Lecture 11 - • Volcanic eruptions • Earthquakes-Today,...

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Lecture 11 (9/13/10) Chapter 5 Composition of Rocks - The lithosphere is made up of rocks or material that was once composed of rock - Rocks are composed of minerals Inorganic solids that have a regular internal structure & composition - Minerals are composed of atoms and elements - More than one mineral type or form may be present in a rock - 3 basic rock types Igneous…ex: obsidian, granite Sedimentary…ex: conglomerate, sandstone Metamorphic… ex: quartzite, marble The Rock Cycle - The rock cycle is another example of a biogeochemical cycle - All three types of rock participate in the rock cycle - Figure 5-11 Plate Tectonics - The cycling of rocks is responsible for plate tectonics - Plate tectonics forms the unifying theory that explains more geological structures observed on the Earth’s surface - The theory of plate tectonics explains:
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Continental movement Mountain building
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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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Lecture 11 - • Volcanic eruptions • Earthquakes-Today,...

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