Gotthard nappe

This outcrop begins west of the mountain ridge between the Binntal and the Goms (the valley of the Rhone) east of Brig.

The northern paragneiss zone contains lenses of various lithologies, such as calcareous schists, amphibolite, eclogite, peridotite (mostly thoroughly serpentinized) and gabbro.

The southern paragneiss zone contains characteristic hornblende-garnet schists called Garbenschiefer, part of the Tremola series.

The gabbros and peridotites, now lenses in the paragneiss, probably represent pieces of oceanic crust underneath these sediments, that were incorporated into the Ordovician accretionary wedge.

[1] In the late stages of the Ordovician orogenic phase, granitoid magma bodies intruded, especially granite.