Paleomagnetism

Welcome to the eighth episode of the Plate Tectonics course! This episode builds upon our understanding of plate tectonics, continental drift, seafloor spreading, subduction, mountain formation, transform faults, and mantle convection, by introducing paleomagnetism. Paleomagnetism is the study of the record of the Earth's magnetic field in rocks, sediment, or archaeological materials. We will explore how certain minerals in rocks lock in a record of the direction and intensity of the magnetic field when they form. This episode explains how paleomagnetic data provided crucial evidence supporting the theories of continental drift and seafloor spreading, and how it continues to be a powerful tool for reconstructing past plate motions and understanding the Earth's magnetic field.

Check your understanding

These are the same multiple-choice questions you will see in the Quiz section after you listen to the episode. Use them here to preview or review the answers.

What is paleomagnetism?

  1. The study of ancient climates.
  2. The study of the Earth's magnetic field in the past, recorded in rocks.
  3. The study of fossils.
  4. The study of earthquakes.
  5. The study of volcanoes.
  6. The study of mountain formation

What is the Curie temperature?

  1. The temperature at which a rock melts.
  2. The temperature at which a mineral loses its magnetism.
  3. The temperature at which a mineral gains its magnetism.
  4. The temperature at which a rock forms.
  5. The temperature at the Earth's core.
  6. Room temperature.

What are apparent polar wander paths?

  1. The paths that migrating animals follow.
  2. The paths that magnetic north pole seems to have taken over time, based on paleomagnetic data.
  3. The paths of ocean currents.
  4. The paths of tectonic plates.
  5. The movement of glaciers
  6. The movement of magma underground

How did paleomagnetism support the theory of continental drift?

  1. By showing that the continents have always been in the same position.
  2. By showing that different continents had different apparent polar wander paths.
  3. By showing that the Earth's magnetic field has always been constant.
  4. By showing that volcanoes are randomly distributed.
  5. By dating fossils.
  6. By showing that all continents had the same polar wander path.

What are the magnetic "stripes" on the ocean floor evidence of?

  1. Ancient ocean currents.
  2. Seafloor spreading and magnetic field reversals.
  3. Underwater volcanoes.
  4. The movement of marine organisms.
  5. Tsunamis
  6. Underwater mountain ranges

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