Archaeologists have uncovered what could be a 5,000-year-old ritual circle hidden beneath peat on a Scottish island, all without digging into the ground.
Using advanced geophysical scanning equipment, researchers from Historic Environment Scotland (HES) detected a ring of buried pits beneath Machrie Moor on the Isle of Arran. The circular arrangement, which may date back to the Neolithic or Bronze Age, had remained completely hidden below the surface.
The discovery was unexpected. Researchers had set out to test how well modern archaeological survey technology works in peat-covered landscapes. Instead, they found evidence of what could be a previously unknown ceremonial monument in one of Scotland's richest prehistoric landscapes.
"We are tremendously excited about this new discovery. "We know that there is a lot of archaeology yet to uncover at Machrie Moor, but the discovery of a new circle completely surpassed our expectations," said Dr Nick Hannon, Senior Heritage Recording Manager at Historic Environment Scotland.
A circle hidden beneath the peat
The newly detected feature consists of 12 circular pit-like anomalies arranged in a ring about 28 metres, or roughly 92 feet, across. Researchers identified the circle using geophysical survey equipment, which is pushed across the ground and detects subtle magnetic changes beneath the surface. The method allows archaeologists to map buried archaeological features without disturbing the soil or damaging ancient remains.
The pits are spaced about 6.5 metres apart. Two unusually wide gaps in the circle may indicate that two additional pits once existed but have since disappeared, raising the possibility that the monument originally contained 14 posts or standing stones. Survey data showed no evidence that the pits currently contain stone.
"There is no indication that any of these anomalies contain a stone" at this time, researchers noted in the survey report. That suggests the monument may have been built with timber posts, or that any standing stones were removed long ago.
Archaeologists scanned the ground to hunt out hidden historic clues
Scotland's prehistoric ceremonial landscape
Machrie Moor, on the west coast of Arran, is already one of Scotland's best-known prehistoric sites. The peat-covered landscape is home to standing stones, burial cairns and ceremonial monuments dating from about 3500 BC to 1500 BC. Archaeologists have identified six stone circles at the site since the 1980s. These are thought to have been built by Neolithic and Bronze Age farming communities and were used for ritual and ceremonial activities before some later became places for cremations and burials.
The newly discovered circle is believed to date from the same broad period, although researchers say further investigation will be needed before its age and purpose can be confirmed. "It is likely that the newly-discovered circle dates from a similar period as the other circles still standing," Historic Environment Scotland said.
Clues pointing to timber rather than stone
The discovery has also added to what researchers know about monuments already visible at Machrie Moor. At one site known as Circle 2, the survey revealed a ring of underground anomalies suggesting the monument may originally have contained 14 standing stones rather than the seven or eight reconstructed today. Earlier excavations at Machrie Moor found that several of the existing stone circles first began as timber circles. Around 2000 BC, many of those wooden posts were replaced with standing stones. Because no buried stones have been detected in the newly discovered monument, archaeologists believe it may represent another timber circle or one whose stones were removed over time.
An ancient circle believed to be from the Bronze Age at Machrie Moor in Scotland, looking northward.
Aligned with the midsummer sunrise
One feature links the newly found monument with the other ceremonial circles already known at Machrie Moor. The existing circles are aligned with a notch at the head of nearby Machrie Glen, where the midsummer sun would have risen. Archaeologists believe this orientation suggests astronomical observations may have formed part of ceremonies held there thousands of years ago.
Whether the newly discovered circle shared the same role remains uncertain, but its location within the ceremonial landscape makes it a strong possibility.
Finding the past without digging
The discovery highlights how archaeological technology is changing the way researchers explore historic sites. Rather than excavating large areas, scientists can now use non-invasive techniques to detect buried structures through subtle changes in the soil caused by ancient pits, postholes, stone features or other human activity.
Dr Hannon said these advances are helping archaeologists uncover new chapters of Scotland's past while leaving fragile sites undisturbed. "The tools we use to learn about what's underground are constantly developing, and we can learn more and more about our buried history without disturbing the earth and potentially damaging archaeological remains. "Discoveries like this one remind us why we do this work – to look after Scotland's heritage and uncover more of our past in the process."
The newly discovered circle has yet to be excavated, meaning many questions remain about exactly how it was built and used. For now, the buried monument has added another piece to the puzzle of Machrie Moor, a landscape that continues to reveal traces of the communities who gathered there more than five millennia ago.
