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Download 4 - Theory of Plate Tectonics
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Theory of Plate Tectonics • Theory • Plate Boundaries – Convergent – Divergent – Transform • Hot Spots What is a SCIENTIFIC THEORY? A well tested concept that explains a wide range of observations • In 1965, J. Tuzo Wilson, a Canadian scientist proposed the theory of Plate Tectonics – Combined knowledge of sea-floor spreading with continental drift Theory of Plate Tectonics Late 1900’s Earth’s lithosphere is broken into sections called plates. Plates are always shifting and moving. Movement is driven by convection currents in the mantle. Evidence: All the evidence collected over the 1900’s was used in this theory. Crustal Plates Earth’ Layers Lithosphere Asthenosphere Earth Layers Convection Currents of Magma Plate Boundary Motion CONVERGE - Moving toward one another. connecting DIVERGE – Moving apart. dividing TRANSFORM – Sliding past one another. Plate Tectonics II Plates, Plate Boundaries, and Driving Forces http://www.visionlearning.com/library/module_viewer2.php?mid=66&l=&let1=Ear http://www.wwnorton.com/college/geo/egeo/flash/2_6.swf Plate Boundaries Convergent Boundary Oceanic Crust – Continental Crust Features Tectonic plates connecting •Subduction Zone Narrative and animation by: Monte Hieb and Nancy Hieb [email protected] •Trench •Volcanic Mountain Arc Converging Oceanic Continental Plates Mt. St. Helens, Washington Convergent Boundary Continental Crust – Continental Crust Tectonic plates connecting Features http://www.pbs.org/wgbh/aso/tryit/tectonics/ convergent.html •Folded Mountains Converging Continental Pates Himalayas Convergent Boundary Oceanic Crust – Oceanic Crust Features Tectonic plates connecting •Subduction Zone •Trench http://www.pbs.org/wgbh/aso/tryit/tectonics/ convergent.html •Island Arc Converging Oceanic Plates Subduction Zone Japan – island arc Divergent Boundary Tectonic plate dividing Narrative and animation by: Monte Hieb and Nancy Hieb [email protected] http://www.pbs.org/wgbh/aso/tryit/tectonics/ divergent.html Features •Mid-Ocean Ridge •Rift Zone Diverging Boundary Transform Boundary http://www.pbs.org/wgbh/aso/tryit/tectonics/transform.html http://www.wwnorton.com/college/geo/animations/transform_faulting.htm Plates move in opposite directions on either side of the transform boundary, causing earthquakes. Plates move in similar directions on either side of the fracture zone (red dashed line), resulting in fewer earthquakes. Transform Fault San Andreas Fault Magma has broken through crust as the plate moves over a spot Hot Spots http://www.wwnorton.com/college/geo/animations/hot_spot_volcanoes.htm http://www.classzone.com/books/earth_science/terc/content/inves tigations/es0810/es0810page03.cfm?chapter_no=investigation Additional Animations • http://www.seed.slb.com/flash/science/features/earth/livingplanet/plate_ boundaries/en/index.html?width=570&height=475&popup=true
