Franconian Forest
In the next phase, great, deep-sea sediments were laid down under the present-day Fichtel Mountains and the Franconian Forest from the Silurian, Devonian and Lower Carboniferous periods; these are especially well recorded in the Franconian Forest, whose rocks were only subject to very low-grade metamorphism (associated with volcanism and ore formation) and which contain easily dated fossils. Finally, in the Upper Carboniferous period 285 million years ago, the Hercynian mountain building phase began and raised the Fichtel Mountains, Franconian Forest and Münchberg gneiss plateau into high mountains – like almost all the fold mountains formed during the Hercynian period.