Plate tectonics is the framework that explains the large-scale motion of Earth's rigid outer shell. The lithosphere is broken into plates that move over the weaker asthenosphere and interact at divergent, convergent and transform boundaries.
What the science says
At divergent boundaries, plates move apart and new crust can form, as at mid-ocean ridges. At convergent boundaries, one plate may descend beneath another in a subduction zone or continents may collide. Transform boundaries accommodate mainly horizontal sliding.
How the process works
Plate motion is driven by a combination of forces associated with Earth's internal heat, including the pull of dense subducting slabs and gravitational forces related to elevated ridges. The system is coupled to mantle convection but is not simply plates riding on circular conveyor belts.
What scientists measure
Plate tectonics explains why earthquakes, volcanoes, mountain belts and ocean basins are concentrated in characteristic patterns. Magnetic stripes on the seafloor, earthquake locations and direct GPS measurements provide strong evidence for plate motion.
Limits and open questions
Plates move only centimeters per year, yet over millions of years that motion reorganizes continents and oceans. The theory links processes that once seemed unrelated into one testable model of an active planet.
Why this topic matters
Understanding What Is Plate Tectonics helps connect individual observations to the larger scientific framework. Reliable explanations separate measured evidence from speculation, make uncertainty visible, and give readers a basis for interpreting new research as it appears.
