The Alpilles mountains & the Costapera plateau
On the other side of the valley rises the Costapera plateau, site of the Celtic-Ligurian hill fort or oppidum which controlled access to the west coast. Traces of human presence have been found here dating back to 2000 years B.C.
This plateau is made of a calcareous rock, molasse, formerly called pierre du Midi (Midi stone) and containing shell strata. It can be found here and there throughout the Alpilles chain. From antiquity, the Romans used easy-to-sculpt limestone from the quarries of Saint-Rémy-de-Provence to construct numerous monuments, such as those at Arles and Glanum.
Erosion has created fantastical shapes in the rock and hollowed out numerous caves, like the Grotte aux Fées (fairies’ cave).