Geography GCSE

Atmosphere: The layer of gases which make up the air around us

• Oxygen, needed for animals to breathe
• Carbon Dioxide for plant growth
• The greenhouse effect to keep the planet warm.

Hydrosphere: The layer of water-seas, rivers, lakes, groundwater and ice-on the Earth's crust.

• Water for animal and plant life
• Water cycle which moves water around the planet.

Biosphere: The very thin layer of living things on the crust.

• Plants and animals provide us with food
• Many living things can also be used to make medicines and as fuel.

Geosphere: The rocks of the Earth's crust, and deeper into the Earth towards the core.

• The Earth's core makes a magnetic field protecting us from space radiation
• We use rocks, minerals and fossil fuels as resources for fuel, building etc.

All we know about the Earth's interior comes from direct and indirect evidence.

• Direct evidence: from the Earth's surface

• Indirect evidence: earthquakes, material from space

+ the lithosphere: is the uppermost layer of the Earth. It is cool and brittle. It includes the very top of the mantle and above this the crust.

Lithosphere => tectonic plates (move on the astenosphere: partly molten partly solid, top of the mantle)

• Continental crust: forms the land, granite (low density igneous rock), 30-50 km thick
• Oceanic crust: under oceans, 6-8 km thick, basalt ( denser igneous rock)

Earthquakes=> wavew tell us about the physical state of the Earth. They speed up, change direction when they meet a new layer.

Core is thought to be metal( nickel) because of METEORITES.