The Earth in Motion: Plate Tectonics, the Earth’s Interior, and Geologic Hazards

As you have learned in the previous chapter, the careful and continuous application of science can lead to new ideas. When enough evidence is collected for these ideas through rigorous observation, experimentation, testing, and debate, that idea becomes a theory.

There have been many theories that have completely redefined how we view ourselves, our planet, and our universe. There is Charles Darwin’s Theory of Evolution, or the Big Bang Theory, which states the Universe formed an astonishing 13.8 billion years ago, and Einstein’s Theory of General Relativity. You don’t have to understand every detail of these theories to know that they have changed our world and society.

The groundbreaking theory that revolutionized geosciences was the understanding that our continents were once in a far different place than they are on today’s world map. This realization came with a lot of controversy and debate until we arrived at a theory that could neatly explain many geological processes, including why volcanoes and earthquakes happen where they do–we call this the theory of Plate Tectonics.

Image of the world map appearance over the past 250 million years.
Figure 2.1. These globes display what we now think the world looked like over the past 250 million years. What caused the continents to move?


After reading this chapter, you should be able to…

  • Describe the physical and chemical properties of the layers in Earth’s interior.
  • Explain the current theory of plate tectonics and provide supporting scientific evidence for this concept.
  • Describe the plate boundary types and how each shape distinct landforms.
  • Identify real-world examples of plate boundaries.
  • Explain how plate boundaries connect to the distribution of geologic hazards.


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Dynamic Planet: Exploring Geological Disasters and Environmental Change Copyright © 2021 by Charlene Estrada, Carolina Michele Londono, Merry Wilson is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License, except where otherwise noted.

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