The Franconian Line was formed as part of the Variscan orogenesis and was most active between 100 and 50 million years ago, when the Fichtel, with its blocks of Hercyniangranite, pre-Hercynian gneissess and Palaeozoic metasedimentary rocks were uplifted above its forelands that were later filled with Mesozoic-Tertiarysediments. The vertical displacement is as least 1,000 metres (3,300ft) near Wirsberg and in some cases maybe close to 10,000 metres (33,000ft).