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Download The Theory of Plate Tectonics
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The Theory of Plate Tectonics Plate Tectonics • Became a theory in the 1960’s • Describes plate movements AND explains why they move Plate Tectonics • Two types of crust: Oceanic and Continental • Plates are usually made of both types • Plates: Chunks of lithosphere “floating” around on the asthenosphere • Earthquake data and volcanoes are used to find the boundaries of the plate boundaries. Plate Boundaries • Three Types: • Divergent Boundaries: plate are moving away from each other • Plates move apart, molten rock from asthenosphere fills gap Plate Boundaries • Most found on the ocean floor (mid-ocean ridges) • Rift valley: valley in the center of the midocean ridge Plate Boundaries • volcanoes and earthquakes occur at divergent plate boundaries divergent boundaries Where is this happening at? MidAtlantic Ridge East Pacific Rise • Iceland The Red Sea Divergent boundaries
