Geology: after invading the Parisian Basin for the last time some 37 million years ago, the sea deposited a huge quantity of very fine and pure sand that in some areas reached a thickness of 60 meters. In the Quaternary era, long after the sea withdrew, a very complex evolution took place and some sandy zones were solidified by the silica contained in water, forming sandstone beds in the sand called “platières”. Freed by erosion, their borders collapsed thus creating the Fontainebleau sandstone boulders arranged in spectacular chaos.

The Brigand cavern: it is the work of Claude François Denecourt. This cavern has 2 entries linked by an underground tunnel. Claude François Denecourt, who invented nature tourism, invented as well the legend whereby this cavern would have served as a den of bandits under the reign of King Louis XV.