topic 1 plate tectonics

• limited sediment accumulation supporting TPT


  older oceanic crust gets destroyed and 'recycled' back into mantle. Newly formed younger crust would not have existed long enough for much sediment to accumulate as it takes place over time. Proves new crust is formed at divergent boundaries at mid ocean ridge, plates move and older crust destroyed
• age of rocks supporting TPT

  Rocks nearest to crest are youngest and progressively gets older the further it is. Continuous formation pushes older seafloor. Shows that new oceanic crust is created at divergent boundaries, moving laterally on both sides of the mid ocean ridge as seafloor spreading occurs
• evidence of magnetic striping

  stripes of rock on the seafloor with alternating magnetic properties
• magnetic properties

  • normal polarity
  • reversed polarity
• Normal polarity

  earth's magnetic north points to geographical north

  earth's magnetic south points to geographical south
• Reversed Polarity

  earth's magnetic north points to geographical south

  earth's magnetic south points to geographical north
• geographic north/south

  fixed point on earth
• magnetic north/south

  compass needle points to as it is the earth's magnetic pole
• Basalt rocks

  forms oceanic crust. it is iron rich and contain magnetic minerals
• When basalt erupts from center of mid oceanic ridge


  it cools and solidifies, magnetic field of minerals in lava point towards Earth's magnetic north
• evidence of magnetic striping supporting TPT

  iron-rich lava erupting from centre of ridge cools and solidifies to form new oceanic crust. the crust is pushed in both directions away from centre of the ridge. When earth's polarity reverses, rocks record reversals as they have iron-rich minerals. More lava moves away from mid oceanic ridge due to plates diverging, a symmetrical zebra like pattern is formed.
• Tectonic plate theory

  tectonic plates are constantly moving which result in formation of landforms and phenomena
• lithosphere consists of crust and uppermost mantle
• mantle is made up of asthenosphere and lower mantle
• core is made up of only core
• crust is the outermost layer of the earth which is solid and has the lowest temperature. it is the thinnest layer (6-70km).
• uppermost mantle and crust make up lithosphere. the are solid and divided into tectonic plates, continental and oceanic
• continental

  land mass
• oceanic

  seafloor, denser than continental
• asthenosphere is semi solid and the heat from the core causes rocks there to melt