On a boulder along La Route des Barnolets, near the bivouac of Bourron-Marlotte. Standing start with an undercling left hand and climb the left side of the arete.
From the bivouac of Bourron-Marlotte, follow La Route de la Grande Vallée for 200m and take La Route des Barnolets on the right. The boulder is 250m further, on the right of the path.