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Published byRudolf Cornelius Price Modified over 9 years ago
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Intermission: Intermission: Plate Tectonics
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National Oceanic and atmospheric Administration/National Geophysical Data Center
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Alfred Wegener
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Evidence: (1) Continents Fit Together
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Evidence: (2) Rocks & Structures Match Up
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Evidence: (3) Glacial Features
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Evidence: (4) Fossils
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Pangea
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Animation Link
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“If we are to believe Wegener’s Hypothesis, we must forget everything which has been learned in the last 70 years and start over again.” –Critic of Continental Drift in 1928
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Harry Hess
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Evidence: Seafloor
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Seafloor Spreading
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Seafloor Age
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Plate Tectonics
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Earth’s “surface” (lithosphere) is broken into plates Plates move on asthenosphere “Geology happens” where the plates interact with one another Basic Plate Tectonics
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What do we mean by the Outer Part of the Earth?
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Three Layers: Based on Composition LayerComposition CrustRock: Felsic & Mafic MantleRock: Ultramafic CoreMetal: Iron & Nickel
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Crustal Properties CrustDensityCompositionThicknessAge continental ~2.8 g/cm 3 Felsic Thick: 20-70 km Old: up to 4 Byrs oceanic ~3.2 g/cm 3 Mafic Thin: 2-10 km Young: <200 Mys
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Five Layers: Based on Physical Properties Layer“State” LithosphereSolid / Rigid AsthenospherePartly Liquid / “Plastic” Lower MantleSolid Outer CoreLiquid Inner CoreSolid
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Part #1 of Plate Tectonics Definition Earth’s “surface” is broken into rigid plates Surface = Lithosphere (includes Continental Lithosphere and Oceanic Lithosphere)
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Part #2 of Plate Tectonics Definition Plates move… …on the “plastic” Asthenosphere …at about 1-10 cm/yr
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Part #3 of Plate Tectonics Definition “Geology happens” where the plates interact with one another
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Earthquake Distribution
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Volcanoes and Plate Tectonics
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Part #3 of Plate Tectonics Definition “Geology happens” where the plates interact with one another How do they interact? 1.Pull Apart from one another (Diverge) (New rock is formed) 2.Push into one another (Converge) (Rock is destroyed) 3.Slide past one another (Rock is conserved)
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Divergent Boundary Results in the formation of Oceanic Crust
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Examples:
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Transform Boundary
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Transform Example
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San Andreas Fault
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Convergent Boundary: Subduction Results in the formation & growth of Continental Crust and destruction of Oceanic Crust Melting Produces More Felsic Magma
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Example: Pacific Northwest
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Example: Andes Mountains
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Convergent Boundary: Collision Results in the growth of Continental Crust
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1.Earth’s lithosphere is broken into 12-24 rigid plates 2.Plates move about 1-10 cm/yr on the plastic Asthenosphere 3.“Geology happens” where the plates interact with one another along Divergent, Transform, Subduction and Collisional Boundaries Basic Plate Tectonics - Revised
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What Drives Plate Tectonics? Internal Heat
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Convection Models
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Set the “Wayback Machine” to return to the Hadean… Return to Hadean ppt
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