The Estérel displays several varieties of rhyolite, the crystalline volcanic rock giving the massif its characteristic orange-red color. They are spread over twelve levels, stacked on top of each other. The most important in volume is the ignimbritic rhyolite flow, also called amaranth porphyry of the Estérel, dated 272 million years ago. Rich in quartz phenocrysts and potassium feldspars, it forms several layers spread over practically the entire massif over a total thickness of 492 to 984 ft (150 to 300 m) and a volume of 37 cubic miles (60 km3).