AQA A2 Geography Plate Tectonics: Structure of the Earth Key Words

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  • Created on: 22-08-13 20:32
Preview of AQA A2 Geography Plate Tectonics: Structure of the Earth Key Words

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Word Definition
Inner core Innermost part of the earth
Made up of iron and nickel
Temperatures reach 6,000°
Outer core Semi-molten
Contains iron and nickel
Mantle Largely composed of silicate rocks rich in iron and magnesium
Most of mantle is semi-molten
Temperatures near core reach 5,000°
Crust Thinnest layer which has the coolest, least dense rocks
Made up of oceanic and continental crust
Tectonic plate The lithosphere is divided into slabs called tectonic plates that
move due to convection currents in the asthenosphere
Oceanic crust Mainly basalt in nature
7-10 km thick
Continental crust Composed of igneous, sedimentary and metamorphic rock
Can be as much as 70 km thick
Asthenosphere Layer made up of most of the mantle
Least rigid
Convection currents are generated here
Lithosphere Made up of the crust and rigid upper mantle
Sial Rocks made up of silicon and aluminium
Found in continental crust
Sima Rocks made up of silicon and magnesium
Found in oceanic crust
Mohorovijic discontinuity Boundary between the crust and the mantle
Plate boundary The place where plates meet
Convection currents Circular movements of magma in the asthenosphere


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