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Lessons 1-3
| Term | Definition |
|---|---|
| Continental drift | The hypothesis that the continents slowly move across the Earth's surface. |
| Pangaea | The name of a 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 a organism that lived in the past. |
| Mid-ocean ridge | An undersea mountain chain where new ocean floor is produced;a divergent plate boundary. |
| 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 but which oceanic crust sinks beneath a deep-ocean trench and back into the mantle at 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 plate boundary where two plates move away from each other. |
| Convergent boundary | A plate boundary where two plates move toward each other. |
| Transform boundary | A plate boundary where two plates move past each other in opposite directions. |
| Plate tectonics | The theory that pieces of the 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. |