The landscape in front of us can be broken down into two distinct geological areas or zones.

The indigenous terrain (land which was deposited there and has not been subsequently displaced) extends in front of us to the base of Mélan Mountain. This indigenous terrain includes, in the south, the Hill of Saint Joseph and, in the north, all the land up to the base of the Trainon mountain. These geological-formations are dated to the Tertiary period and the Quaternary period.
The parautochthonous terrain (land which has been displaced from its original place of deposition) constitutes the whole area of the ridges: Mélan mountain, Monges mountain and Trainon mountain. At the base of these ridges, whitish gypsum outcrops can be seen. It is the gypsum that has allowed the displacement, or shifting of these lands, whose deposition dates from the Secondary Era.

In the Municipal District of Saint-Geniez, gypsum was mined for a long time for the manufacture of plaster but also for the extraction of alabaster (finely crystallised gypsum used in sculpture). The site of Saint-Geniez was known very early on for its deposits of useful rocks: coal, silver sulphide lead, marbles, etc. These small mines have now been abandoned due to lack of economic viability.