A tuff waterfall:
In karstic regions, infiltration water causes the formation of dolines (closed depressions in the relief) and other avens by dissolving the limestone. Most of the time, they reappear in the form of Vaucluse springs. A similar phenomenon exists in the Bonnan valley in the form of a petrified waterfall.
The event occurs during periods of high water. The water pours down in a tuff cascade (non-homogeneous porous rock, often powdery, in this case of sedimentary origin) over a height of about forty metres to cover the sandstone (stable mixture of rock and clay). A natural well collects them. Once underground, they resurface as a Vaucluse fountain at Gourp de Fénérols.
All year round.