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Unformatted text preview: • Volcanic eruptions • Earthquakes-Today, the Earth’s lithosphere is divided into about 8 major tectonic plates & numerous smaller ones sometimes call microplates-Figure 5-3 Plate Movements-Most scientists believe that convection currents in Earth’s molten mantle cause plate movement-The plates move slowly: 8 to 30 cm (0.8 to 12 inches) a year-This movement has caused major changes in the position of the continents over the last few hundred million years-Figure 5-5 Continental Movements-Figure 5-4 Plate Boundaries-Earthquakes & volcanoes occur predominantly at plate boundaries-Three different types of boundaries • Convergent boundaries-“butting heads”…ex: oceanic plate boundaries/ Pacific versus Australian Plate • Divergent boundaries- “pulling apart”…Great Rift Valley in Africa • Transform fault (strike-slip)- “plates rubbing alongside each other...
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This document was uploaded on 02/01/2011.
- Spring '09