The Story of Coal 

Welcome to over 360 million years ago!

There were no birds but giant dragonflies ruled the air! There were no mammals but lizard-like creatures lived on the land

The plants were very different too. No oak trees or fruit trees or flowers at all, but vast numbers of tree ferns growing in enormous swamps

As the tree ferns died, they fell into the swamps. Without air their carbon could not rot away into carbon dioxide. Instead the trunks and leaves and roots crumbled into little bits and pieces and became a pile of soggy remains (peat)... yet at thousands of feet deep, this was a really massive pile!

Over millions of years the landscape changed. The swamps dried out and the peat was covered by rock from volcanoes and silt from new rivers. The peat became squashed by the weight of the rock above it. Sea levels rose, and sometimes the peat lay under the sea and was squashed even more by the weight of hundreds of metres of water above it.

Over millions of years, as the Earth's crust (its top layer) got pushed around by volcanoes, our layer of ancient peat was pushed into layers of rock which were super hot. The peat was 'cooked' at a very high temperature and pressure and it changed into black coal.

Millions of years later, humans find these deep coal beds which are the remains of the fossilised swamp plants. The coal is dug out and burnt to provide energy for power stations and to heat homes. However, all the carbon which had been locked away in the rocks of the Earth, is now released as carbon dioxide. Carbon dioxide is a greenhouse gas and it helps to warm the surface of the Earth. The more carbon dioxide there is in the World's atmosphere, the warmer the World will become.   

How do we know that coal is 'fossilised swamp plants'?
See to see bits of tree in coal under a microscope!