Due to the mountain's perfectly triangular profile and its prominence and domination of the skyline in the region, Croagh Patrick would have formed a natural landmark long before the arrival here of man." This passing observation, in a new publication on the archaeology and landscape of the Reek, challenges the philosopher in us all: could a mountain be a landmark when there was no one around to see it? But archaeologist Leo Morahan connects with an important thread in our reverence for mountains: an awe of their timeless continuity. When deep ecologists urge us to practise "thinking like a mountain", they reach back to an animistic bond with Earth that has power to move us still.

Archaeologists have earned a greater right than most to speculate on the spiritual significance of Croagh Patrick. In the summer months of 1994 and 1995, an excavation team climbed the 700-odd metres to its summit every day, returning each evening after a full day's work. Later, 10 F=C1S workers were mobilised to help in a wider, two-year exploration of the mountain and its surroundings.

This has now doubled the known number of monuments in a richly-settled coastal landscape (some 80 early Christian ringforts, for example, occupied the high ground of drumlin hills and ridges). But on the mountain itself, the most intriguing evidence is for sacred ritual and fortification of the summit even before the 1,500 years of Christian pilgrimage.

The peak has had a succession of church buildings, and the first season's excavations, directed by Gerry Walsh, uncovered the remains of an early Christian oratory where St Patrick was supposed to have built his church. But enclosing the summit, and its remains of monastic huts, are the scattered rocks of a prehistoric rampart. The impressive three-metre-high cairns on the mountain's shoulders, used by many pilgrims as prayerful stations, are also prehistoric.

The most potent evocation of the Reek's pagan significance remains, perhaps, the "rolling sun spectacle", first observed and recorded by a Westport local historian, Gerry Bracken, more than a decade ago. His multiple-exposure photograph has become a dramatic icon of astronomical archaeology, and duly appears in the new book.

The Boheh stone, which juts up in a farmyard about six kilometres east of the mountain, is wonderfully decorated with "cup and ring" motifs. This art dates from the era of megalithic tombs, and the rock may have marked an important stop on the westward route to Croagh Patrick from the sacred, pre-Christian landscape at Rathcroghan in Co Roscommon.

Gerry Bracken, seeking significant alignments, took to visiting the rock at sunset on the summer and winter solstices and then at other, more frequent intervals. He was convinced there must be a date when the sun, in declining, hit the mountain peak spot on.

On April 16th, 1991, cycling away up the road after yet another "miss" by the setting sun, he happened to glance back. From his new, chance, position 200 metres from the stone, the orb of the sun was resting on the right-hand slope of the mountain. As he watched, transfixed, it continued to "roll" like a blazing chariot wheel, gradually and precisely following the edge of the mountain's silhouette.

At the stone itself, April 18th turns out to be the date in spring when the spectacle is most exact, and August 24th is its summer counterpart - dates which seem at least plausible for the planting and harvesting of crops.

Gerry Bracken gained the interest, and then the positive excitement, of Prof Patrick Wayman, director of Dunsink Observatory in Dublin and professor of astronomy at Trinity College, Dublin. Together they wrote a scholarly paper, "A Neolithic or Bronze-Age Alignment for Croagh Patrick". The Royal Irish Academy, however, refused to be impressed, returning it to the authors without comment, like some off-the-wall treatise on ley lines or crop circles. Now, however, the rolling sun has been given its proper place in the story of the Reek's archaeology.

Leo Morahan records another suggestion about the Boheh stone: that its carvings were created by early prospectors for metals. The gold now known to be locked up in Croagh Patrick's quartz veins is more than hinted at in the original Irish of the Owenwee, the Yellow River, which rises on the mountain, and traces of gold are still found in this and other streams to the west. An important pagan idol of gold was referred to in about the 10th century as Cromm Cruaich.

All this helps to nourish Morahan's picture of a "lofty power-base" established in the summit hill-fort of Croagh Patrick, which commanded control of all the local natural resources as well as all the rituals of communion with the gods. Where does this leave St Patrick? The traditional view is that he spent 40 days and nights on the mountain in 441AD, determined to appease and convert whatever spiritual power resided there. But Leo Morahan points to difficulties in the saint's history, quoting Donncha O Corrain's recent reference to "the expansion of his cult (a carefully crafted undertaking of the clergy of Armagh)".

Indeed, the "snakes" that myth insists were expelled by Patrick could actually have been a metaphor for the pagan druids and the symbols of their rival religion.

The traditional night-time ascent of Reek on the last Sunday of July was switched to safer daytime climbs in 1974 and the loss of dramatic atmosphere has reduced the number of pilgrims. But the numbers visiting the mountain throughout the year - estimated at up to 100,000 -mean it remains Ireland's foremost holy mountain, as appealing to ecological devotees of Gaia as to followers of a Christian saint.