Evidence for Continental Drift

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  • Created by: Megan
  • Created on: 29-04-14 17:20

Continental Fit

...Wegener's Theory that all tha continents were once joined together in one large supercontinent called Pangea

  • South America and Africca's coastlines also fit almost perfectly together - Asia slots into the south east coast. 
  • Austrlia and Africa also fit into Antarctice, though this is not as accurate, probably because of the erosion of coaslines
  • North America's coastline well into the west coast of Eurasia

There are places where the edges overlap and where there are gaps but these are typically related to erosion or sedimentation due to continent divergence

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Sea Floor Spreading

...the formation of New Oceanic crust due to the spreading apart of two plates and magma rising up to fill the gap...

It takes place at mid-ocean ridges ie the mid-atlantic ridge and the newest crust is located at the centre of the ridge. Sea floor spreading could cause the red sea to expand in size until the African and Arabian continents are separated completely

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Paleomagnetism

  • During underwater volcani eruptions, basaltic lava is intruded into the crust and cools.
  • During cooling, individual minerals (ions) align themselves along the Earth's magnetic field - the direction of the magnetic pole reverses so this also reverses
  • These rocks are dated and rock of the same age and alignment would have been formed at the same time.
  • If this is either side of a divergent plate boundary, the rock was all formed in the same eruption. The farther apart the rocks, the further the continents have drifted apart.
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Biology, Climatology and Geology

...The remains of plants and animals on different plates..

The Glossopteris plant has been found across Africa, South America, Antarctica, India and Australia - seeds are unlikely to spread this far again indicating that the continents were once joined

Fossils of the mesosaurus  in both Africa and South America - the mesosaurus was a fresh water reptile around 50cm in length so could never have swum the Atlantic. This suggests the continents were once joined where the mesosaurusspread over what then separated into two continents

  • Evidence of coral reefs has been found in seas too cold for coral reefs
  • Coal, Sandstone, Limestone could not have formed in Britain with its present climate
  • Evidence of glaciation has been seen in Brazil and Central India
  • Coal formed under warm, wet conditions is being found beneath the Antarctic Ice

Geology - rocks of similar types, age, formation and structure occur in South East Brazil and South America....similarly, the Appalachian mountains of the Eastern USA correspond geologically with mountains in North West Europe

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