The Grand Som is a mountain of the Chartreuse Mountains in the French Prealps, in

Isère Isère ( , ; frp, Isera; oc, Isèra, ) is a landlocked department in the southeastern French region of Auvergne-Rhône-Alpes. Named after the river Isère, it had a population of 1,271,166 in 2019.Col de la Ruchère The Col de la Ruchère is a mountain pass located at 1,407 m above sea level, in the township of Saint-Christophe-sur-Guiers in the Chartreuse Mountains between the ''Riondettes'' meadow at La Ruchère and the Grande Chartreuse monastery Gr ...

northwest and the

Grande Chartreuse monastery Grande Chartreuse () is the head monastery of the Carthusian religious order. It is located in the Chartreuse Mountains, north of the city of Grenoble, in the commune of Saint-Pierre-de-Chartreuse (Isère), France. History Originally, the ch� ...

below the cliffs. The summit has a cross and two relief tables. It lies in the

Parc Naturel Régional de la Chartreuse Parc Naturel Régional de la Chartreuse (Chartreuse Regional Nature Park) is a regional nature park located in the region Rhône-Alpes between Chambéry, Grenoble and Voiron, on the border of the departments of Isère and Savoie. It is based on the ...

Caving

Many chasms are present on the massif: Trou Lisse à Combonne (−303 m), puits de l'Écho (−396 m), gouffre Roland (−481 m), gouffre de Mauvernay (−507 m), gouffre des Aures (−512 m), , but the most important network is the puits Francis (1,565 m) or of 723 meters deep for 6,836 m of development. Discovered in July 1966 by the caving club of La Tronche (FLT), the siphon at (−688 m) was reached on August 23, 1967. Upper entries were then found..

References

Mountains of Isère Mountains of the Alps Chartreuse Mountains Two-thousanders of France {{Isère-geo-stub