<P> Folds and thrusts north of the Periadriatic seam are generally directed to the north, the dominant vergence (direction of fold asymmetry) in these units is to the north . In the Southern Alps the thrusts are to the south so the vergence is dominantly southward . </P> <P> The rocks of the Austroalpine nappes form most of the outcrops in the Eastern Alps, while in the west these nappes are, with the exception of a few places (the Dent Blanche and Sesia units), eroded away . In the Western Alps the Helvetic nappes can be found to the north and west, sometimes still under klippes of the Penninic nappes, as in the Préalpes du Sud south of Lake Geneva . </P> <P> In many spots in the central zone north of the Periadriatic seam large antiforms called anticlinoria can be found, sometimes they are displayed in the outcrops as windows . At the level of one of these windows (the Hohe Tauern window) the Periadriatic seam curves to the north, which suggests that the Apulian plate is more rigid in this particular spot, working as a so - called indentor . </P> <P> In the central part of Switzerland uplift took place along a ductile north--south normal faultzone called the Rhône - Simplon line . The structure thus formed is called the Lepontin dome . </P>

Where were the rocks found at the top of the alps mountains originally formed