Plate Tectonics and Continental Drift
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Questions and Answers

What is the primary theory that explains the movements of Earth's lithospheric plates?

  • Plate tectonic theory (correct)
  • Continuous motion theory
  • Continental drift theory
  • Ocean floor expansion theory

Which piece of evidence did Wegener use to support his hypothesis of continental drift?

  • Matching dinosaurs on different continents
  • Matching rock types on opposite sides of the Atlantic (correct)
  • The distribution of ocean currents
  • Identical mountain ranges found in different continents

What significant unanswered questions led to the initial rejection of Wegener's hypothesis?

  • What caused volcanic eruptions?
  • How do earthquakes occur?
  • How could continents form?
  • What forces could move continents? (correct)

What role did the ocean floor play in the development of plate tectonic theory?

<p>It helped answer questions about continental movements. (B)</p> Signup and view all the answers

What natural phenomena are supported by plate tectonic theory?

<p>Location of volcanoes and earthquakes (B)</p> Signup and view all the answers

The super continent proposed by Alfred Wegener is known as?

<p>Pangaea (A)</p> Signup and view all the answers

Which aspect did NOT contribute to the support of Wegener's hypothesis in subsequent research?

<p>Study of meteorological patterns (A)</p> Signup and view all the answers

Why did Wegener's hypothesis initially face skepticism in the scientific community?

<p>It did not explain the mechanism behind continental movement. (A)</p> Signup and view all the answers

Where do volcanic and seismic activities primarily occur?

<p>Along plate boundaries (D)</p> Signup and view all the answers

What do the earthquake and volcano belts provide support for?

<p>The theory of tectonic plate movement (A)</p> Signup and view all the answers

What technology was used to map the topography of the ocean floor in the 1940s and 1950s?

<p>S.O.N.A.R. (A)</p> Signup and view all the answers

How do rock samples from ocean ridges compare to those from deep-sea trenches?

<p>Ocean ridge rocks are younger (D)</p> Signup and view all the answers

What does paleomagnetism study?

<p>The history of Earth’s magnetic field (B)</p> Signup and view all the answers

What did scientists initially assume about the ocean floor before mapping it?

<p>It would be flat and uninteresting (A)</p> Signup and view all the answers

What is the approximate average age of sea floor rock?

<p>180 million years (B)</p> Signup and view all the answers

What phenomenon occurs when strain builds up at plate boundaries?

<p>Earthquakes (D)</p> Signup and view all the answers

What have magnetometers been used to measure around volcanoes?

<p>Variations in Earth’s magnetic field strength (A)</p> Signup and view all the answers

How do iron atoms in lava contribute to understanding Earth’s magnetic field?

<p>They become locked in place once the lava solidifies. (B)</p> Signup and view all the answers

What conclusion can be drawn from the magnetic records found on either side of mid-ocean ridges?

<p>Lithospheric plates are moving apart at these ridges. (B)</p> Signup and view all the answers

What happens to the age of rock as you move away from a mid-ocean ridge?

<p>The rock becomes older. (D)</p> Signup and view all the answers

What kind of record does basalt provide regarding Earth's magnetic field?

<p>A permanent record of the magnetic field at eruption time (D)</p> Signup and view all the answers

What feature of Earth's magnetic field has been observed from studies of basalt layers?

<p>It has flipped or reversed multiple times. (A)</p> Signup and view all the answers

What do scientists conclude about the patterns of magnetic reversals found in ocean floor data?

<p>They correlate with land-based basalt floor patterns. (B)</p> Signup and view all the answers

What is expected when measuring rock temperatures at various distances from a mid-ocean ridge?

<p>Temperatures will decrease as you move away from the ridge. (D)</p> Signup and view all the answers

Flashcards

Plate Tectonics

The theory that explains the formation, movement, and interaction of Earth's lithospheric plates.

Pangaea

A supercontinent that existed millions of years ago, consisting of all the present-day continents.

Lithosphere

The outermost rigid layer of Earth, comprised of the crust and upper mantle, broken into plates.

Continental Drift

The process by which the continents move apart due to the separation of lithospheric plates.

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Convergent Plate Boundaries

Areas where two lithospheric plates move towards each other, leading to collisions and mountain formation.

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Divergent Plate Boundaries

Areas where two lithospheric plates move away from each other, allowing magma to rise and create new crust.

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Transform Plate Boundaries

Areas where two lithospheric plates slide past each other horizontally, causing friction and earthquakes.

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Seafloor Spreading

The process of creating new oceanic crust at divergent plate boundaries.

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Earthquake and Volcano Belts

Areas on Earth where volcanic and seismic activity are concentrated. They occur along plate boundaries where plates meet, pull apart, or slide past each other.

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Plate Boundaries

Locations where two tectonic plates meet, interact, and cause significant geological activity.

