Volcano, natural and geological heritage in Meyras in Ardèche

Opening : All year round.

The volcano of Souilhol and its two flows and the maar Doris, are linked to the last eruptive episode that affected the Bas Vivarais in the town of Meyras and its Young Volcanoes of Ardèche.

The Souilhol volcano sits 680 metres above sea level on the heights of the Neyrac-les-Bains spa in Meyras, in the direct confluence between the Ardèche and the Lignon. Souilhol is therefore part of the Young volcanoes of Ardèche, in the same axis as the Maar Doris and the Gravennes (Thueyts side and Montpezat-sous-Bauzon side) and it is linked to the last eruptive phase of volcanoes in Bas-Vivarais. Its two flows were created during an explosive phase and then an effusive phase.

Would you like to discover this unique place? Go hiking up the Souilhol volcano by following our itinerary here

The course of the Souilhol volcano flows 

The crater of this Strombolian volcano, currently extinct, is regularized with two basaltic flows well visible in two different directions: the first, oriented south-east, went in the direction of the valleys of Lignon and Ardèche, to Pont de Labeaume where it covered the Ray-Pic flow; As for the second, northwest side, it bypassed Neyrac-Haut (above the spa) before hitting the mountain, this trajectory would be due to a fracture affecting the base from which the magma rises (which also explains the continuity of its volcanic appliances).

Why is the Souilhol volcano different from the others?

However, Souilhol is distinguished from other volcanoes by its typical characteristics of Hawaiian volcanoes: a lava whose fluidity and temperature are very important: up to 1200 degrees Celsius! The Souilhol and its eruptions formed several volcanic products including ribbon bombs, Pelé hair (fine filaments of rocks named so in honor of the Hawaiian goddess of fire) and bombs with «bread crusts», these surface projections due to the exhaust gas contained in the bomb. The high temperature of the Souilhol lava gave its projections a very particular form called «twisted».

Souilhol also has one of the biggest volcanic bombs of the territory with its impressive characteristics between 7 and 10 tons for 1m3!

Souilhol is one of the 7 volcanoes in France to present «basalt crying», it is so called because the rock contains carbon dioxide mixed with traces of water that sometimes rise to the surface in contact with the air, with condensation, like tears…poetic is not itthat’s right? After the cooling of the lava, the Ardèche cut this flow by recreating its bed, highlighting the internal structure of the flow and in particular the basalt organs of the true colonnade.

The basalt flow and basalt organs of the true Souilhol colonnade measure in places up to 10 meters high! Even if they finished their races in the same valleys (Ardèche and Lignon), the Souilhol flow is prior to that of the volcano of the Jaujac Cup.