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Unit 6 & 7
Earth’s Layers and Plate Tectonics Notes
| Term | Definition |
|---|---|
| crust | the outermost solid layer of the earth. |
| mantle | The thickest of Earth’s layers, is located between the core and the crust. |
| Convection | the movement of matter that results from differences in density caused by variations in temperature. |
| lithosphere. | the outermost, rigid layer of Earth, which includes the crust and the upper mantle. |
| asthenosphere | a layer of weak or soft mantle that is made of rock that flows slowly. |
| mesosphere | the strong, lower part of the mantle. |
| outer core | the liquid layer of the Earth’s core. |
| inner core | the solid, dense center of our planet that extends from the bottom of the outer core to the center of Earth. |
| Plate tectonics | a theory that states that Earth’s outer layer, the lithosphere, is broken into large, slowly moving pieces called tectonic plates. |
| Convergent boundaries | form where two tectonic plates collide. |
| Divergent boundaries | where two tectonic plates move away from each other. |
| Transform boundaries | where two tectonic plates move past each other horizontally. |
| continental drift | says that the continents were once joined together, and, over time, they broke up and drifted apart. |
| Pangaea | about 200-300 million years ago, the continents were joined in a single large landmass. |
| Laurasia and Gondwana. | about 200 million years ago, a large rift formed, and Pangaea began to break into two continents |