Continental Drift

The gradual movement of the continents across the earth’s surface through geological

time.

Tectonic Plate

A block of lithosphere that consists of the crust and the rigid, outermost part of the

mantle.

Convergent Boundary

The boundary between tectonic plates that are colliding.

Divergent Boundary

The boundary between two tectonic plates that moving away from each other.

Transform Boundary

The boundary between tectonic plates that are sliding past each other horizontally.

Convection Currents

Any movement of matter that results from difference in density; may be vertical,

circular, or cyclical.

Subduction Zone

The zone where one lithospheric plate moves beneath another plate as a result of

tectonic forces.