Eternal Flame Falls, in Shale Creek Preserve within Chestnut Ridge Park in western New York, is known for a rare natural gas seep in a grotto behind the waterfall that can be lit to create a flame behind the falling water. Scientific study has shown the seep contains an unusually high proportion of ethane and propane and likely rises from the Rhinestreet Shale through tectonic faults about 400 meters below the surface. Researchers suggested it may reflect a poorly understood way gas forms in relatively cool shale. Growing popularity in the 2020s brought damage, and trail improvements in August 2023 made access safer though still difficult.