Tectonic plate

The ground beneath us appears still, but Earth’s outer layer is divided into large tectonic plates that move slowly relative to one another. Plate tectonics explains how this movement changes Earth’s surface and produces earthquakes and volcanic activity.

The lithosphere is the rigid outer shell. It includes both the crust and the rigid uppermost mantle. It is broken into tectonic plates, so a plate is not simply a piece of crust.

The crust and the rigid uppermost mantle together form the lithosphere. This is broken into large slabs called tectonic plates. A plate therefore includes mantle rock as well as crust.