Plate tectonics

Continental drift
1. Sea floor spreading
2. Evidence
  1. Matching rocks
  2. Jigsaw fit of continents
  3. Fossils matching
Ideas
1. Wegner
  1. no force to move continents
2. Hess
  1. Mid Atlantic ridge
  2. Sea floor spreading
Plate tectonics
1. Zone A
  1. wo rising convectional currents cause an upwelling of magma
    1. Separate the continents
    2. Makes sea floor spread
2. Zone B
  1. Two colliding convection currents make...
    1. Mountain ranges
    2. Deep sea trench
3. Refer to diagram
Page 152
1. A
  1. What is a tectonic plate?
    1. Tectonic plates are twelve huge slabs of rock that make up the Earth's crust
2. B
  1. Describe how tectonic plates are carried along.
    1. Tectonic plates are moved very slowly by the convection currents with the mantle
3. Plates move incredibly slowly-just a few centimetres a year, on the liquid magma. Global positioning satellites track their movement
4. The plates
  1. Pacific
  2. Eurasion
  3. African
  4. Indo-Australian
  5. South American
  6. North American
  7. Antarctic
5. Earthquakes
  1. Happen when tectonic plates suddenly move against each other.
  2. When plates are caught on each other friction and pressure builds up and at one sudden point the pressure is released causing an earthquake
    1. E.g. San Andreas fault
  3. Place the plates slip-Focus
  4. Undersea earthquakes-Tsunamis
6. How well can we predict...
  1. Volcanic Eruptions
    1. Scientists monitor active volcanoes closely to look for signs that an eruption may happen soon. But scientists are still never exactly sure when a volcano will erupt, or how severe the eruptions will be
  2. Earthquakes
    1. Scientists can never predict exactly when plates will suddenly slip . So people living on plate boundaries can expect an earthquake at any time.

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Plate tectonics

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