Structural and petrological studies in metamorphic rocks of the Axial Zone and of the North Pyrenean Zone were able to prove the existence of incorporated Precambrian remnants. For example, in the basement of the Canigou massif and in the basement uplift of the Agly, the remnants of a Precambrian basement were discovered (recognised by radiometric dating on granitoids and by certain structures of tectonic origin), which were later incorporated into the Variscan orogen by tectonic movements and the associated metamorphism.