The Montagnes Noires (French: 'the black mountains'), also known as the Montagne Noire (French: 'the black mountain')[1] and in Breton as Meneziou Du[2] are an east-west oriented range of hills in Brittany centred around the town of Gourin. They culminate in the peak of Roc de Toullaeron (Breton: Roc'h Toull-al-Laeron) which attains a height of either 318m[3] or 326m.[4] Other significant peaks include Ar Menez (304m) and Montagne Noir (307m) (or, in Breton: Menez Du).[5] They are composed from a range of Precambrian, Ordovician, Silurian and Devonian rocks forming a part of the Variscan orogen and include sandstones, quartzites and slates.[6]
The hills form a part of the border between the départements of Finistère and Morbihan and just extend into Côtes-du-Nord.