Coal+-+Tom

Coal is formed by layer on top of layer of annual dead plants accumulating slowly that are protected from biodegration by normally acidic covering waters that are a natural antiseptic fighting microorganisms and then later deposits of mud protect against oxidisation in the large shallow seas — mainly during the Carboniferous period (about 360 million years ago) — trapping carbon in the ground in huge peat bogs that eventually get covered over and deeply buried by sediments under which they turn into coal. Coal mining has been around for a long time, it has been use since around 2000-3000 BC