This "natural arch" is located on Rocher de la Dragonnière above the hamlet of Sainte-Colombe near the village of Orpierre in Hautes-Alpes department of France. The opening has a measured span of 15.5 metes.  IGN topographic map map top 25 number 3239 west Rosans pleat C9. The opening may be not qualified has "natural". There are some mines on the hill below the arch with made-man openings.  However, after careful examination of the span, the author found any blast marks or blasting alteration. Also, it is possible that opening was formed after blasting shock waves repetition on the pit below. If anyone can be provides information about the story of this area, please contact the author guildebo@hotmail.com