Photo : GO69 / Wikimedia Commons (CC BY-SA 4.0)
Les Roches Tuilière et de Sanadoire
The Tuilière and Sanadoire rocks are two rocky pinnacles overlooking the glacial valley of Lac de Guéry, in the commune of Orcival, a few kilometres west of the Puy de Sancy, in the Monts Dore massif. The Tuilière peaks at 1,288 metres and the Sanadoire at 1,286 metres.
Both are volcanic chimneys, or dykes, of phonolite, a greyish rock that rings when struck: that is where the name Sanadoire, the "ringing rock", comes from. The Tuilière owes its name to the thin, regular stone slabs, the lauzes, once used to roof houses and churches in the region.
The two rocks formed at different times. The Tuilière resulted from a single rise of magma, about 2.2 million years ago, and shows regular prisms, volcanic organ pipes, that testify to slow cooling. The Sanadoire formed about 1.8 million years ago, through several successive injections of viscous lava. The two pinnacles can be seen very well from the road that runs along Lac de Guéry, which offers many viewpoints.
