Pentre Ifan and the Solstice: Ancient Welsh Megaliths as Cosmic Clocks
Pentre Ifan and the Solstice: Ancient Welsh Megaliths as Cosmic Clocks
Stand beneath the capstone of Pentre Ifan on a December afternoon and something peculiar happens to your sense of time. The stone above you -- five metres of igneous rock balanced on three tapered points, an estimated sixteen tonnes suspended two and a half metres off the ground -- has been holding that position for roughly five and a half thousand years. The Preseli Hills rise behind it. The Nevern Valley opens out below. And if independent researcher Robin Heath is correct, the entire arrangement was deliberately oriented so that the midwinter solstice sun would set along its axis around 3500 BCE.
Whether the builders intended that alignment or not -- and this remains a genuine debate among archaeologists -- the question it raises is fascinating. Did the Neolithic communities of west Wales understand the sky well enough to encode solar events into stone? The evidence across the Welsh landscape suggests the answer is more complex, and more impressive, than most people realise.
A Floating Stone on a Pembrokeshire Hillside
Pentre Ifan sits in the parish of Nevern, Pembrokeshire, about three miles east of Newport. The name translates from Welsh as "Ifan's village," though nobody knows who Ifan was or when the name stuck. What we do know is that the dolmen dates to approximately 3500 BCE and was among the very first monuments in Wales to receive legal protection, scheduled under the Ancient Monuments Protection Act of 1882. Today it is maintained by Cadw, the Welsh Government's historic environment service.
The monument consists of seven principal stones. Three slender uprights support the massive capstone, which is roughly five metres long, nearly two and a half metres wide, and about a metre thick. Two additional portal stones form an entrance, and a sixth stone appears to block the doorway. The whole structure was once covered by an earthen mound estimated at around thirty metres in length, though excavations conducted by William Grimes in 1936-37 and 1958-59 found very little inside: some flint flakes and fragments of pottery. No bones.
That absence of human remains matters. It fed into a significant reappraisal of the monument's purpose. In 2014, archaeologists Vicki Cummings and Colin Richards proposed that dolmens like Pentre Ifan were never designed to be burial chambers at all. They argued that the capstone -- deliberately shaped on its underside, perched on the narrowest points of slender uprights -- was meant to appear as though it were floating. The visual effect, they contended, was the entire point. The stones were never supposed to be hidden under a mound. What we see today may in fact be what the builders always intended people to see: a massive, impossible-looking act of engineering, a statement of communal power and technical mastery.
The Solstice Question
This is where things get interesting for anyone drawn to the relationship between ancient monuments and celestial events.
Robin Heath, a researcher and surveyor who spent decades mapping the prehistoric monuments of west Wales, proposed in his book Bluestone Magic (2010) that Pentre Ifan may have been intentionally aligned upon the midwinter solstice sunset. Heath identified a sightline involving a large recumbent stone at nearby Corlan Samson, which bears two distinctive perforations and appears to point toward the dolmen. When this line is extended beyond Pentre Ifan, it corresponds with an outcrop on the far flank of Carn Meibion Owen on the distant horizon.
It is a provocative idea, and not everyone in the archaeological community accepts it. The difficulty with solstice alignments is that they can be devilishly hard to prove. As some sceptics have pointed out, if you build a stone structure on a hillside and look toward the horizon, some of the stones are almost bound to line up with something astronomical at some point in the year. The challenge lies in distinguishing genuine intent from coincidence.
Still, when you consider Pentre Ifan in the context of the wider Preseli landscape -- a region dense with Neolithic monuments, stone rows, standing pairs, and stone circles -- the idea that its builders were attuned to the movements of the sun and moon starts to feel less speculative.
Gors Fawr: A Stone Circle and Its Outliers
About five miles south of Pentre Ifan, in boggy moorland near the village of Mynachlog-ddu, sits Gors Fawr stone circle. The name means "great marsh" in Welsh, which is an accurate description of the terrain. Sixteen low stones -- roughly half of them bluestone, the rest local glacial erratics -- form a slightly egg-shaped ring approximately twenty-two metres across.
The circle alone might not say much about astronomical intent. But about 130 metres to the north-north-east stand two taller outlying stones, sometimes called the Gors Fawr Outliers. One of these, locally known as the "Dreaming Stone," reportedly has a ledge-like shape that invites sitting. According to antiquarian Aubrey Burl, the pair are set on a north-east/south-west axis, and their alignment to the north-east looks toward the midsummer solstice sunrise.
More recently, a 2024 paper published in the Journal of Skyscape Archaeology reported observations of shadow-casting phenomena at Gors Fawr, noting that the circle appears to have multiple gnomons -- essentially sundial-like stone elements -- positioned on its circumference, producing complex shadow patterns concentrated at the solstices and equinoxes. The winter solstice showed particular focus.
Whether the builders of Gors Fawr deliberately engineered these effects or whether the geometry emerges naturally from the placement of stones in relation to the sun is an open question. But the pattern keeps recurring across the Preseli landscape: monuments and sightlines that seem to acknowledge turning points in the solar year.
