Plate Tectonics

Structure of the Earth
1. Core - Iron, Nickle, semi-molten outer core, 6,000C
2. Mantle - iron, magnesium, semi-molten, 5,000C
3. Asthenosphere - molten, convection currents occur
4. Crust - coolest, less dense rocks
  1. Oceanic - basaltic, 6-10km thick
    1. Continental - can be up to 70km, made from various rocks
5. Lithosphere - contains the rigid part of the mantle and the crust, 80-80km
Pangaea
1. Alfred Wegener published an idea that a supercontinent called Pangaea lived 300 million years ago
2. Split into two continents - Laurasia in the south and Gondwanaland in the north.
3. Evidence
  1. Geological - the fitting of south America and Africa, evidence of glaciation in India, Antarctica and south America., rock sequences in Scotland and Canada.
  2. Biological - fossil remains of Mesosaurus found in both southern America and southern Africa., plant remains in India and Antarctica
4. Palaeomagneticism - lava erupts from the Mid Atlantic Ridge, minerals in the lava are aligned with the Earth's magnetic pull. Sea floor spreading; older bands of rock are further away from the ridge.. The subduction zones equal out this increase in landmass.
Types of plate margins
1. Destructive
  1. Subduction Zone
  2. Less dense plate, subducts
    1. Oceanic<Continental
  3. Earthquakes and volcanoes
2. Constructive
  1. Two plates pulling apart
  2. Lava rises from the ridge and creates new land
3. Conservative
  1. Two plates slide past each other
  2. Friction is created, release causes earthquakes
  3. San Andreas Fault line
Tectonic Plate Landforms
1. Constructive
  1. Oceanic Ridge - where two plates pull apart there is a weaker zone in the crust and an increase in heat near the surface. the hotter expanded crust forms a ridge.
    1. Iceland - Mid Atlantic Ridge
  2. Rift Valley - the land mass fractures due to heat and rifts appart, central parts of land drop and form rift valleys.
2. Destructive
  1. Fold mountains - during subduction, one plate is melted and increased pressure then leads to volcanoes forming. Once the chamber is empty. The volcano becomes inactive and thus becomes a mountain.
  2. Island Arcs - a string of volcanic islands in the ocean along the plate boudary.

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Plate Tectonics

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	Created by Evie Davis over 7 years ago