Write an account of the relationship between tectonic processes and global structures

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Write an account of the relationship between tectonic processes and global structures

   The earth is divided into 3 main layers; the core (subdivided into the inner and outer core), the Mantle (subdivided into the asthenosphere and lithosphere), and finally the crust. All three layers are important when examining the formation of global structures, and their relationship to tectonics.

   The Earths (outer) core consists of dense molten rock containing iron and nickel alloys. Hot spots around the core generate thermal convection currents in the mantle, causing hot magma to rise due to heat, and cool near the lithosphere, dropping back down to the asthenosphere forming a cyclic current. The crust can be thought of as floating on a denser material, the asthenosphere, and currents caused in the asthenosphere have the ability to move the crust, driving plates apart, as well as bringing them together. Again, this process is cyclic, as when the plates collide (converge), dense oceanic crust sub-ducts/submerges and is destroyed by the magma. However, as plates move apart (diverge) new oceanic crust is formed. Both convergent and divergent plate margins are vital, and the unique movements of both margins have resulted in the formation of global structures, including Ocean Ridges, Ocean trenches, Rift Valleys and Mountain ranges.

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   At divergent plate margins where plates move apart, 2 main global structures are formed. The type and nature of these structures are determined by the location of the divergent plates. Where plates move apart in oceanic areas, an ‘oceanic ridge’ is likely to be formed. This can be seen where the South American plate and African plates are moving apart. Magma has shot up through the crack created and solidified, to create the ‘mid-Atlantic ridge’. Oceanic ridges are the longest continuous global uplifted structure on the planet stretching up to 60,000 km, and in some parts rising up to ...

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