On the boulder of Bicarburation, at the end of a quarry, under the plateau, to the left of de La Route des Gorges de Franchard, in direction of La Gorge du Houx. Start at the right angle, traverse on the ledge and exit via a mantle at the left angle.
Access : at the end of the paved road, go up the hill to the plateau; the boulder is behind a tagged shelter at the end of the quarry.