These photos are from the exhibition Pierres secrètes: Mythologie préceltique en Forêt de Fontainebleau (Secret stones: Prehistoric mythology in the forest of Fontainebleau) at Musée de Préhistoire Île-de-France in Nemours.
The exhibition featured petroglyphs, or rock carvings, done on portable stones found hidden in the Forest of Fontainebleau. It seems like the rock art was intentionally hidden, such as in gaps between rocks, and not meant to be seen by casual passersby.
The photos were taken through the glass protecting the rock art, and the quality of many of the photos isn’t too good. But there aren’t that many photos of the Fontainebleau rock art online, so I’ll upload what I photographed at the exhibition.
The engravings are done on a type sandstone that is fairly soft and easy to carve into with simple tools. The blocks of sandstone also comes in different colors, and the color of the rocks may also have been important when selecting the stones for the engravings.
The petroglyphs in Fontainebleau is often separated into the Long Rocher style and the Malmontagne style. Long Rocher style engravings do not include figurative elements, and are mostly simple line markings or grid patterns. The Malmontagne style, on the other hand, do include figurative elements, and is done in a fairly unique style that separates it from other rock art, even when compared to other rock art in France.
Accurately dating rock carvings is difficult, but clues from archeological excavations in the area and what is depicted (in the Malmontagne art) indicates that these petroglyphs were made in the late Bronze Age (France is included in the Atlantic Bronze Age spanning 1300-700 BC). There is no clear evidence whether the Long Rocher and Malmontagne styles were used simultaneously or during different time periods. There are comparable motifs in both styles, and researchers favor the hypothesis of a direct succession of these two styles over time, with Long Rocher being the older.