Bryn Celli Ddu: The Proof on Anglesey
If the astronomical alignments of Pembrokeshire's megaliths remain debatable, the case is considerably stronger at Bryn Celli Ddu on Anglesey, about 130 miles to the north.
The name translates as "the mound in the dark grove." Built around 3000 BCE on the remains of an earlier stone circle and henge, Bryn Celli Ddu is a passage tomb with an 8.4-metre stone-lined corridor leading to a central burial chamber. And its passage is aligned so that at dawn on the summer solstice, sunlight penetrates the full length of the corridor and illuminates the back of the chamber.
This alignment was first proposed in 1906 by Sir Norman Lockyer, a pioneer of what would later become archaeoastronomy. Lockyer's claim was dismissed at the time, and it languished for nearly a century until archaeologist Steve Burrow, curator of Neolithic archaeology at the National Museum of Wales, decided to test it. It took him two visits -- overcast skies thwarted the first attempt -- but in 2005, Burrow confirmed that Lockyer had been right. At dawn around the longest day of the year, a blade of sunlight travels down the passage and lights up the chamber.
The precision is telling. Bryn Celli Ddu's passage is not merely "roughly" oriented to the east. The alignment was tight enough that Burrow has argued it was deliberately carried over from the orientation of the original henge, and later modifications to the passage appear to have been made specifically to sharpen the effect. The builders were not just aware of the solstice sunrise; they were engineering around it.
This places Bryn Celli Ddu in remarkable company. Its counterparts include Newgrange in Ireland's Boyne Valley, where a specially constructed "roof box" above the entrance channels the winter solstice sunrise along a nineteen-metre passage to illuminate the central chamber for seventeen minutes, and Maeshowe on Orkney, which captures the midwinter sunset. These are not vague gestures at the sky. They are calculated feats of alignment built into the architecture of monuments that took years, possibly decades, to construct.
The Preseli Connection
There is one more thread worth pulling, and it ties these Welsh sites together in a way that few other landscapes can match.
The Preseli Hills -- the ridge that forms the backdrop to Pentre Ifan, that looms above Gors Fawr, that gave the region its prehistoric significance -- are the source of Stonehenge's bluestones. Geologists have known this since the 1920s, when petrologist Herbert Henry Thomas first matched the bluestone at Stonehenge to outcrops in these hills. In 2019, a UCL-led team pinpointed the exact quarries: Carn Goedog for the spotted dolerite and Craig Rhos-y-felin for rhyolite, both on the northern slopes of the Preseli ridge. Charcoal found at the quarry sites dated the extraction activity to around 3000 BCE.
Professor Mike Parker Pearson of UCL's Institute of Archaeology noted that the quarrying dates precede the accepted construction date of Stonehenge by several centuries. His team has proposed that the stones may first have been erected in a local monument somewhere in the Preseli area, then later dismantled and transported 180 miles east to Salisbury Plain. If true, the Preseli Hills were not merely a quarry but a sacred landscape in their own right -- one where astronomical awareness was woven into the placement of stones long before those stones made their famous journey.
Research has also shown that many of the bluestones have unusual acoustic properties. When struck, they ring like bells. Whether this was the reason they were chosen remains unknown, but it suggests the Neolithic builders of this region were paying attention to the physical properties of stone in ways we are only beginning to appreciate.
What the Stars Meant and What They Might Still Mean
From the perspective of psychological astrology -- the discipline Martyn Shrewsbury practises here at the Wilfred Hazelwood Clinic -- the enduring fascination with these sites is not really about archaeology at all. It is about what the monuments reveal of the human impulse to find meaning in the relationship between earth and sky.
The solstices mark threshold moments. The winter solstice is the shortest day, the point at which darkness has reached its fullest extent and the light begins its return. The summer solstice is its mirror: the peak of light before the slow decline toward winter. For those who work with astrological symbolism, these are not just dates on a calendar. They represent the psychological experience of transition, renewal, and the cyclical nature of growth.
Carl Jung, whose analytical psychology underpins much of what we do at the clinic, wrote extensively about the archetype of death and rebirth. He saw it recurring across cultures, myths, and individual psyches. The idea that Neolithic communities in Wales built stone monuments to mark precisely these turning points -- the death of the old sun, the birth of the new -- resonates with something deep in the Jungian understanding of the collective unconscious. These were not primitive people making crude gestures at the sky. They were engaging with the same archetypal patterns that continue to shape human experience thousands of years later.
Whether you visit Pentre Ifan for its archaeology, its atmosphere, or its possible astronomical alignments, the experience is oddly personal. The stones do not explain themselves. They sit quietly on their hillside, framing the Preseli ridge against the sky, and they let you bring whatever meaning you carry. In that sense, they work not unlike astrology itself: a framework that does not dictate, but that offers a lens through which the rhythms of life can be observed, considered, and perhaps better understood.
If you are interested in exploring how the cycles of the planets and the symbolism of the solstices relate to your own psychological landscape, Martyn Shrewsbury offers consultations in psychological astrology at the Wilfred Hazelwood Astrology and Psychology Clinic. Get in touch to find out more.
