La Limagne – the organs of Usson, and the Sailhant waterfall.

Near Issoire, the village of Usson is built on an old basalt peak, which culminates at 639 meters.

This surprising geological formation is linked to a phreatomagmatic eruption, resulting from the contact of lava with water. The region was then a vast lacustrine zone, in which the magma made its way.

This volcanism began 25 Ma ago, and is older than the volcanic events that gave rise to the volcanoes of Cantal, Mont-Dore or those of the chaîne des Puys .

The organs, located south of the village, are the remains of the deep part, the chimney of an old volcano which has now disappeared under the effect of erosion. Usson's vertical organs are cooled from above, not from the sides of the chimney. The regularity of the prisms is also associated with a rather slow cooling.

The village, classified among the most beautiful villages in France, was built thanks to the hexagonal prisms, and the arkose, visible in the walls of the church of St Maurice.

The Castle of Usson, demolished on the order of Cardinal de Richelieu, had previously been, from 1585 to 1605, the place of house arrest of Marguerite de Valois (1553-1615), nicknamed by Alexandre Dumas Queen Margot, first wife (1572-1599) of King Henry IV of France.

The Château du Sailhant, in the commune of Andelat, was built in the 13th century on a triangular basalt spur, about 20 to 25 meters high.

It is also known for the presence of the Sailhant (or Babory) waterfall nearby.

 The Babory stream flows from a height of about twenty meters at this point into a chasm whose depth is estimated between 6 and 7 meters.

Sources:
- Futura - The Exploratorium: the organs of Usson in the land of volcanoes.
- Sailhant castle - wikipedia