What is the primary cause of plate tectonics?

Plate tectonics is primarily driven by convection currents in the Earth's mantle. The mantle, which is the layer of the Earth located beneath the crust, behaves as a viscous fluid over geological time scales. These convection currents are generated by the heat from the Earth's core. As hot material from the lower mantle rises toward the surface, it cools and sinks back down, creating a cyclical motion. This movement produces forces that can cause the tectonic plates at the Earth's surface to move, interact, and change position over time.

The dynamics of these convection currents are critical because they not only facilitate the movement of the plates but also influence geological events such as earthquakes and volcanic activity. Understanding mantle convection is essential for comprehending how continental drift and plate interactions occur, making it the main driving mechanism behind the theory of plate tectonics.