Spheres and their jobs
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.
Inside the Earth
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.