Deep in the woods of western New York, a small golden flame burns inside a grotto hidden behind a rushing waterfall. It looks like a magic trick, but it is real, fragile, and kept alive by hikers who reignite it with pocket lighters. The real mystery, though, lies 1,300 feet below the surface.

This episode journeys into the Shale Creek Preserve at Chestnut Ridge Park to explore Eternal Flame Falls, where a natural gas seep produces a flame that scientists say should not exist. We unpack the double-edged sword of viral fame, the ecological battle to save a trampled ravine, and a geological puzzle that suggests the Earth is manufacturing complex natural gas in a way our textbooks call impossible. It matters because this muddy ravine may hold the key to an entirely unknown chemical process.

• The flame is a natural gas seep that can b ...