 The main range of hills on Rùm are the Cuillin , usually referred to as the " Rùm Cuillin " , in order to distinguish them from the Cuillin of Skye . They are rocky peaks of basalt and gabbro , similar in many ways to their better @-@ known namesakes . Geologically , Rùm is the core of a deeply eroded volcano that was active in the Paleogene era some 66 - 23 million years ago , and which developed on a pre @-@ existing structure of Torridonian sandstone and shales resting on Lewisian gneiss . Two of the Cuillin are classified as Corbetts : Askival and <unk> , ( Old Norse for " mountain of the ash trees " and " hill of the strongholds " respectively ) and Rùm is the smallest Scottish island to have a summit above 762 metres ( 2 @,@ 500 ft ) . Other hills include Hallival , <unk> ( ' mountain of the trolls ' ) , Barkeval , and <unk> nan <unk> ( Gaelic : " peak of the young men " ) in the Cuillin and Ard Nev , Orval , Sròn an t @-@ <unk> and Bloodstone Hill in the west . It is likely that only the higher peaks remained above the Pleistocene ice sheets as nunataks . 