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SONAR (Sound Navigation and Ranging)

A system that uses sound waves to determine the depth of the ocean.

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Mid-Ocean Ridges

Underwater mountain ranges that form along divergent plate boundaries where new oceanic crust is created.

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Deep-Sea Trenches

Deep trenches in the ocean floor that form at convergent plate boundaries where one plate subducts (slides) beneath another.

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Paleomagnetism

The study of Earth's past magnetic field by examining the magnetic properties of rocks.

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Magnetometers

Devices that measure the strength and direction of Earth's magnetic field. They are used to study the history of Earth's magnetic field.

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Magnetic Reversal Recording

The process of iron minerals in lava aligning with Earth's magnetic field as they cool, creating a permanent record of the field at that time.

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How do volcanoes provide evidence for plate tectonics?

Iron-bearing minerals in lava act like tiny compasses, aligning with the Earth's magnetic field, which can be studied in solidified basalt.

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Magnetic Reversals

The Earth's magnetic field has flipped its polarity multiple times throughout history, meaning the direction of the magnetic field has reversed. This is recorded in the iron-bearing minerals of solidified lava.

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Mirrored Magnetic Records

Magnetic field records on either side of mid-ocean ridges are mirror images of each other, supporting the idea that new ocean floor is created at these ridges as plates move apart.

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Ocean Floor Age

The age of the ocean floor increases progressively away from mid-ocean ridges, suggesting that new ocean floor is continuously created at the ridge and pushed outwards.

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How do volcanoes and seismic activity support plate tectonics?

Volcanic activity and seismic activity that create new ocean floor at mid-ocean ridges and cause earthquakes along plate boundaries are key evidence for plate tectonics.

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Magnetic Patterns on the Ocean Floor

Data collected on the ocean floor shows magnetic striping patterns that correspond to the magnetic reversal history found on land, supporting the theory of seafloor spreading.

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Temperature of Rocks Near Mid-Ocean Ridges

Rocks closer to mid-ocean ridges would be hotter than rocks further away, because new rock is constantly being created at the ridge and cools down as it moves away.

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Study Notes

Plate Tectonics

  • Earth's lithosphere is broken into plates that move
  • Plates move towards each other, away from each other, or slide past each other.
  • Plate tectonics explains the formation, movement, and interactions of these plates.

Continental Drift

  • Alfred Wegener proposed the theory of continental drift in 1912
  • Pangaea was a supercontinent that existed millions of years ago
  • Continental drift suggests the continents have moved to their current positions
  • Evidence supporting continental drift includes:
    • Puzzle-like fit of continents
    • Matching rock types on opposite sides of the Atlantic
    • Matching fossils on opposite sides of the Atlantic
    • Ancient climatic evidence suggesting large climate changes

Plate Tectonic Theory

  • Further evidence in the 1950s and 1960s, like earthquake, magnetism, and the age of rocks on the ocean floor, supported Wegener's hypothesis.
  • Plate tectonics states continents are part of lithospheric plates
  • The theory also explains the location of volcanoes and earthquakes.
  • It also describes the formation of new crust along the ocean floor.

Locations of Earthquakes and Volcanoes

  • Volcanic and seismic activity aren't random, occurring along belts.
  • These belts are often at plate boundaries, where plates meet
  • Plate boundaries are where plates meet, move apart, or slide past each other
  • High heat flow and magma movement can cause volcanic activity
  • Stress buildup and fractures cause earthquakes

Magnetism and the Age of the Ocean Floor

  • SONAR was used to map the ocean floor, revealing mid-ocean ridges and deep-sea trenches.
  • Rock samples from the ocean floor show that rocks near ridges are younger than those near trenches
  • Ocean floor rocks are significantly younger than continental rocks
  • Ocean floor rocks are usually around 180 million years old, while continental rocks can be as old as 3.8 billion years.

Magnetometers and the Ocean Floor

  • Magnetometers measured Earth's magnetic field strength around volcanoes
  • Magma/lava contains iron-bearing minerals that respond to Earth's magnetic field.
  • When lava solidifies into basalt, the iron atoms are locked into place, creating a record of the magnetic field.
  • Studying different layers of basaltic rock allows scientists to reconstruct Earth's magnetic field history.
  • Magnetic field flips, or reverses, over time, which is recorded in the ocean floor rocks.
  • The ocean floor rocks show a symmetrical pattern of magnetic reversals, supporting the idea of seafloor spreading and plate movement.

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Plate Tectonics PDF

Description

Test your knowledge on the theories of plate tectonics and continental drift with this quiz. Explore evidence, historical contexts, and the impact of ocean floor studies on our understanding of the Earth's lithosphere. Discover why Wegener's hypothesis faced skepticism and the implications of tectonic movements.

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