Explain why tectonic processes produce a variety of contrasting landscapes 70 marks

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“Explain why tectonic processes produce a variety of contrasting landscapes.”

70 marks

PLAN:

  • Wegener’s theory of plate tectonics
  • Pangea and how the earths landscape has changed globally
  • Features of oceanic plates: abyssal planes; mid ocean ridge – mountain ranges/islands; sea mounts – volcanic hotspot chains
  • Features at boundaries: ocean  trenches at subduction zones; fold mountains; volcanos – volcanic island arcs; faults – San Andrea’s
  • Features of continental crust: folding of curst; Folding and faulting
  • Intrusions – tors/batholiths/dykes/sills (due to erosion/ weathering) – not by tectonics!
  • Flood basalts

In my report I am going to discuss how the seven major tectonic plates move around the earth and produce the different structures found at the surface of the planet, and have resulted in varying land formations over the earth’s history. To do this I am going to use a variety of case studies to support the theories of formation and provide evidence for my argument.

My case studies are as follows:

  • Mid Atlantic ridge/ Iceland
  • Hawaiian emperor seamount range
  • pacific abyssal plane
  • Marinas trench
  • Himalayas
  • Japan
  • San Andrea’s fault
  • Cyprus
  • Whin sill
  • Dartmoor tors
  • Siberian traps

As well as evidence of how tectonic activity has shaped the landscape I will also be looking at external factors which have affected the landscape of the planet. I have structured y report into several sub sections:

  • The theory of plate tectonics
  • Oceanic landforms
  • Continental landforms
  • External igneous land formations
  • Conclusion

The theory of plate tectonics; a global scale

The theory of continental drift was first introduced by Alfred Wegener in 1915 which was proposed to explain the geometric and geological similarities between continents now separated by oceans. The countries of South America, Africa, India and Antarctica were seen to fit together to form a supercontinent known as Gondwana and North America and Eurasia fitted together into a second supercontinent Laurasia. These two supercontinents appeared to be joined together in Central America to for one continuous landmass called Pangea, which enclosed the Tethys Ocean (moving continents and making mountains – introducing geology; Graham Park 2006). The now accepted theory about plate tectonics moving due to convection currents in the mantle has changed the landscape of the planet on a global scale by moving continents over millions of years to produce a variety of different continental land formations. It has been suggested by geologists that the earth’s continents have parted and come together 6 times in the earth and will likely come together in the future. One supercontinent cycle is estimated to take 300 to 500 million years; we are currently 160 million years into the next cycle (Burbank and Anderson, 2001) and because of these tectonic processes have not only caused changes to the landscape on national scales, but on a global scale as well.

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Oceanic landforms

The earth’s landscape varies extensively around the planet. Abyssal plains cover the majority of the ocean floor at depths of 6,500 feet below sea level and are the most featureless landscape on the planet. They are formed when new ocean crust is produced by sea floor spreading; the new crust gradually gets overlain with sediment which eventually produces vast flat areas of sea floor, they can extend for thousands of kilometres and 1000km2 only tend to vary in slope gradient by less than one foot(The Blue Planet BBC, 2005). The largest example of an abyssal plane is the ocean ...

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