The Frilihorn Nappe is a thin Upper Penninic tectonic unit intercalated within the Tsaté Nappe in the Val d’Anniviers, Zermatt Valley and Valtournanche. It is composed of a series of Briançonnais-type Permian–Triassic sediments overlain by Jurassic breccias and limestone and calcschists probably of Cretaceous age (hence quite similar to that of the Mont Fort Nappe).