The water from the Fontchaude natural water-spring refreshes the walker in summer.
This spring owes its name to the fact that it does not freeze in winter. This fairly constant temperature is due to the fact that the underground path is deep enough to be protected from outside temperature variations.

The thick layer of Upper Jurassic period limestone (from the Kimmeridgian period to the Tithonian period, 155 to 145 million years ago) is criss-crossed by cracks where water from the rain and snow seeps in and circulates. It is intersected by a faultline that brings the limestone into contact with impermeable marl (from the Valanginian and Hauterivian periods, 140 to 13 million years ago), which forces the water to flow out here.

In the Haute-Provence UNESCO Global Geopark, several other natural water-springs are fed by limestone: the Saint-Benoît spring in the heart of the Promenade Museum in Digne-les-Bains (Lias limestone), the Chanolles spring in Prads-Haute-Bléone (Upper Cretaceous period limestone).