How coal was made
In Britain, coal was formed at various times between 170 million to 300 million years ago.
Coal began as ancient forests and vegetation which became buried and compressed by earth, rock and lava over long periods of time. The rotting vegetation was eventually composted, condensed and compressed, under extreme pressure, which formed coal.
These layers of compacted ancient forest have now formed coal seams as deep as 800 metres which run for hundreds of miles across Britain.
Currently, the largest coal seam we are mining is 7 metres thick and lies 750 meters under Warwickshire.