 In addition to the Exmoor Coastal Heaths Site of Special Scientific Interest (SSSI), two other areas are specifically designated. North Exmoor covers 12,005.3 hectares (29,666 acres) and includes the Dunkery Beacon and the Holnicote and Horner Water Nature Conservation Review sites, and the Chains Geological Conservation Review site. The Chains site is nationally important for its south-western lowland heath communities and for transitions from Ancient woodland through upland heath to blanket mire. The site is also of importance for its breeding bird communities, its large population of the nationally rare heath fritillary butterfly (Mellicta athalia), an exceptional woodland lichen flora and its palynological interest of deep peat on the Chains.
