A very compact cliff!

On the other bank of the Berthéou valley, it is possible to see a light-coloured, almost white, cliff: it is made of quartzites from the Triassic period, resting directly on top of the recognisable red pelite of the Paermian era.
This extremely compact rock was used on site to build the beautiful Berthéou viaduct, constructed at the beginning of the 20th century for the steam tramway which ran to Guillaumes.
Quartzites can mainly be found in the “giant’s cauldrons” in the Berthéou valley, where they played an essential abrasive role. These natural swimming pools are a delight for fans of canyoning.