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Published byGregory Allen Modified over 8 years ago
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Plate Tectonic Theory Theory of Plate Tectonics -Earth’s crust is broken into plates which float and move.
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Earth’s crust made of many plates is similar to the shapes on a outside of a soccer ball.
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There are about 13 plates covering Earth’s surface
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Two Types of Plates Continental Plates – lighter, thicker, made of granite Oceanic Plates – heavier, thinner, made of basalt
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Plate Boundaries (edges) When the plates move, their boundaries, or edges, can scrape each other or collide.
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Convergent Boundary Plates move toward each other
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Convergent Boundary When two continental plates move into each other, the plates combine and form mountains. (India into Asia) http://www.classzone.com/books/earth_science/terc/content/visualizations/es1105/es1105page01.cfm?chapter_no=visualization http://www.absorblearning.c om/media/attachment.action ?quick=12t&att=2783
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Convergent Boundary When an oceanic plate runs into a continental plate, the heavier oceanic plate subducts (sinks) into the mantle and melts back into magma.
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Volcanic mountains and deep sea trenches are created along this edge. http://www. absorblearn ing.com/me dia/attachm ent.action? quick=12s &att=2781
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Oceanic plate into continental Example: Pacific plate (oceanic) subducts (sinks) under Japan (continental). http://maps.google.com/ http://maps.google.com/
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Divergent Boundary Plates move apart
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When both diverging plates are oceanic, it is called seafloor spreading (Mid-Atlantic Ridge)
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When both diverging plates are continental it is called rift valley formation (Africa) http://highered.mcgraw- hill.com/olcweb/cgi/pluginpop.cgi?it=swf::640::480::/sites/dl/free/0072402466/30425/19_21.swf::Fig.%2019.21% 20-%20Evolution%20of%20a%20Divergent%20Plate%20Boundary
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Transform Boundary Plates slide past each other
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San Andreas Fault
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San Andreas Fault, CA Each time the plates slide past each other, an earthquake occurs
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Find the three boundaries http://www.pbs.org/wgbh/aso/tryit/tectonics/shockwave.html
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Asthenosphere A plastic-like layer found below the lithosphere. The rigid oceanic and continental plates of the lithosphere sit on top
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The Asthenosphere is heated by the hot Outer Core
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Convection Current Hot material rises, cooler material sinks, creating a current, called a Convection Current core mantle crust
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When the asthenosphere moves, it carries the lithospheric plates Convection currents cause plate motion http://www.absorblearning.com/media/attachment.action?quick=12p&att=2775 https://www.youtube.com/watch?v=ryrXAGY1dmE
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Every time these plates move we get earthquakes, volcanic eruptions, and possibly tsunamis
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