Plate tectonics is the scientific theory explaining that Earth's outer shell, called the lithosphere, is divided into several large and small rigid plates that slowly move over the more ductile layer beneath, the asthenosphere
. These tectonic plates include both continental and oceanic lithosphere and typically move at rates of a few centimeters per year
. The movement of these plates is driven primarily by convection currents in the mantle, where hot material rises and cooler material sinks, causing the plates to glide, collide, or pull apart at their boundaries
. There are three main types of plate boundaries based on their relative motions:
- Convergent boundaries , where plates move toward each other, often causing subduction (one plate sinking beneath another), mountain building, earthquakes, and volcanic activity.
- Divergent boundaries , where plates move apart, leading to seafloor spreading and the creation of new oceanic crust.
- Transform boundaries , where plates slide past each other horizontally, causing earthquakes
Plate tectonics explains many geological phenomena such as earthquakes, volcanic eruptions, mountain formation, and the distribution of continents and ocean basins. It also provides a framework for understanding Earth's geological history, including the movement of continents over millions of years
. In summary, plate tectonics is the theory that Earth's lithosphere is broken into moving plates whose interactions shape the planet's surface and geological activity
