Coal and petroleum are formed as a result of degradation of ancient plant life which lived millions of years ago. These dead plant matter started to pile up, eventually forming a substance called peat. Over time, heat and pressure from geological processes transformed these materials into coal. Coal is found in the solid-state while petroleum is located in a liquid state. Coal is formed by mild reduction of land life, while a substantial decrease in aquatic life includes petroleum. Petroleum stores migrate to other locations based on environmental conditions coal stores can't.