Earth Science

Plate Tectonics

Plate Tectonics through Earth History

Study Tip
Imagining the motion of converging, diverging, and transform plates can help you memorize what happens as a result.

Overview

  • Earth’s outer shell is composed of plates that are constantly in motion. This motion affects the rock cycle, climate, and the evolution of life.
  • Plate tectonics: The movement of Earth’s plates. The motions affect Earth’s rock cycle, climate, and the evolution of life.
  • Lithosphere: The layer of solid, brittle rock that makes up the Earth's surface; the crust and the uppermost mantle. This is where Earth’s plates are located.
Study Tip
Imagining the motion of converging, diverging, and transform plates can help you memorize what happens as a result.
Study Tip
The same way a person may cast a shadow over another person when they stand under the sun, planets or celestial bodies that have aligned themselves cast shadows over one another as well.

Plate Tectonics Theory

  • Plate tectonics theory explains why:
  • Earth’s geography has changed over time and continues to change today
  • Certain regions are more prone to earthquakes
  • Certain regions are more prone to volcanic eruptions
  • Ore deposits are found in a specific location
  • Living and fossil species are found in as specific location
  • Plates move via convection within the Earth’s mantle and meet at plate boundaries where most geologic activity takes place (volcanoes, earthquakes, mountain building).
World map
Plate boundaries are areas where plates meet

Plate Boundaries

  • The features that form at a plate boundary are determined by the direction of plate motion and by the type of crust at the boundary.
  • Divergent plate boundaries: the two plates move away from each other. Valley is formed.
  • Convergent plate boundaries: the two plates move towards each other. Mountain is formed.
  • Transform plate boundaries: the two plates slip past each other. Earthquake occurs.
Concept Check
  • What are plate boundaries? Describe the three main types of plate boundaries.
  • What is the lithosphere?
  • Describe the plate tectonics theory.