The Mont Mary Nappe is constituted by two crystalline basement units: a Lower Unit mainly comprising pre-Alpine amphibolite-facies paragneisses with minor amphibolites and orthogneisses and an Upper Unit comprising pre-Alpine amphibolite- to granulite-facies paragneisses with mafic and carbonate rocks.

High-grade pre-Alpine paragneisses (kinzigites auct.), amphibolites, marbles and minor spinel-amphibole harzburgites.

Granitic ortogneisses and paraschists.