Puy de la Vache, Scoria cone volcano in Puy-de-Dôme, France

Puy de la Vache is a breached scoria cone of the Chaîne des Puys, 1167 m high and about 130 m above its surroundings, with a 350 m-wide crater open to the southwest. Its slopes show dark ash, lapilli and scoria, with larger bombs and reddish oxidised scoria near the top. A path follows the crest to the summit.

The Puy de la Vache and its twin, the Puy de Lassolas, were born from the same eruptive fissure about 8,400 years ago, making them the youngest volcanoes of the Chaîne des Puys. Their Strombolian eruption built two scoria cones, and the escaping lava broke the southwestern crater wall, giving both cones their breached, south-facing form. The combined flow, the cheire d'Aydat, ran 15 km southeast as far as the sites of Saint-Saturnin and Saint-Amant-Tallende.

The name "Vache" (cow) is said to come from the shape of the breached crater, which herders likened to a cow's horn. The twin cones of La Vache and Lassolas are climbed from the Maison du Parc near Aydat, and the red scoria at the rim, oxidized by heat and fumarole moisture, contrasts with the black lapilli lower down.

The walk starts from the Maison du Parc des Volcans d'Auvergne near Aydat and leads to the foot of both the Puy de la Vache and the Puy de Lassolas. The crater rim is reached on foot; the south-western wall is breached where the lava escaped. A former quarry in an adventive crater at the foot of the Puy de la Vache was worked until 1980.

The 15 km lava flow, the cheire d'Aydat, dammed the Veyre valley and left the lakes of Aydat and la Cassière. Scoria that fell back onto the flow's back made its surface chaotic. Rare phenocrysts, large crystals set in the volcanic rock, can still be found on the site.