From Live Science:

Eternal Flame Falls is a waterfall in New York State that houses one of the world’s few natural “eternal” flames.

The waterfall is about 30 feet (9 meters) tall and consists of two tiers; one at the top measuring 8 feet (2.5 m) high and the other at the base making up the remaining height. The cascade flows over an outcrop of shale, a type of sedimentary rock made of compacted clay, silt, mud and organic matter.

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