The area centres on Slieve Gullion, the highest peak in County Armagh, measures roughly 42 by 18 kilometres (26 by 11 mi) and comprises some 150 km2 defined topographically by the hills of an ancient ring dyke.

[6][7] The composition of the remainder of the volcano today is dominated by gabbro and granophyre and is also the site of a noted occurrence of platinum group elements.

In terms of the development of this geology, some of the areas rocks date from the Silurian period when and formed part of an ancient ocean more than 400 million years ago Added to this landscape, the volcano added masses of molten granitic rock or magma, which forms the bedrock that underlies Newry town and much of the Slieve Gullion area.

[9] Along the contact zone between the Silurian rocks and the Newry granite a roughly circular fracture developed into which was intruded a series of acidic lavas.

Added to this complex interaction of pre-volcanic and volcanic activity,[11] the area was subject to the action of glaciers during successive Ice Ages.

The path offers access to both the cairns on top of the mountain and the lake, while the Courtyard Centre has a garden, refreshments and toilet facilities.

Close to the shore of the lake is an approximately one kilometre long tunnel, wide enough to drive an articulated truck into, which was excavated in the 1960s as part of a planned development intended to create a man-made cavern within Slieve Gullion mountain which was to have been used to store and release water to generate electricity.

In the Táin Bó Cuailgne (the Cattle raid of Cooley) Cú Chulainn is reputed to have defended Ulster, single-handed, against the armees of Queen Maeve of Connacht at the Gap of the North, which lies at the south of the area.

In another tale, Fionn Mac Cumhaill was bewitched by the Sorceress Miluchra on the summit of Slieve Gullion at the Lough of calliagh Bhirra and turned into an old, decrepit man.

Human habitation in the Ring of Gullion is said to have occurred for at least 6000 years and a rich inheritance of historic monuments survives to mark the duration of that settlement.

[15] Among the cultural and architectural heritage of the area are the following sites: From the Irish Doirse, which means 'Doors' or 'gates', this Iron Age earthwork is located at Dorsey on the western edge of the Ring of Gullion.

The structure consists of two roughly parallel massive earth bank and ditch ramparts over a mile long lie astride an old routeway to Eamhain Macha (Navan Fort, near Armagh – the ancient capital of Ulster).

Recent evidence dates part of the monument to around 100BC, contemporary with a major phase of activity at Navan and lending support to the tradition that the Dorsey was once the 'gateway' to Ulster.

The poet Eóchaid Rígéices is buried here according to the 11th century Laud Genealogies- Mac dond Óengus-sin Eocho Rígéices, qui hospitatus apud Daimíne & qui sepultus est in Domnuch Cuilind ("Aengus had a son Eochaid, the royal poet, who visited Daimine Daim Argat and who is buried in the church at Slieve Gullion").

[20] Most of the Ring of Gullion sits within the old Barony of Orior Upper within County Armagh, and lies within the boundaries of Newry and Mourne District Council.

In the west it also includes the valley of the Cully Water and the Umeracam River which separate the hills of the ring dyke from the rolling drumlin landscape extending towards Crossmaglen and Cullyhanna.

ESA designation is a voluntary scheme which provides financial encouragement for farmers to adopt farming practices which maintain and enhance the landscape, wildlife and heritage of their land holding.