tectonic stuff

• continental drift theory


  the theory is that continents are moving away from each other (at a rate of 2.5 cm/year)

  It started as one mega-continent called Pangaea with one massive ocean called Tethys ocean - now there are 7 continents and 5 oceans

  the continents move because of tectonic plates shifting due to a change in currency of magma
• tectonic plates


  split the crust up to form tectonic plates these plates move in a variety of different directions creating tectonic hazards through friction and pressure

  eg - earthquakes, tsunami's, volcanic eruptions
• Iceland


  mid-Atlantic Ridge

  Eurasian to the right and North America to the left -> move in different directions (opposite) - constructive plates
• layer of the earth

  A) Inner core

  B) Outer core

  C) mantle

  D) crust

  
• Inner core


  hot as the surface of the sun

  70-2885 km thick

  around 5200'C

  made of metals, mainly iron and nickel

  solid
• outer core


  2391-5155 km thick

  4500-5000'C

  liquid
• mantle


  5000-6731 Km thick

  at least 1500'C

  hot molten rock called magma
• crust


  0-70 km thick

  0-30'C

  we live on

  made of oceanic (denser) and continental (lighter)
• convection current


  happens in the mantle

  when warm, liquid magma rises from the core to the crust, moves along the crust, cooling

  then the cool magma falls towards the core (gets heated up)

  continuous - causes tectonic plates to move
• convection current - diagram

  A) ridge

  B) trench

  C) lithosphere

  D) 700 km

  E) asthenosphere

  F) mantle

  G) slab pull

  
• plate boundary


  where two or more tectonic plates meet
• Destructive plates


  move together

  the denser oceanic plates gets subducted underneath the lighter continental plate

  continental - continental destructive plate boundaries crumple upwards forming mountains

  hazards - earthquakes, volcanic eruptions (when water seeps through the crust causes magma to form which rises through the lithosphere into magma chambers)
• destructive plate boundary diagram

  A) oceanic crust

  B) mantle

  C) continental crust

  
• constructive plate boundary


  plates move in opposite directions, away from each other

  lithosphere becomes thinner where plates move apart - leads to upwelling of mantle rock - this reduces pressure on the mantle and leads to melting of the mantle material which feeds magma chambers located under the sea - chains of underwater volcanos occur - creates islands

  hazards - volcanic eruptions and shields volcanos - gentle
• conservative plate boundaries


  plates slide past each other (not smoothly) at different speeds

  friction causes them to become stuck - pressure builds up overtime and when friction is overcome, it results in the plates slipping which releases energy and causes earthquakes

  San Andreas fault - California = massive earthquake

  hazards = earthquakes - destructive, have a hollow focus

  no volcanic eruptions
• constructive plate boundaries

  A) volcanic vent

  B) crust

  C) crust

  
• conservative plate boundaries