Plate tectonics: the structure, processes, and effects of Earth's moving plates

Parts and characteristics

Each tectonic plate includes oceanic crust, continental crust, or both. Plates fit together like a jigsaw and interact along plate boundaries. The main types of boundaries are described below and illustrated in many educational sources such as educational pages:

• Divergent boundaries — where plates move apart and new crust forms, typically at mid-ocean ridges.
• Convergent boundaries — where plates collide, producing subduction zones or continental collisions that build mountain belts.
• Transform boundaries — where plates slide past one another, producing strike-slip earthquakes.

Driving mechanisms and current questions

Heat from Earth's interior supplies energy for plate motion. Several processes contribute: mantle convection, slab pull as a dense plate sinks into the mantle, and ridge push from elevated mid-ocean ridges. The relative importance and details of these mechanisms remain active research topics; summaries and scientific overviews can be found at research summaries and review articles.

History and development of the idea

Early observations that continents fit together led Alfred Wegener to propose continental drift in the early 20th century. The idea gained broad acceptance in the 1960s after discoveries of seafloor spreading, magnetic striping on the ocean floor, and a global pattern of earthquakes and volcanoes. These lines of evidence were integrated into the plate tectonics paradigm, which replaced earlier, less comprehensive models. For historical context, consult historical notes.

Importance and modern implications

Plate tectonics shapes Earth's long-term climate, controls the distribution of mineral and hydrocarbon resources, and underlies many natural hazards. Knowledge of plate interactions informs earthquake and volcanic hazard assessment, guides exploration, and helps interpret past continental arrangements and biological distributions. Comparative planetology considers why plate tectonics operates on Earth but appears absent or different on many other planets and moons; see comparative studies for more.

While the broad outlines of plate tectonics are well established, active research continues into coupling between mantle and plates, the initiation of plate boundaries, and tectonic behavior through Earth's history.