Landscapes
Landscapes
The Ring of Gullion is the most spectacular example of a ring-dyke intrusion in the British Isles. The rocks of the area are complex and have featured in international geological debate over the past 60 years or so. The site has attracted geologists from all over the world and featured in a number of new theories that have been put forward to explain the unusual rock relationships. Some of these theories have now become an accepted part of geological science.
Camlough Lake
The oldest rocks in the area formed in an ancient ocean more than 400 million years ago during the Silurian period. Masses of molten granitic rock or magma, were later intruded into these rocks, which underlie Newry town and much of the Slieve Gullion area. These granites are some 390 million years old and date from a major period of mountain building in Ireland.
Slieve Gullion and the Carlingford Peninsula owes much of its origin to a time of volcanic activity during the Tertiary period around 65 - 50 Million years ago. These volcanic eruptions and events are linked to a time when the continents of Europe and America began to move apart creating the Atlantic ocean and the landscape and geology are similar to that of the Isles of Mull, Skye and Aran in Eastern Scotland. The most recent theory on the sequence of vents believe that Slieve Gullion was the first major volcanic event, Carlingford was the second and the final stage was the granitic intrusions of the Mournes.
Slieve Gullion is a huge whale shape mountain surrounded by a ring of hills known as a ring dyke. This unique landscape is composed of three distinct units the earliest of which is the outer ring dyke a clearly defined series of hills surrounding Slieve Gullion up to 300m in height, some 11km in diameter. These hills were formed by an influx of acidic magma forming granophyre. The most common theory on its formation is that it intruded after the 'ring dyke' and, theories behind its emplacement are complex and t was the subject of a fascinating debate in Irish Geology. The third and final phase of the complex's history was the intrusion of a small area granite around the south eastern edge of the ring at Foughilloutra.
Summit of Slieve Gullion
After the initial phase of volcanic activity the rocks of the area were worn down by the processes of air, water and wind to begin the shaping of the modern landscape. A major factor was however to speed up this process of erosion - ICE. Around 1.6 million years ago much of the island of Ireland and mush of western Europe was subjected to a series of 'Ice Ages'. The main ice which effected south Armagh and south Down formed further north and began to flow over the Carlingford Peninsula from the north west to the south east. The moving ice scraped the hard surfaces of the volcanic rocks and exploited any weaknesses creating a deep, steep sided U' shaped valley at Carlingford Lough.
The harder volcanic rocks of the Ring of Gullion, Slieve Foyle and the Mournes resisted the erosive powers of the glaciers while fault lines such as Camlough, and bands of weaker rock such as Carlingford Lough were scoured out by moving ice and flowing melt waters. The peaks of the three mountain ranges stood firm and all now lie at over 500m in height:- Slieve Gullion 573m, Slieve Foyle - 589, Slieve Binnian - 747m and Slieve Donard - 850m. The areas which had been breached by this glacial erosion later became migratory route ways through which people, animals and plants have migrated into the area.
The effects of glaciation did not only have a destructive or erosive impact on the landscape it also deposited material creating what is known as a drumlin landscape of small rounded hills which stretch from the western coast of Ireland at Sligo, Leitrim and southern Donegal through Cavan, Monaghan, and into South Armagh and South Down. These small rounded hills were deposited silts and clays as the glacier lost its ability to carry material and was forced to deposit t. The hills were shaped by the ice retreating back as conditions warmed and the Ice Age ended around 12,000 - 15,000 years ago.
This glacial deposition in the Mournes has also led to the deposition of large quantities of sand and gravel along the coastal plains creating many large granite boulders 'erratics' on the slope of the mountains one example being 'Cloghmore Stone' in Kilbroney Forest Park, Rostrevor and the tail on the south- eastern edges of Slieve Gullion.
The effect of the above geological processes and the underlying geological bed rock has been a significant factor in creating the various landscape 'zones' which we know find along the Carlingford Peninsula. The landscape around Carlingford Lough can be broken down into nine distinct areas each of which have their own unique characteristics and management issues
