Continental Drift.
A continental is Wegener's hypothesis that all continents were once connected in a single, large landmass that broke apart about 200 million years ago and drifted slowly to their current positions.
Pangaea
A Pangaea is a large, ancient landmass that was composed of all the continents joined together.
Seafloor Spreading
Seafloor Spreading is Hess's theory that new seafloor is formed when magma is forced upward toward the surface at a mid-ocean ridge.
Plate Tectonics
Plate Tectonics is a theory that Earth's crust and upper mantle are broken into plates that float and move around on a plastic-like layer of the mantle.
Plate
A plate is a large section of Earth's oceanic or continental crust and rigid upper mantle that moves around on the asthenosphere.
Lithosphere
The Lithosphere is a rigid layer of Earth about 100 km thick, made of the crust and a part of the upper mantle.
Asthenosphere
The Asthenosphere is a plastic-like layer of Earth on which the lithospheric plates float and move around.
Convection Current
A Convection Current is a current on Earth's mantle that transfers heat in Earth's interior and is the driving force for plate tectonics.