 The Brendon Hills are to the east of Exmoor and are an outlier of it . They are separated from Exmoor by the valley of the River Avill . They have the same undulating landscape . The <unk> reach a height of 422 metres ( 1 @,@ 385 ft ) at <unk> Hill . Iron ore mining was carried out from Roman times up to the early 20th century . 
