| A | B |
|---|
| Pangaea | single giant landmass that existed more than 200 million years ago and that gave rise to the present-day continents |
| midocean ridge | undersea mountain chain where new ocean floor is produced; a constructive (divergent) plate boundary |
| transform fault | fault that runs across a mid-ocean ridge |
| trench | a V-shaped valley on the ocean floor where old ocean floor is subducted; a destructive (convergent) plate boundary |
| subduction | process in which crust plunges back into the interior of the Earth |
| plate | in plate tectonics, one of the moving, irregularly shaped slabs that make up the Earth's lithosphere |
| tectonics | a branch of geology that deals with the movements that shape the Earth's crust |
| divergent boundary | a boundary at which plates move apart |
| convergent boundary | plate boundary at which plates come together |
| strike-slip boundary | a plate boundary at which two plates slip past each other horizontally |
