Naturally-occurring fire from a vent in the ground at Yanartas, Turkey. This site contains dozens of such fires. The flames are fueled by natural gas emissions from underlying rocks, which contain kerogens (organic deposits) and serpentine. These release a mixture of gases containing mostly methane with some hydrogen from the serpentinisation of rocks, with no involvement from microorganisms. The fires have been burning for at least 2500 years, and were recorded in classical texts. These vents represent the biggest emission of abiogenic methane discovered on land.