The theory of plate tectonics explains the past and current movements of the rocks at Earth's surface (lithospheric plates) and provides a framework for understanding its geological history. Plate movements are responsible for most continental and ocean floor features and for the distribution of most rocks and minerals within Earth's crust.
The Theory of Plate Tectonics
The theory of plate tectonics states that the Earth's solid outer crust, the lithosphere, is separated into plates that move over the asthenosphere, the molten upper portion of the mantle. Oceanic and continental plates come together, spread apart, and interact at boundaries all over the planet.
Key Points
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Map Representing the Direction and Speed of Some Major Tectonic Plates
Are WE moving right now?The North American plate is moving to the west-southwest at about 2.3 cm (~1 inch) per year driven by the spreading center that created the Atlantic Ocean, the Mid Atlantic Ridge. So, if you are 12 years old your entire neighborhood and the United States of America has moved about one foot since you were born! Imagine what would happen over 100 years, 1,000 years, a million years, or billions of years!?
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Summary of Plate Boundaries, Geologic Activities and
Landform Changes due to Plate Tectonics
Video Guide:
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Video Guide:
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Topic Tips
- The theory of plate tectonics explains most of the geologic activities and landform changes that occur on the surface of the Earth.
- Plate tectonics has and will continue to change the surface of the Earth and the organism that live there.
- There is a lot of evidence to support the theory of plate tectonics that we will explore more in the next module.