Map of the Word with lines marking boundaries of tectonic plates. Plate tectonics is a theory that explains how Earth’s lithosphere—its upper mantle and crust—is split into sections called ...

Plate tectonics is the theory that Earth's outer layer is made up of plates, which have moved throughout Earth's history. The theory explains the how and why behind mountains, volcanoes ...

According to plate tectonics theory, Earth's outer shell is divided into multiple plates that slowly glide over the mantle. This slowly changes Earth's surface over time by merging, or separating ...