Coal as a source of energy and reasons why uses of coal has declined
Coal as a source of energy-A black or brown rock made of carbon.-Mud, sand and other materials are deposited over vegetative matter such as tree trunks and branches.-Deposited material prevents decomposition and also exerts pressure on it causing great heat.-Peat layers are formed which gradually change into coal.Usage of coal has declined due to:1. Discovery of other forms of energy such as petroleum.2. Exhaustion of old accessible mines.3. High cost of mining coal.