The Harz is a fault-block range, that rises abruptly from the surrounding lowlands in the west and northeast and gradually dips towards the south. It is dissected by numerous deep valleys. North of the hills lie the Cretaceous layers of the sub-Hercynian depression in the rolling hills of the Harz Foreland; south of the Harz, Permian sediments lie flat on southwest-dipping Palaeozoic beds.