These prealps are made up of clayey limestone (molasse), with karst rock on the high altitude plateaus.

The mountains show limestone and dolomitic formations of Jurassic age affected by folding and thrusting with an east-west orientation.

The high altitude plateaus have a gentle topography and the characteristic features of a limestone landscape attesting to very developed karstification: lapiaz, sinkholes, dry valleys, temporary flow losses and caves.

[2] All the sedimentary layers which were deposited above the gypsum will detach, slide, break, become entangled which defines secondary terrain on tertiary.

The movement of the plates continues but since the sedimentary soil is karstic, it erodes more quickly than the crystalline rock of the old Precambrian massifs such as Estérel and Maures.