This 17 acre glen is made up of various trees including oak, beech, ash, willow and birch. The Cornaa River cuts through the slate forming small cascades and waterfalls which were used by the two mills once situated in the glen. In Spring it is carpeted with bluebells.
The larger of the two mills, found in the glen, was used for grinding corn up until 1951 while the smaller was used for flax. In 1952 the glen was acquired by the Forestry Board as a National Glen.
From 1854 to 1857 and again in 1866 to 1867 The Great Mona Mining Company extracted lead, zinc and copper from the river bed and the buildings and wheel house still exist.