plate movement
- 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
- Inner core
- 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
- Earth structure
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