![Source du Bief de la Ruine et Creux des Joyaux](https://en.montagnes-du-jura.fr/uploads/external/d499a0ed24ef-Sourcedubiefdelaruine-foncinelehaut-printemps-2023--Jean-Marie-Combette-Peter--1-1440x900.jpg)
Source du Bief de la Ruine et Creux des Joyaux
The Bief de la Ruine spring
The Bief de la Ruine is an intermittent stream that takes its name from the hamlet of Les Ruines, and only comes to life after heavy rainfall or when the snow melts.
Many years ago, the stream flowed continuously, but a collapse at its source created an underground lake that meant it could no longer maintain its flow. Now, it is only when its network reaches saturation and the lake 'overflows' that the water manages to find its way between the limestone walls of the massif, allowing the reach to gush out in an impressive waterfall.
Its source lies in the heart of a limestone cirque. Originating from the same underground lake as the Saine, the stream flows under the Bayard before spurting out, sometimes very suddenly, under the rocky porch. It is made up of a succession of remarkable natural sights, including the Creux des Joyaux, which is accessible via the stream bed when the water level permits (Warning: you may be surprised by the sudden onset of water and rock falls are frequent. It is forbidden to go there in the event of flooding).
Le Creux des Joyaux
Le Creux des Joyaux is often dry. But when the Bief de la Ruine is in flood, the stream gives rise to a waterfall that, along with the current, causes the sand and pebbles in the hollow to swirl around. Once the water is clear and peaceful again, the "jewels" sparkle in the sunlight.