magnetic field reverses</p> Signup and view all the answers

    What is formed at a divergent boundary?

    <p>A rift valley</p> Signup and view all the answers

    What is the characteristic of the rocks around the Mid-Atlantic Ridge?

    <p>They are hotter than the rocks further away</p> Signup and view all the answers

    Study Notes

    Geology

    • Study of Earth's structure and composition

    Origin of the Solar System

    • The Nebular Hypothesis suggests that the sun formed from a swirling cloud of dust and gas around 4.6 billion years ago
    • As the cloud shrank, rotation increased due to gravity, leading to hydrogen fusion and heating

    Earth's Size and Shape

    • The spinning motion of Earth formed a bulge, making it an oblate spheroid, not a perfect sphere
    • Measuring the weight of objects in different places shows that Earth is not spherical
    • Weight of objects tends to be heavier near the Earth's poles

    Earth's Interior

    • Collision of material left over from the solar system's formation led to the formation of Earth's cores and layers
    • Inner core: solid iron and nickel
    • Outer core: liquid iron and nickel
    • Mantle: iron, silicon, and magnesium; Earth's thickest layer
    • Crust: outermost layer, where life has been found
    • Lithosphere: upper mantle and lower crust, floating above the asthenosphere

    Earth's Heat

    • Factors contributing to Earth's heat: decay of radioactive isotopes, weight of materials, and meteorite impacts
    • Earth's heat has been decreasing since its formation due to rock thickness, heat loss rate, and percentage of radioactive materials

    Earth's Magnetic Field

    • Hypothesis: liquid iron in Earth produces an electric current, leading to the formation of the planet's magnetic field

    Early Plate Tectonics

    • Theory: the formation and movement of the Earth's crust
    • Early explorers noted the movement of continents by comparing Africa's coast with east South America
    • Alfred Wegener proposed that continents have been drifting apart, using the Mesosaurus as evidence

    Modern Plate Tectonics

    • Discoveries of magnetism and sea floor age provided evidence for plate movement
    • Scientists revised Wegener's theory, adding that plates are part of a lithospheric plate covering the Earth's surface
    • Volcanoes and earthquakes occur in concentrated belts at theoretical plate boundaries

    The Ocean Floor

    • Igneous rocks of the ocean floor are magnetic, providing information about plate movement
    • Mid-ocean ridges show rocks changing polarity with each magnetic field reversal, indicating plate movement
    • Rocks near the ridge are hotter than those further away

    Divergent Boundaries

    • Two lithospheric plates are pulling apart, forming rift valleys
    • Fracture zones line the boundary where a fault lies perpendicular to the divergent boundary
    • The crust is pulled apart, forming a new ocean floor
    • Example: Mid-Atlantic Ridge

    Convergent Boundaries

    • A place where two plates are moving towards each other

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    Description

    Learn about the Nebular Hypothesis, the formation of the Sun and Earth, and the planet's size and shape in this geology quiz.

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