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

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Introduction

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) ...read more.

Middle

These volcanoes are fairly gentle due to the volatile nature of the lava. As the ridge widens (10-90+mm/year) new basaltic oceanic crust is formed and spreads outward, however faults form and the variety of movement along the oceanic ridge has inevitably led to earthquakes. Divergent plate margins in continental areas such as Africa, have a different feature associated with them. As the crust move away from each other, the brittle and thin parts of the crust on the sides of the 'scarps' fall away, landing in between the parallel faults. Over time, this debris builds up and leads to the formation of a rift valley as seen in Africa. The largest rift valley is the African rift valley, which stretches 4000 km from Mozambique all the way to the red sea. From the red sea it carries on further north into Jordon, measuring a total distance of 5,500 km. Identified by the characteristic series of step faults, scarps on the sides of the valley are steep and inward facing and can measure up to 600 m above the valley floor. ...read more.

Conclusion

American boundary, and are a direct result of the deformation of sediment on the continental shelf. Both earthquake and volcanic activity are present at varying levels of intensity. The tremors are caused by the continual pressure built up by the friction between oceanic and continental crust, with increasing pressure leading to more violent tremors. Volcanic activity is also rife in these areas, due to the increasing amount of magma being produced in the crust, leading to a build up of pressure in the lithosphere, which then breaks through onto the surface leading to violent eruptions. This process is similar when two oceanic plates collide, forcing one to subduct, and the other to remain on the surface. This also leads to the creation of trenches and mountain ranges, as well as tectonic activity. When two continental plates collide, sediments and fluvial deposits between the two plates are compressed and deformed as the plates come together, and are forced upwards into Fold Mountains. This is evident throughout the world and has led to the formation of the world's most famous structures such as the Himalayas, and the Alps. ...read more.

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