Exploring Slieve Gullion and its interesting geology

Ascending Slieve Gullion with a view southwest to the outlying hills which form the ring of volcanic hills surrounding Slieve Gullion. The village in the gap between the two hills is Forkhill and beyond is County Louth.

So here was my plan. Leave Macclesfield at 5am, get a lift to Manchester Airport for the first flight out to Belfast City Airport. Collect my hire car and get provisions for a few days then head down to County Armagh to climb the hill called Slieve Gullion and be walking by 10am. It seemed an ambitious plan and having negotiated the Belfast rush hour I was parked up and ready for the off at 09.45am from the Slieve Gullion Interpretation Centre in South Armagh and furthermore it’s was a fine and sunny October morning.

On my first visit to the area in 2003, the observation watch towers were still in place along the border. Ten years later, the towers had gone but being close to the Irish border and not knowing what to expect, I was a bit dubious about walking here due to its past terrorist history as just down the road were the two villages of Forkhill and Crossmaglen both of which often featured in the news for all the wrong reasons. I needn’t have worried as the site was well used by walkers and the place where I set out from had a complex of buildings including a café, toilets and detailed information boards of the area explaining the rich geological history.
Geologically Slieve Gullion and the encircling ‘ring dyke’ hills are considered to be the best example of a volcanic ring dyke system in the British Isles The complex attracts international research interest and has made contributions of world significance to scientific understanding of volcanicity.
The oldest rocks date from the Silurian period 440 million years ago and were laid down under the sea bed then 30 million years later, molten granite rock was intruded into these rocks which spread as far as Newry as few miles away. This volcanic activity formed an important part of mountain building in Ireland
Around 65 million years ago during the Palaeogene period, the area saw further volcanic activity and Slieve Gullion today forms the heart of an ancient volcano. Ring faults around Slieve Gullion form an interesting circle of hills some seven miles in diameter.
So why had I come to climb, Slieve Gullion? Well, it just so happens to be the highest piece of land in County Armagh and therefore a county top. I had only two ‘county tops’ summits to bag in Northern Ireland and with the weather being good I set out on this recognised nine mile circuit.

The trig point and toposcope at the summit of Slieve Gullion and the view south towards County Louth.

The passage tomb at the summit of Slieve Gullion. Probably a good lunch stop out of the wind! I decided not to put it to the test.

With a fine sunny morning I set off up through Hawthorn Wood from the Interpretation Centre but already the map and information I had didn’t agree as I should have been higher up the hillside. I continued with a good path and knew exactly where I was. Soon the views to the south began to open out towards Dundalk and County Louth. With a little bit of a dog leg on a unmarked path, I managed with ease to get onto the intended route, which was a deserted forest drive albeit a few dog walkers. The drive skirted around the lower southern slopes of Slieve Gullion gradually ascending and views opening out across the vast expanse of green fields towards County Monaghan. As I ascended so the circuit of rocky hills around Slieve Gullion were becoming more prominent and the geological landscape was giving up its secrets.

Reaching a high point on the forest drive I stopped for my morning break and soon left the drive up an engineered path on my right. This good path ran all the way to the 576 metre summit. The summit was a cold place and no spot to linger. The sunshine of earlier had gone and fleeting showers were around. The view however was excellent with the visibility extending to Sugarloaf Mountain south of Dublin some sixty miles away. Below the trig point and toposcope is a large chambered passage tomb, the highest of any such tomb in Ulster. The entrance to the tomb is along a short, lintelled, passage which leads to the octagonal, originally corbelled, chamber.The earliest documented investigation of the tomb dates from 1789 when only a few bones were found and another archelogical imnvestigateion in 1961 revealed that the tomb had probably been ransacked and little was found.

A pleasant grassy path descending north from Slieve Gullion and a view to the ring of volcanic hills that surround Slieve Gullion.

Sunlight catches Sugarloaf Hill, north of Slieve Gullion.

I decided to set off for North Cairn which lies at the northern end of the ridge. In contrast with the walk so far the going was quite boggy in parts and a slip I took resulted in an awkward fall onto my thumb. Thankfully, I didn’t break it but it was a close thing. From North Cairn I descended north towards the Ballard Road carefully treading on any sloping boggy ground. Lower down at a drier spot, I found a good sheltered spot for my picnic lunch staring out across County Armagh and County Down. Setting off once more, the path became very good and well defined as I descended that last half mile to the Ballard Road. It was all road walking now back to the car and turning east, I soon made a winding descent to continue with the road running south below Slieve Gullion. There was the odd shower around but not enough for waterproofs.

Tree felling on the slopes of Slieve Gullion. Its amazing what this bit of kit can do. Grabbing each tree, felling, stripping the branches and cutting into lengths takes as little as forty seconds.

Clonlum South Cairn near Meigh. One of many prehistoric monuments in this area.


I paused at three locations en route back to the car. Firstly I stopped below Ballintemple Wood and watched a machine at work felling pine trees. Easy work was being made as each tree was grabbed by claws and the powerful saw cut through tree trunk then felled and the trunk stripped of branches and cut into equal lengths with each tree only taking around forty seconds to process. Next on the agenda was Killevy Old Churches which date from the 5th century AD and started out as a convent. Two churches were built next to one another in a peaceful setting and surrounded by a graveyard. Today the buildings are roofless. Finally, a short detour was taken into a field to visit Clonlum South Cairn. A Cist, surrounded by a raised bank lying in the middle of a field. I continued with the road back to the car finishing the walk by mid afternoon.
So to sum up the walk is that I was pleasantly surprised by the good facilities at the start and overall the paths were good in this area where few walkers would have dared to tread only a few years back. There are plans for a network of paths in the area. It is now a case of attracting people into this area of interesting scenery.