Plate Tectonics: a theory of global tectonics in which the lithosphere is divided into a number of crustal plates, each of which moves on the plastic asthenosphere more or less independently to collide with, slide under, or move past adjacent plates.
Continental Drift: the lateral movement of continents resulting from the motion of crustal plates.
Pangaea: the hypothetical landmass that existed when all continents were joined, from about 300 to 200 million years ago.
Asthenosphere: the region below the lithosphere, variously estimated as being from fifty to several hundred miles thick, in which the rock is less rigid than that above and below but rigid enough to transmit transverse seismic waves.
Lithosphere: the solid portion of the earth or the crust and upper mantle of the earth.