A knowledge of plate tectonics does not just help in understanding many geographical processes and features but also in managing them. How far do you agree with this view?

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Sophie Curtis                                                                                 Essay assignment no1

A2 Geography Essay

A knowledge of plate tectonics does not just help in understanding many geographical processes and features but also in managing them. How far do you agree with this view?

Plate tectonics helps us to understand three main things; the distribution of the worlds major landforms, where natural hazards such as volcanoes and earthquakes can strike, and the distribution of minerals and energy supplies.

   There are at seven main plates composed of the narrow crust that forms the outer shell or limosphere of the Earth. All of these plates are in continuous motion moving in different directions.  This is continental drift and can be proven by fossil evidence, structure of continents and climatic change. This causes to plates to meet.

 Plate margins are the points at which the plates meet. There are three different types of these, each formed by a different process and each causing a different feature.

The Constructive plate margin is located where two plates are moving apart.  As they separate magma rises into the gap formed and creates new land. One example of this is the mid – Atlantic ridge which was formed as the American plate and the Eurasian plate moved away from each other, pulled by diverging convection currents in the upper mantle. As the plates move apart, faults form and the fractures are widened by tension.  Magma is forced up these fissures by convection currents and reaches the surface as lava. The volcanoes that are found on constructive boundaries are shield volcanoes, for example, Mauna Loa in Hawaii. The magma is derived from the planet's mantle and is quite free flowing. The lava formed from this magma, usually basalt, and flows for some distance over the surface before it sets, this gives the volcano a slightly sloped shape, there is also less pyroclastic material (ash, lava bombs etc). The lava of a shield volcano is not ejected violently but simply flows over the crater rim. Mauna Loa has been active for over 150 years, erupting on average every three years are a major tourist attraction.

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Where continental plates drift apart, the major landform created is a rift valley, for example that in East Africa. The doming up of the crust, as a result of the intense pressure from the convection currents within the mantle, leads to rocks splitting at their weakest point. Rift valleys occur where two parallel down- faults have produced a trough. The East African rift valley, beginning at river Jordan, stretches for over 4,000km.  It is situated where the Arabian plate has separated from the African plate. Volcanoes are associated with the eastern rift, for example in Kenya and Tanzania, as the ...

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