nappe

A large-scale geological fold structure in which rocks have been overturned and transported several kilometres or more by compressional stresses during mountain-building processes. The Alps consist of several such nappes.

In geology, a nappe is a large sheetlike body of rock that has been moved far from its original position. Nappes form during continental plate collisions, when folds are sheared so much that they fold back over on themselves and break apart.

Nappes or nappe belts are a major feature of the Alps of Europe. The Austroalpine nappes of the eastern Alps consist of a series of three thrust faulted nappe stacks which overlie the three older Penninic nappes in this very complex system.