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STRUCTURE OF THE EARTH

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mindmap for chemistry homework
tw04
Mind Map by tw04, updated more than 1 year ago
tw04
Created by tw04 over 6 years ago
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STRUCTURE OF THE EARTH
  1. STRUCTURE OF THE EARTH AND TECTONIC PLATES
    1. The lithosphere includes the crust and the upper part of the mantel.
      1. The slow movement of tectonic plates is caused by very powerful convection currents.
        1. It is cracked into a number of huge pieces called tectonic plates!
          1. These plates are moving at a speed of 1cm each year.
        2. The outer part of the earth is called the lithosphere.
        3. CONTINENTAL DRIFT
          1. Mountains, alongside other of the earths features, were thought to be formed by hot, young earth cooling at the crust started to shrink and wrinkle, much like that of an apple that is drying out and aging. However there is now a new theory of how mountains are formed.
            1. The new theory is that mountains have been created by rock that is being forced upwards due to the collision of tectonic plates. This theory however has been introduced quite recently and has only just been accepted.
            2. Alfred Wegener had many ideas on continental drift; his main evidence was that, like a jigsaw puzzle; the continents two continents, South America and Africa fitted together. As well as that they both have the same patterns of rock layers.
              1. Also the two coasts had the same type of plants and animal fossils, some of the fossils found were of animals that could only be found in these parts of the world and they were proven to be unable to swim or fly.
                1. Finally there was not a possibility for there to have been a piece of land connecting the two continents therefore they must have been joined together.
                  1. However this theory was too many peoples disbelief as Wegener had no explanation as to how the continents moved. Also although Wegener was a scientist he was not known as a geologist but as a meteorologist therefore his ideas were given less credit by geologists.
              2. As he was not a geologist his ideas were not accepted until later in life, when geologists did in fact discover that what Wegener said was correct, this then helped explain many other theories that have now been proven. These theories are closely linked to Wegener’s idea of continental drift.
                1. One of the ideas proven by continental drift is that rock on the ocean floor is younger than that on the continents as new rock has been formed due to magma coming from inside the earth causing the older rock to be pushed away.
                  1. Wegener’s idea was official accepted when there was a discovery of underwater mountains and volcanoes when the Atlantic Ocean floor was surveyed.
              3. THE ATMOSPHERE TODAY
                1. The atmosphere is a mixture of gasses that surround the earth.
                  1. Nitrogen and Oxygen make up 99% of the atmosphere. The other 1% are small amount of other gases, mainly argon.
                  2. Water vapour is also present in the air, the amount changes when weather and humidity differs
                    1. Therefore the value of water vapour is not included in the composition of air.
                    2. FRACTIONAL DISTILLATION
                      1. The gases in the air are separated by fractional distillation.
                        1. The air is cooled until it becomes a liquid at about -200 degrees centigrade. As it warms up again the separate substances boil at different temperatures and can be collected separately.
                      2. MELTING POINTS AND BOILING POINTS
                        1. Melting point is the temperature at which a substance changes from a solid to a liquid.
                          1. Boiling point is the temperature at which a substance changes from a liquid to a gas.
                        2. Carbon dioxide has reduced due to:
                          1. Plants/micro-organisms
                            1. Absorbs carbon dioxide in photosynthesis.
                              1. Dissolves in oceans.
                                1. Used to form the shells/skeletons of marine organisms.
                                  1. Locked up as limestone/carbonates.
                                    1. Locked up as fossil fuels.
                                    2. Oxygen has increased due to:
                                      1. Plants/bacteria.
                                        1. Releasing oxygen in photosynthesis.
                                        2. Nitrogen has increased due to:
                                          1. Ammonia reacted with oxygen.
                                            1. Bacteria/micro-organisms release nitrogen.
                                            2. Water vapour has decreased due to earth's temperature cooling as well as water vapour condensing and forming the oceans.
                                            3. EARTHQUAKES AND VOLCANOES
                                              1. Earthquakes and volcanoes occur at plate boundaries.
                                                1. Heat from radioactive processes in the core causes convection currents in the mantel which make the plates move
                                                  1. Plates normally move slowly but sudden release of strain energy causes earthquakes.
                                                  2. Scientists cannot accurately predict when earthquakes and volcanic eruptions will occur because they can't be certain:
                                                    1. What is happening under the crust.
                                                      1. Where the forces/pressure are building up.
                                                        1. We cannot measure the forces.
                                                          1. When the forces reach their limit.
                                                        2. LIFE ON EARTH
                                                          1. Scientists are unsure how life on earth started, however there are many theories to explain how.
                                                            1. On early earth energy from sun, volcanoes or lightening could have formed a "primordial soup": oceans filled with a dilute solution of complex organic molecules needed for life (amino acids).
                                                              1. The Miller-Urey experiment demonstrated that amino acids could be made from the interaction of hydrocarbons, ammonia and lightning.
                                                              2. Other theories suggest that life started in space and was brought to earth on comets, asteroids and some meteorites.
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