Plate tectonics:a theory explaining the structure of the earth's crust and many associated phenomena as resulting from the interaction of rigid lithosphere plates that move slowly over the underlying mantle
Continental Drift: the gradual movement of the continents across the earth's surface through geological time
Pangaea:a hypothetical continent including all the landmass of the earth prior to the Triassic period when it split into Laurasia and Gondwanaland.
Asthenosphere:the upper layer of the earth's mantle, below the lithosphere, in which there is relatively low resistance to plastic flow and convection is thought to occur.
LIthosphere:he rigid outer part of the earth, consisting of the crust and upper mantle.
Mid-Oceanic-Ridge: A long seismically submarine ridge system situated in the middle of an ocean
Rift valleys: Steep walls formed by the downward displacement of a block of earth's surface between nearly parallel faults or fault systems.
Subduction: The side ways and downward movement of the edge of a plate of the earth's crust into the mantle beneath