Earth science 9th grade
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Created by:
blakbabyma9494 on February 12, 2009
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17 terms
Terms | Definitions |
|---|---|
 plates: | sections of Earth's litosphere that is composed of crust and upper mantle (continental and oceanic plates) |
| plate techtonics | theory that crust and upper mantle move on plastic like layer of the mantle. |
| lithosphere: | ocean crust, continental crust, rigid upper mantle (about 100 km thick) |
| *asthenosphere: | plastic-like layer beneath the lithosphere |
| outer core: | liquid, mostly iron |
| inner core: | solid, dense, mostly iron and some nickel |
| continental drift | hypothesis that continents moved slowly to their current locations (Alfred Wegener, 1912) |
| pangaea: | single large land mass made up of all continents connected that broke apart 200 million years ago |
| seafloor spreading: | theory that magma moving upward spreads seafloor apart at mid ocean |
| convection current: | cycle of heating, rising, cooling, sinking that makes plates move |
| subduction zone: | area where one plate sinks below another; most dense plate sinks |
| convergent boundaries: | area where two plates move towards each other |
| divergent boundaries: | area where two plates move away from eachother |
| PLATE BOUNDARY | zone where many volcanos & earthquakes occur |
| MID-OCEAN RIDGE | a diverging boundary marked by a rift valley |
| FAULT | a crack or break in Earth's crust |
| TERRANE | block of lithoshere moved thousands of kilometers and attached to the edge of a continent |
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