Evidence of Continental Drift

• Locations of glacial deposits from Permo-Carboniferous period

  • Antarctica
  • South America
  • Africa
  • India
  • Australia
• If the continents hadn't moved, it would suggest an ice sheet extended all the way from the equator to the north pole, which is highly unlikely
• If the continents had moved and were reassembled near the south pole, the ice sheet would've been a much more reasonable size
• Striations


  Grooves left in the rock parallel to the direction in which the glacier travels
• The directions of striations provide evidence that South America, India, South Africa and Australia all experienced glaciation at the same time
• In the current positions of the continents, the striations all point to the glacier originating in different positions
• If the continents were aligned closer to the south pole, the striations could all point to one glacier that originated in the south pole
• Many similar fossils have been found on separate continents, which would suggest that they were once joined
• If the plates had not moved, it would suggest that these species would have evolved identically and independently on separate continents, which would be contradictory to Darwin's theory of evolution
• The presence of Mesosaurus fossils on either side of the Atlantic Ocean suggests the continents have moved, as the Mesosaurus can't survive in salt water and can't fly
• Sea floor spreading was discovered in 1962 by Harry Hess
• An ocean drilling programme in the 1960s showed that the oldest oceanic crust was found closer to the continents and that the youngest was found closer to the middle of the ocean
• This shows that tectonic plates are moving because of the difference in age of different parts of the oceanic crust
• Hess's theory of sea floor spreading


  Magma rises up through the lithosphere at divergent plate boundaries and as it cools it solidifies to create new oceanic crust
• Palaeomagnetism


  As magma rises and solidifies, the iron particles become aligned to the earth's current magnetic field
• Every 200,000 to 300,000 years the earth's magnetic field flips, causing the orientation of the iron particles to change</b>
• This results in there being 'stripes' of iron particles on either side of the plate boundary which are mirrored
• The coastlines in certain parts of the world appear to fit together like jigsaw pieces, e.g. the coasts of South America and Africa