The base of the Massif de l'Estérel dates from the formation of the Hercynian range in the antecarboniferous age and consists of a dozen layers of predominantly porphyric rocks. Volcanic outcrops appeared in the Permian 250 million years ago, during a thirty million-year period of intense volcanic activity that led to the formation of basalts and then red rhyolites. The initial volcanic structure (the Maure-Vieille volcano) disappeared under the effect of erosion.