The solid ground that we all live on forms a thin crust around the Earth. It’s no more than 50km thick - and it’s just the upper part of the lithosphere. Below it is the upper mantle. It’s mostly ...

Plate boundaries are where the action is. A large fraction of all earthquakes, volcanic eruptions, and mountain building occurs at plate boundaries. It is also where most of the people on Earth live.

From the deepest ocean trench to the tallest mountain, plate tectonics explains the features and movement of Earth's surface in the present and the past. The theory of plate tectonics was developed ...