| A | B |
|---|
| Wegner'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 | Continental drift |
| Large ancient landmass that was composed of all the continents joined together | Pangaea |
| Hess's theory that new seafloor is formed when magma is forced upward toward the surface at a mid-ocean ridge | Seafloor spreading |
| Theory that Earth's crust and upper mantle are broken into plates that float and move around on a plasticlike layer of the mantle | Plate tectonics |
| A large section of Earth's oceanic or continental crust and rigid upper mantle that moves around on the asthenosphere | Plate |
| Rigid layer of Earth about 100 km thick, made of the crust and a part of the upper mantle | Lithosphere |
| Plasticlike layer of Earth on which the lithospheric plates float and move around | Asthenosphere |
| Current in Earth's mantle that transfers heat in Earth's interior and is the driving force for plate tectonics | Convection current |
