Jai Mehta 11AY

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  1. Plates “float” or move very slowly (a few mm per year) on the molten material of the mantle. Convection currents in the mantle cause this movement.
  2. Plates meet at plate boundaries or margins.
  3. Plates that move apart are known as diverging and are constructive, as new features are formed e.g. submarine volcanoes in the Mid Atlantic plate margin.
  4. Plates that move towards each other are converging and destructive – Fold Mountains, earthquakes, and volcanoes are common.
  5. Plates which move sideways against each other are conservative margins – material isn’t gained or lost, volcanoes are rare and earthquakes are common e.g. San Andreas Fault.
  6. Pangaea was a single landmass; made up of all the present continents, believed to have existed between 300 and 200 million years ago the rest of the Earth was covered by the Panthalassa Ocean. Pangaea split into two landmasses Laurasia in the north and Gondwanaland in the south, which subsequently broke up into several continents. These then moved slowly to their present positions, due to plate tectonics.

Jai Mehta 11AY

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A Map Showing The Location Of The Worlds Plate Boundaries.

Jai Mehta 11AY

  1. Volcanoes can be found where Earthquakes are found, at plate margins/ boundaries. The map below shows a good example of this; you can see where the pacific plate meets surrounding plates and many volcanoes are found around the pacific plate.

A Map Showing The ‘Pacific Ring Of Fire’.

Jai Mehta 11AY

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Constructive or divergent boundaries are places where plates are coming apart. As shown in the drawing above, when Earth's surface layer (the lithosphere) is pulled apart, it breaks along faults and they tilt slightly outward from each other. As the plates separate along the boundary, the block between the faults cracks and drops down into the soft, plastic interior (the asthenosphere). The sinking of the block forms a central valley called a rift. Magma (liquid rock) seeps upward to fill the cracks. In this way, new crust is formed along the boundary. Earthquakes occur ...

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