Basalt rock at the basis of Rochemaure castle

Plate II from Barthélemy Faujas de Saint-Fond's volume entitled, Recherches sur les volcans éteints du Vivarais et du Velay. Faujas de Saint Font was a geologist and the French commissioner for the mines. In this volume, he developed a theory about the origins of volcanoes which he strengthened based on observations of basaltic rock formations.
Plate II shows a basaltic formation near Faujas de Saint Fond's hometown of Montélimar.