Perched on a hill in the heart of the Vallée de la Blanche, this impressive block of sandstone was transported by the glacier into the Seyne basin over 20,000 years ago.
During the great glacial expansions of the late Quaternary, ice occupied the northern valleys of today’s Haute-Provence Geopark. The Durance glacier descended as far as the gates of Sisteron, while the Ubaye glacier overflowed its left bank to fill the Seyne and Turriers basins. Advancing through the Col Saint-Jean across the valley to the Cols de Maure and du Fanget, the glacier reaches a thickness of several hundred meters.
The Grosse Pierre is a geological curiosity, 5 meters high and 30 meters in circumference. This erratic boulder was transported by the glacier and left here when it melted. It’s an enormous piece of sandstone, weighing in at around 550 tonnes.
An easy, signposted walking trail (6 km, starting from the Place de la Mairie in Selonnet) will enable you to discover the boulder and its surroundings.
