restless Earth

restless Earth

1. Structure of the world

   • Inner core= solid Iron + Nickel. 15,000 degrees
     • Outer core= liquid layer Nickel + Iron
       • Mantle= semi molten rock. 4000 degrees. The thickest layer- makes up half the earth- about 2900 Km thick
         • crust= solid, made up of plates- thinnest layer- about 20 Km

2. Continental drift

   • Evidence
     • Plates fit together. Africa+ south America
     • Matching fossils different continents
   • Wegener
   • Pangaea
     • Continents were joined together
   • Explanation
     • molten rock heated by earths core
       • rises towards crust
         • cools sinks back down again
           • process= convection current
     • plates floating on mantle
     • convection currents in liquid mantle
       • Drag floating plates as they circulate

3. Plate boundaries

   • constructive
     • Formations
       • shield volcanoe
       • Earthquakes
     • 2 plates move apart. magma fills the gap
   • conservative
     • formations
       • Earthquake
     • plates scrape past each other travelling opposite directions/same direction different speeds
   • Destructive
     • oceanic +continental plate collide. Oceanic plate sub ducted under continental plate
     • formations
       • composite volcanoes
       • ocean trenches
       • earthquakes

4. types of plate

   • Oceanic
     • Heavy
     • Less thick
     • dense
   • Continental
     • thicker
     • light not dense

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