The soft "plastic" layer of the mantle that lithospheric plates move or glide around on.

This dense layer of the is thought to be liquid, spinning, and the source of gravity on Earth.

Layer of hot, solid material between the crust and Earth's core

A process in which the denser portions of a planet will sink to the center; while less dense materials rise to the surface. Such a process tends to create a core, crust, and mantle.

A vibration (wave) that travels through Earth carrying the energy released during an earthquake.

The theory that pieces of Earth's lithosphere are in constant motion driven by convection currents in the mantle.

A region where one tectonic plate sinks down into the asthenosphere because one plate is more dense than the other.

A rigid (stiff) layer of Earth that is made up of the uppermost part of the mantle and the crust.