Travel on a good day from Dublin towards Dundalk and the north-east coast appears in the distance as a barrier of steep and rugged hills. Across the broad bite of Dundalk Bay the view is clear. The line of hills above the sea is a graduated blue, as if it had been dipped in sections. These are the Cooley Mountains in Carlingford and, further north, the rocky ridge of the Mournes on the coast of Co Down.
Left of the Cooleys, seen from the south, is a gap where teeth have been extracted; left again, a single peak. The mountain is Slieve Gullion; the low ground contains the Gap of the North. The Dublin-Belfast road runs through it, just as Sli Midluachra, the ancient road from Tara to Eamhain Mhacha, did 2,000 years ago.
Steep, rocky hills, outliers of Slieve Gullion, are crowned by army towers, lookout posts. Helicopters come and go. On a hill by the Gap of the North stands Moyry Tower, an Elizabethan outpost. The walls are intact, complete with musket loops. Built in 1600 to house a dozen soldiers, it protected the northern access to the Pale.
No doubt the Men of Ulster, 2,000 years ago, had lookout towers as well. Tain Bo Cuailnge, the epic cattle raid, fixes the importance of this terrain in the Iron Age.
We climbed Slieve Gullion for the first time in February this year: the last hill walk before the foot-and-mouth crisis. It took tenacity to get there, resisting the lure of the Cooleys and the Mournes. There is a thicket of minor roads north of Dundalk, the signs less than garrulous, in the style of south Armagh.
Skirting the foot of the mountain, probing for access, there is a sense of absorption, of moving into the past. The boundaries tighten, closing in. There are rough stone walls tumbled in wild grass, old houses in fields of furze and fern, steep boulder-studded grazing, hedges of unpruned ash and blackthorn - not the vigour of fresh growth but the residue of age, gnarled and knotted. The scenery is sometimes astonishingly sweet, as when a view selects a spread of open slope, the back end of a valley where old ladder farms slope downhill, stepped with walls and hedges, each narrow strip sharing the variations in the land, from well-drained ridge to marshy sump.
In 1991, it was designated an area of outstanding natural beauty, with protection for wildlife, heritage and amenities. It was later designated an environmentally sensitive area.
But just when we should be moving onto open ground, there is a brutal brush with conifers: the occupying force of a monoculture. Sitka spruce trees march round the ancient mountain, in time, in line, in step, in uniform grim and green. The hillside, when it opens out, is steep. This is what "gullion" promises. Those who assume the word derives from "cuileann" (holly), as many place names do, may well be wrong: there is an older "cuilleann", meaning a steep unbroken slope. You won't find it in a modern dictionary, or even in Dineen's treasury of verbal tangents. (You'll find distractions, though, such as "cuilleann Muire", meaning withered Christmas holly, one of those presences so stark and thorny that it deserves a name.)
Legend loosely ascribes the mountain to Culann, the smith who also gave his name to Cuchulainn.
The open slope looks tedious, upholstered in bushy heather, but it's riddled with sheep paths - and trenches worn by walkers. Slieve Gullion has been at the heart of a military zone for decades, but it hasn't escaped the arhythmic tramp of the civilian boot.
Walking uphill, no matter how you romanticise it, is intrinsically dull. The value lies in the surroundings. Slieve Gullion is a volcanic mass surrounded by a dyke of rocky hills, the rim of a huge explosion 60 million years ago. The hard-edged outer circle, rusty with fern and heather, is the Ring of Gullion, which is 10 to 12 kilometres across. Uncanny in its symmetry, it cries out for myth. You think of a ring of dancers turned to stone . . . but that's too pastoral. There was a brutal upthrust here: Slieve Gullion protrudes into south Armagh like an armour-piercing shell, torn landscape raised in a thorny wreath around its cone.
The names of these hard hills are a ring dyke in themselves: Sturgan, Slievenacappel, Mullaghbane, Slievebrack, Croslieve, Tievecrom, Slievebolea, Feede, Flagstaff, Fathom, Camlough.
On the summit of Slieve Gullion, the February wind comes from all directions, as if every quarter has its own abusive breath and finds a focus in our presence. The country below spreads out the winter map of itself.
There's a cairn on the northern summit, a slump of stones where two Bronze Age burials were found. A modest cairn and passage grave stands farther south. Given the centrality of Slieve Gullion to a vast landscape, it's surprising there isn't evidence of greater ceremony on its summit.
Fionn Mac Cumhaill had a nasty accident here. He was tricked into a nearby lake by a malicious former lover. The water turned him into a withered old man. In revenge, the fianna attacked the summit cairn, the dwelling of Cuilleann, father of the girl. Under extreme duress, Cuilleann gave Fionn a drink of water, reviving him - except for his hair, which remained grey. (Interesting to compare this late medieval story with the tradition of Fionn's ability to deliver a life-giving drink of water - and his refusal to do so on the summit of Slieve Gulban/Benbulbin, thus causing the death of Diarmuid, his rival in love.)
A plinth on the very top of Gullion has a metal plate showing principal points in the landscape as far away as the Mournes and Wicklow. Among the radii, a careful line points out, without a hint of irony, the cement factory in Drogheda, 45 kilometres to the south. Perhaps it's because the silos are visible from a huge distance and demand explanation, or does it acknowledge the permanence of concrete in the modern landscape?
For real permanence, look instead at the ring dyke surrounding Gullion. Sixty million years! Before the glaciers of the last freeze thawed 12,000 years ago, the ice scraped the formation into its present shape, defining the ridges, gaps and valleys, opening corridors where today's roads run.
A raised section to the west is known as Ummeracam, an intriguing name that resolves into Iomaire Cam: a straightforward crooked ridge.
"Iomaire", a drill or ridge, was an eloquent concept in a potato culture. Tri iomaire treabhtha go deireadh an domhain . . . promises that the world will end when a ploughed ridge becomes invisible with the passage of time, and that process is repeated three times over. Ummeracam, formed all those years ago and still in its first decline, is a better bet than the lazy beds fading fast on other hillsides. Some of those are on their second round - pre-Famine expansion and decline, Emergency regeneration and decay - and it takes a slanting shaft of sun to reveal them now.
East towards Newry, the Dublin-Belfast motorway is clearly visible, a seam in the patched fabric of the land. Nearer the foot of the mountain, the still wintry fields show a darkened green like dirty canvas. There's a cluster of fresh roofs where a little suburb has been grafted onto a rural village. (Happens in the planning office: "Where did I put that estate? Had it in my hand a minute ago.")
The map says the place name is Meigh. In February we still haven't heard of it, nor do I recall it from any signpost ever seen while driving north. Most bilingual people have an ear for place names, echoes of the landscape.
On top of Slieve Gullion, map straining in the wind, I decode this one. Allowing for the sharpened vowels of northern speech, the root word must be magh (a plain). There is a plain down there, studded with unassuming farms.
We turn to descend, dropping from the bitter crest to a sheltered slope. Scores of sheep graze among the heather, hardy mountain ewes with ragged fleeces. They lift their heads, prepared to run from any threat. Bred to the heather and the slope, these sheep seem at home on Slieve Gullion. They will smell the snow before it comes and make their way downhill in the right direction. High on this cold mountain, living on the pickings of winter, they deserve respect. They strike me as survivors, the February sheep of south Armagh.