The evolution of the Earths atmosphere/ Fossil fuels

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1- The earths surface is so hot its molten 4.5/ 4.6 billion years ago, so it has no atmosphere.

2- Temperature slightly decreases, a thin crust forms on the earth and there is lots of volcanic activity spewing out lots of CO2 and methene gas and steam.

3- Temperature drops meaning steam condenses to form oceans.

4- Green plants evolve and start to photosynthesise. This massively decreases CO2 and increases 02 in our atmosphere. (2.7 billion years ago)

5- CO2 levels drop because CO2 dissolvesinto the oceans and CO2 gets 'locked up in sedimentry rocks and fossil fuels.

              1.7 billion years ago - carbon dioxide + water --> glucose and oxygen

6-The modern day atmosphere consists of 21% oxygen, 78% nitrogen and 1% of others ( mainly argon) with a tiny % of CO2.

Making fossil fuels

Coal- Millions of years ago the plants photosynthesised and stored the suns energy. Dead plants fell into swampy water and the mud stopped them rotting away. The mud piles up and squashes the plants. After millions of years the mud becomes rock and the plants become coal. To get the coal, miners dig down shafts and tunnels. There is probably enough coal for 300 more years.

Oil and gas- Tiny animals live in the sea. When they die, they fall into the mud and don't rot away. Over millions of years they are buried deeper by the mud and sand. The pressure changes the mud and sand into rock and the animals become oil and gas. The oil and gas are trapped below the rock. We can drill down to get it. The oil will last about 40 years.

Fuels are important because they keep us warm and on the move. Most of the fuels that we use today have been made from crude oil- fuels for cars warmth, homes and electricity.

Crude oil- Crude oil is an important souce of energy and chemicals. Crude oil is a dark smelly liquid that is a mixture of many different hydrocarbon compounds-compounds that are made mainly of the elements carbon…

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