Unit 2 - Key Area 1 (Geosphere)
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Give an example of how the Earth generates internal heat
• Extra terrestrial impacts • Gravitational Contraction • Decay of Radioactive elements (fission)
Movement of heat from core to crust
Convection
Term when two plates move towards each other
Destructive boundary
A feature of a destructive boundary
• Subduction zones • Volcanoes • Extrusive rock • Intrusive rock • Metal deposits • Fold mountains • Earthquakes • Bauxite deposits
Formed when two land-based plates move towards each other
Collision zone
Formed when one land and one oceanic plate move towards each other
Subduction zone
Two plates diverging (moving away) from each other
Constructive boundary
Feature of constructive boundary
• Underwater volcanoes • Hydrothermal vents • Mineral deposits
Describe the formation of bauxite
• Rocks rich in aluminium are weathered • Aluminium leaches into soil and water • Occurs in tropical/warm areas • Layered in sedimentary rock
How is bauxite extracted
Open cast or strip mining
How is bauxite turned into aluminium metal?
Bauxite is purified to yield a white powder, aluminium oxide, from which aluminium can be extracted. The extraction is done by electrolysis.
Environmental issues with producing bauxite
• Heavy metal pollution in groundwater • High energy cost in electrolysis (fossil fuels) • Habitat degradation/loss
Describe the Earth’s geothermal gradient
The geothermal gradient is the amount that the Earth’s temperature increases with depth
Name two sources of geothermal energy
• Steam or hot water (underground) * Hot rocks (where water can be added)
How can geothermal energy be produced?
• steam or hot water can be extracted and used to generate electricity or piped directly to district heating schemes • ground source heat pumps (water pumped down and heated undergound) - turns a turbine on surface
Benefits of geothermal energy
Renewable Cheap to run once installed No Greehouse gases
Challenges of geothermal energy
Unavailable in certain countries that are not near a plate boundary/tectonic activity Toxic gases could potentially be released
Exstrusive rock
Rock formed on the surface of the Earth (outwith the crust)
Intrusive rock
Rock formed inside the earth
Magma
Molten rock stored in internal areas of the Earth
Lava
Molten rock that is on the surface of the Earth
Mineral
A substance made up of one type of compound or molcule (E.g. aluminium oxide)
Rock
Many types of minerals joined together chemically or due to pressure and compaction
Ore
a naturally occurring solid material from which a metal or valuable mineral can be extracted profitably