Restless earth

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  • Crust- thin, outer layer of the earth split into tectonic plates
  • mantle- the dense, almost solid layer between core and the crust
  • plate margin-boundary where two plates meet
  • Convection currents occur in the earths crust due to radioactive decay in the core giving off heat energy
  • OCEANIC CRUST- newer than continental=less than 200 mill years, denser, can be renwed and destroyed
  • CONTINENTAL CRUST- older than oceanic=over 1500 mill years, less dense, cannot sink
  • DESTRUCTIVE PLATE MARGIN- when the denser oceanic crust subducts below the continental crust, great pressure occurs as the plates stick as they pass and the oceanc crust is destroyed to form magma----forms earthquakes, volcanoes and mountains
  • COLLISION PLATE MARGIN- when two continental plates meet and due to fricition between the plates as they try to go against eachother head on one another huge pressure is released when they buckle----forms earthquakes and mountains
  • CONSTRUCTIVE PLATE MARGIN- when two plates pull away from eachother leaving a gap between the plates where there is no solid crust,magma forces its way into the crack---forms volcanic land, volcanos and mountains normally under sea
  • CONSERVATIVE PLATE MARGIN- plates sliding past eachother at slightly different speeds and angles leads to them getting stuck, the build up of pressure causes one to slip---forms earthquakes
  • fold mountains- large mountain ranges where rock layers have been crumpled as theyre forced together
  • ocean trench- deep sections of the ocean usually in the subduction zone of a destructive plate margin
  • if Fold mountains and ocean trenchs are found together its a result of a destructive plate margin, if fold mountains are found alone its a result of a collision plate margin- the rivers run into a deeper section of the ocean and the sediment on the ocean floor is forced up by the two head on…

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