A trail in Chestnut Ridge Park leads to a small waterfall with a contradiction tucked behind it. Inside a shallow grotto, close to the falling water, a flame can flicker from the rock. The fuel does not arrive through a hidden park pipe. Natural gas migrates through fractures in Devonian shale and emerges at the surface as a seep.

The site is called Eternal Flame Falls, but “eternal” is a nickname, not a guarantee that one continuous flame can never go out. The persistent geological feature is the gas supply. When that seep is burning, the protected recess behind the waterfall turns it into an arresting pairing of orange flame and moving water.

Researchers have studied the seep because its gas chemistry and geological setting complicate simple assumptions about how natural gas forms and travels through shale. For a visitor, the visible lesson is smaller and immediate: rock can behave like plumbing when cracks give buried gas a route upward. The waterfall did not create the fuel, and the flame is not supernatural. Water eroded a grotto into the creek bed; fractured rock delivered gas into it; combustion made the invisible flow visible. The nickname supplies permanence. Geology supplies the refill.