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Plate Tectonics

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In This Chapter: Composition of the Earth Layers of the Earth: crust, outer core, inner core, mantle Continental Drift Theory Evidence: fossil clues, climate clues, rock clues Pangaea Theory of Seafloor Spreading Evidence: rock and magnetic clues Plate Tectonics Plate movements Plate boundaries Convection currents

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Fossil Rock Anthem http://www.youtube.com/watch?v=ClJ5lwl_wM0

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Continental Drift Theory Proposed by Alfred Wegner Continents were at one time all joined together (Pangaea)

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Pangaea http://3dparks.wr.usgs.gov/nyc/images/fig83.jpg

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Clues to Pangaea Fossil Clues Reptile Mesosaurus Fern Glossopteris http://www.fossilmall.com/EDCOPE_Enterprises/plants/plfossil29/GLOSSOPTERIS-L.jpg http://www.greatsouth.net/fossil_replicas/images_fossil_replicas/frp100.jpg

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Clues to Pangaea Climate Clues Fossils of warm water plants found on Arctic Ocean island (Glossopteris) Glacial deposits & grooved bedrock in South America, Africa, India, and Australia These areas were once connected http://upload.wikimedia.org/wikipedia/commons/thumb/6/67/Pangaea_Glossopteris.jpg/220p x-Pangaea_Glossopteris.jpg

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Clues to Pangaea Rock Clues Similar rock structures are found on different continents Ex. Appalachian Mountains: Eastern U.S. Greenland Western Europe http://www.jamestown-ri.info/Pangaea_mts.jpg

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How Do The Continents Drift? Theory of Seafloor Spreading supports Wegeners theory http://mail.colonial.net/~hkaiter/Aaa_web_images2012/sfsseafloor_spreading.gif

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Theory of Seafloor Spreading Proposed by Harry Hess in 1960s Hot, less dense material in mantle is forced upward to surface at Mid Ocean Ridge It cools, contracts, turns, and flows sideways, carrying the seafloor away from the ridge in both directions MAGMA! Moves upward, flows into cracks, solidifies to form new seafloor

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Evidence of Seafloor Spreading Age difference in rocks Glomar Challenger (research ship) found youngest rocks are near center of ridges Magnetic clues Magnetic field has reversed itself http://www.gcsescience.com/Magnetic-Reversal-Mid-Ocean-Ridge.gif

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Plate Tectonics Plate movements The Earths crust and upper mantle are broken into sections called plates http://www.enchantedlearning.com/egifs/Earthsplates.GIF

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Earths Composition Lithosphere Upper mantle and crust Rigid, less dense than material below it; divided into plates Floats on asthenosphere Asthenosphere Located below lithosphere More dense, plastic-like

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http://www.physicalgeography.net/fundamentals/images/lithosphere.gif

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Plate Boundaries Divergent Boundary (divide) Plates move away from each other http://geographicalconcepts.wikispaces.com/file/view/db.jpg/177810579/db.jpg

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Plate Boundaries Convergent Boundary One fault surface is forced up and over the other fault surface Forms mountains & subduction zones http://www.geo.cornell.edu/hawaii/220/PRI/images/subduction2.jpg

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Plate Boundaries Transform Boundary Plates slide past each other Not much upward/downward movement http://www.divediscover.whoi.edu/images/tectonics-slide.jpg

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Causes of Plate Tectonics http://rockdale.k12.ga.us/schools/dms/class/jtamburro/Class%20Documents/Geology%20Unit/Convection%20current.JPG

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Effects of Plate Tectonics Volcanoes Earthquakes Mountain building Ocean rift formation Tsunamis Ocean basins

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Review What are the 3 types of clues for Pangaea? Who proposed the Continental Drift Theory? What theory did Harry Hess propose? What is the difference between the lithosphere and asthenosphere?

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References Glencoe McGraw-Hill,. Earth Science. 2007. Print. http://geographicalconcepts.wikispaces.com/file/view/db.jpg/177810579/db.jpg http://mail.colonial.net/~hkaiter/Aaa_web_images2012/sfsseafloor_spreading.gif http://rockdale.k12.ga.us/schools/dms/class/jtamburro/Class%20Documents/Geology%20Unit/Convection%20current.JPG http://upload.wikimedia.org/wikipedia/commons/thumb/6/67/Pangaea_Glossopteris.jpg/220px-Pangaea_Glossopteris.jpg http://3dparks.wr.usgs.gov/nyc/images/fig83.jpg http://www.divediscover.whoi.edu/images/tectonics-slide.jpg http://www.enchantedlearning.com/egifs/Earthsplates.GIF http://www.fossilmall.com/EDCOPE_Enterprises/plants/plfossil29/GLOSSOPTERIS-L.jpg http://www.gcsescience.com/Magnetic-Reversal-Mid-Ocean-Ridge.gif http://www.geo.cornell.edu/hawaii/220/PRI/images/subduction2.jpg http://www.greatsouth.net/fossil_replicas/images_fossil_replicas/frp100.jpg http://www.jamestown-ri.info/Pangaea_mts.jpg http://www.physicalgeography.net/fundamentals/images/lithosphere.gif http://www.youtube.com/watch?v=ClJ5lwl_wM0