the crust and the uppermost mantle (grouped together due to their brittle physical properties)

the "plastic" layer within the mantle

when rocks are not longer brittle and become hot enough to flow

the solid iron part of the core

the liquid iron part of the core

a theory that states that Earth's surface is made of rigid slabs of rock, or "plates," that move

where two tectonic plates meet

forms where two tectonic plates divide, or separate, from each other

forms where two tectonic plates slide past each other

forms where two tectonic plates collide, or push into, each other

a type of convergent plate boundary where the denser plate sinks below the other plate as they move towards each other

the scientist who proposed the theory of plate tectonics

the circulation of material in the asthenosphere caused by differences in temperatures and densities (hot rises, cool sinks)