The landscape in front of us allows us to trace one of the phases of geological development linked to the creation of the Alps; the Mélan thrust, or overlap. An overthrust, or overlap is the covering of one area of land by another another area of land.
The Mélan mountain, on the left, is made up of rocks dating from the Secondary Era: from the Triassic period (245 to 205 million years ago) to the Lias period (205 to 180 millon years ago). It abnormally covers Tertiary Era (or younger) terrains: the red marls, or swamplands of the Oligocene period near the Vançon river (34 to 23.5 million years ago), the sandstone rocky blocks of the Miocene period (23.5 to 5.3 million years ago) and the Mio-Pliocene period's mixed-composite conglomerate rocks, (like mixed-fruit cake pudding), at the Hill of Saint Joseph (8 to 1.65 million years ago).
Another element strongly marks the geological history of this area: the Aix-en-Provence fault-line leaves the course of the Durance river to guide that of the Vançon river. It is not visible here but its effects are: thermomineral springs and galena, the natural mineral form of lead, and barite mineralisation in Saint-Geniez, gypsum diapirs, or surfaced rock-formations around Authon. At the bottom of the valley, one can see large blocks of clear gypsum in the black marlstone rocks. These rocks, which are over 210 million years old, were initially formed at depth. They have moved, or been displaced to the surface through the fault-line. This phenomenon is called diapirism.
On a clear day, in the distance, you can clearly see the Durance valley and the rock-formation called Les Pénitents des Mées and you can make out the silhouette of the Sainte-Victoire mountain.
The sea is not too far away.