The massif encompasses a number of mittelgebirges .
The massif consists of crystalline rocks , which are older than the Permian ( more than 300 million years old ) and therefore deformed during the Variscan Orogeny .
The massif encompasses a number of mittelgebirges and consists of crystalline rocks , which are older than the Permian ( more than 300 million years old ) and therefore deformed during the Variscan Orogeny .