The Ardey Hills, together with the Haarstrang, run from east to west, separating two major natural units: the Westphalian Lowland including the Emscher Depression and Hellwegbörde in the north from the Süder Uplands and lower Sauerland in the south, the Ardey being counted as part of the Süder Uplands and the Haarstrang the Westphalian Lowland.