The Picard ponor

In karstic landscapes, ponors are formed when naturally acid waters enter into fissures and dissolve the limestone rock. Located on the edge of a dry valley, the Picard ponor attests to the former presence of a stream discharge that filtered into the rocks in this exact place. Often, ponors are connected to a network of underground galleries into which rivers run. Since 1987, colouration has proven that the waters running through the Picard ponor resurge 3 km further along at the Bief Noir source, one of the Flumen’s affluents, between Septmoncel and Saint-Claude.