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Description
Flashcards by Iona Diack, updated more than 1 year ago
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Created by Iona Diack
about 9 years ago
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| Question | Answer |
| What are the earths layers? | The core, The Mantle and The Crust. |
| What is the size of the crust? | It is very thin compared to the diameter of the earth |
| What state is the Mantle? | It behaves like a solid but is able to flow very slowly |
| What is the size of the core? | Half the radius of the earth. |
| What is a tectonic plate? | The earths crust and the upper part of the mantle that has been cracked into a number of large pieces. |
| What is the rate that the plates move? | Very slowly, around a few centimetres each year. |
| What was Alfred Wegener's Theory in 1915? | Continental drift |
| What did his theory suggest? | His idea was that the Earth's continents were once joined together, but gradually moved apart over millions of years. |
| What was the evidence that he used? | That the shapes of the coast of West Africa and South America look as thought they could fit together Or The fossils and rock structures in both places were similar. |
| What was the main reason that scientists found his theory so hard to believe? | Because he couldn't explain how the continents moved |
| How did the continents actually move? | Deep within the earth radioactive decay produces vast amounts of energy which heats up molten minerals in the mantle which expands. They become less dense and rise towards the surface and are then replaced by cooler material. These pushed the tectonic plates over the surface of the earth. |
| What is the thing called that pushed the tectonic plates over the surface of the Earth? | Convection currents |
| What happens at boundaries between tectonic plates? | Volcanic eruptions or Earthquakes. |
| Why can these events never be accurately predicted? | Because there are so many variables which do not show any consistent patterns |
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