plate movement

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  • Created by: Sharon
  • Created on: 18-12-15 14:22
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  • Plate movement
    • Earth structure
      • Inner core
        • centre,hottest,solid iron and nickel 5,500oc, 6371-5100km
      • outter core
        • layer surrounding inner, liquid layer-iron & nickel, 5100-2900km
      • mantle
        • widest section 2,900km thick, semi-molten rock "magma"
      • crust
        • outter later, 0-60km thick, solid rock
        • Asthenosphere - underlying later, ability to flow, temperature high for crystals to melt.
        • lithosphere - nearer surface, revents melting, cannot flow, brittle so broken into plates
    • The movement of the plates and the activity inside the earth is called plate tectonics
    • Continental drift.
      • Alfred Wegener-Pangea, split and caused continents today.
      • Fit of continents. jigsaw of SA and Africa,
      • Rock types, rocks on two continents with same mineral content and age
      • Mountain chains, Precambrian fold mountain chain stretches SA to africa and back.
      • Fossils, such animals couldn't cross oceans.
      • Palaeomagnetism, iron rich minerals record movement of magnetic field of earth. polar wandering cure shows movement continents.
      • Glaciation, both Sa and africa deposits of fine grain mix deposited by ice thus must've been near poles
    • Sea Floor Spreading - plates moved by convection currents due to radioactive decay
      • Mid ocean ridges, plates move apart magma bursts through can create islands-iceland
      • high heat flow and volcanic activity with gravity anomaly, bascially magma closer to surface due to convection currents.
      • Transform faults and earthquakes plates moving opposite direction.
      • width of oceans, satelites record fixed recievers two halves of iceland move away at 2.5cm pa
      • magnetic anomalies magnetic field undergoes reversal 4 x per mil years, result striped pattern
      • dating sediments - fine grained sediments dates using pelagic microfossils
      • thickness of sediment from MOR


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