Aerial picture (Google Earth^©) of a sandstone lens in the Fontainebleau area (Location Fig. 1). The sandstone lens forms a plateau (also called “platière”) surrounded by valleys in the sands. A. Raw picture and coordinates. B. Highlight of the lens limit and fracture pattern (white lines). The main joints direction is N120°, oblique to the N100° lens limit, discarding gravitational origin of the fractures. The secondary N25° joint set is also highlighted. C. Two rose diagrams of fracture orientations in the Fontainebleau area published by Obert (1984) – N: number of data.