| A | B |
|---|
| Continental Drift | The hypothesis that the continents slowly move across Earth's surface |
| Pangaea | The name of the single landmass that began to break apart 200 million years ago and gave rise to today's continents |
| Fossil | The preserved remains or traces of an organism that lived in the past |
| Mid-ocean Ridge | An undersea mountain chain where new ocean floor is produced; a divergent plate boundary under the ocean |
| Sea-floor Spreading | The process by which molten material adds new oceanic crust to the ocean floor |
| Deep-ocean Trench | A deep valley along the ocean floor beneath which oceanic crust slowly sinks toward the mantle |
| Subduction | The process by which oceanic crust sinks beneath deepocean trench and back into the mantle at a convergent plate boundary |
| Plate | A section of the lithosphere that slowly moves over the asthenosphere, carrying pieces of continental and oceanic crust |
| Divergent Boundary | A e boundary where two plates move away from each other |
| Convergent Boundary | A plate boundary where two plates move towards each other |
| Transform Boundary | A late boundary where two plates move past each other in oposite directions |
| Plate Tectonics | The theory that pieces of Earth's lithosphere are in constant motion, driven by convection currents in the mantle |
| Fault | A break in Earth's crust along which rocks move |
| Rift Valley | A deep valley that forms when two plates move apart |
