Plate Tectonics

Convection current 

current in Earth's mantle that transfers heat in Earth's interior and is the driving force for plate tectonics

Density 

the mass per unit volume of a substance under specified conditions of pressure and temperature

Crust 

outermost solid part of the earth

Mantle

the layer of the earth between the crust and the core

Outer core 

the upper zone of the earth's core

Oceanic plates 

a thick mass of igneous rock which lies under the ocean floor

Continental plates 

thick continental crust

Fossil 

a remnant or trace of an organism or a past geologic age

Pangea 

a hypothetical supercontinent that included all the landmasses of the earth before the Triassic Period

Theory of Tectonic Plates

describes the large scale motions of earth's lithosphere

Continental drift 

the movement, formation, or re-formation of continents described by the theory of plate tectonics

Convergent boundary 

tectonic plates collide with each other

Divergent boundary

tectonic plates are moving away from each other

Transform boundary

tectonic plates are not moving directly toward or directly away from each other but rather two tectonic plates grind past each other in a horizontal direction

Inner core 

the central part of the earth's core