Geological map of the Apt Basin (modified after SIT-PNR-PACA-Luberon, http://sit.pnrpaca.org/pnr_geologie/index.html), highlighting the name of the nine localities discussed in the text: Murs village (in the Murs Graben; MG), La Rabotte farm (LR), Goult village, Saint Hilaire monastery (SH), La Coquillade hill (LC), the Perréal Graben (PG), Apt city, Jean-Jean hamlet in Apt (JJ), and the Dog Head cliff (DH).