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Plate Tectonics. Liz LaRosa for use with my 5 th Grade Science Class http://www.middleschoolscience.com 2009 . Earth’s Layers. 1.Scientists determined the inner layers using seismic waves.
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Plate Tectonics Liz LaRosa for use with my 5th Grade Science Class http://www.middleschoolscience.com 2009
Earth’s Layers 1.Scientists determined the inner layers using seismic waves. 2.Earth’s crust is broken up into huge tectonic plates (lithosphere) that drift atop the soft, putty-like underlying middle mantle (asthenosphere). The lithosphere is made up of crust and upper mantle.
The Mantle • Thickest layer • Contains most of the Earth’s mass • Is denser than the crust
Plate movement is caused by convection currents in the asthenosphere. http://pubs.usgs.gov/gip/dynamic/unanswered.html
The Core • Both inner and outer core are made of hot metals. • The inner core is solid. • The outer core is liquid.
Plates can move in three directions. • Together- Convergent boundary • Apart- Divergent boundary • Past each other-Transform boundary
Different Types of Boundaries http://pubs.usgs.gov/gip/dynamic/understanding.html
Continental-Continental collision ex: Indian and Eurasian Plates result in non- volcanic continental mountains-the Himalayan Mountains Eurasian Plate Indian Plate
Sea Floor Spreading • Mid Ocean Ridges – underwater mountain chains that run through the Earth’s Basins • Magma rises to the surface and solidifies and new crust forms • Older Crust is pushed farther away from the ridge
Divergent Boundary – Arabian and African Plates Arabian Plate Red Sea African Plate
Divergent Boundary – Iceland http://pubs.usgs.gov/gip/dynamic/understanding.html
Convergent Boundary – Oceanic & ContinentalThis is called a Subduction Zone because the ocean plate is sinking under the continental. Less dense granite Denser basalt http://pubs.usgs.gov/gip/dynamic/understanding.html & http://www.geology.com
At subduction zones of continental and oceanic crust there are many volcanoes( a volcanic arc) and trenches due to the more dense ocean plate sinking.
Transform Boundary – San Andreas FaultAt this boundary, crust is neither created or destroyed.Manyearthquakes occur at all plate boundaries. www.geology.com