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objective 9
vocab
| Term | Definition |
|---|---|
| continental drift | hypotheses that continenets are in constant motion |
| mantle | middle layer of earth situated between the crust above the core below |
| Pangaea | ancient supercontinent composed of land that forms todays continents |
| mid ocean ridge | mountain range located on the seafloor in the middle of the ocean |
| seafloor spreading | new oceanic crust forms at a mid ocean ridge as old oceanic crust moves away |
| convection | circulation of material caused by ddifferces in temperature and density |
| convergent plate boundary | where two plates collide |
| divergent plate boundary | where two plates serperate |
| lithosphere | cold ridged outer most rock layer of earth |
| plate tectonics | theory of earths surface is made of rock plates that move away from the ridge |
| Subduction | sinking of a denser plate below a more buoyant plate at a convergent plate boundary |
| transform plate boundary | where two plates slide by each other |