 The upland area is underlain by sedimentary rocks dating from the Devonian and early Carboniferous periods with Triassic and Jurassic age rocks on lower slopes . Where these reach the coast cliffs are formed which are cut with ravines and waterfalls . It was recognised as a heritage coast in 1991 . The highest point on Exmoor is Dunkery Beacon ; at 519 metres ( 1 @,@ 703 ft ) it is also the highest point in Somerset . The terrain supports lowland heath communities , Ancient woodland and blanket mire which provide a habitat for some scarce flora and fauna . There have also been reports of The Beast of Exmoor , a <unk> cat roaming Exmoor . Several areas have been designated as Nature Conservation Review and Geological Conservation Review sites . 
