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plate tectonics
science vocab.
| Term | Definition |
|---|---|
| continental drift | Wegener's idea that the continents slowly moved over time. |
| Pangaea | one big supercontinent |
| fossil | any trace of an ancient organism that has been preserved in rock. |
| mid-ocean ridge | mountain ranges in the middle of some ocean floors. |
| sea-floor spreading | when mid-ocean ridges continually add new material to the ocean floor. |
| deep-ocean trench | deep underwater canyons. |
| plates | when Earth's lithosphere is broken into pieces separated by cracks. |
| divergent boundary | plates move apart. |
| convergent boundary | plates come together |
| transform boundary | plates slip past each other |
| plate tectonics | plate motions in a single theory. |
| faults | breaks in Earth's crust where rocks have slipped past each other. |
| rift valley | a deep valley |