In the dark waters of a remote Scottish loch, archaeologists have made a discovery that reshapes our understanding of prehistoric engineering. Using innovative shallow-water photogrammetry, researchers from the University of Southampton and the University of Reading have confirmed that the Loch Bhorgastail crannog - long believed to be a simple stone mound - was actually built upon a massive, sophisticated timber platform dating back over 5,000 years.
This remarkable find reveals that these artificial islands in the Outer Hebrides are significantly older than Stonehenge, pushing the timeline of complex construction in the region back to the Neolithic period. The revelation that timber, rather than stone, was the primary load-bearing element of these structures highlights the advanced capabilities of the communities that built them.
Aerial view of the Loch Bhorgastail crannog on the Isle of Lewis, Scotland. (F. Sturt/ Antiquity, CC-BY-SA 4.0)
A Wooden Foundation Beneath the Stone
For years, the Loch Bhorgastail crannog on the Isle of Lewis appeared from above to be a stone-built artificial island. However, the Islands of Stone project, funded by the Arts & Humanities Research Council, has overturned this assumption.
Dr. Stephanie Blankshein, an archaeologist at the University of Southampton, explained the significance of the find:
“When we actually started excavating is when we realized that it was actually this coherent, quite large timber structure that was under what you would see as the stone island today.”
The researchers discovered a 23-meter circular timber platform topped with brushwood, which formed the original base of the crannog. This foundational structure was laid down between 3500 and 3300 BC. Around 2,000 years later, during the Middle Bronze Age, another layer of brushwood and stone was added, followed by further activity during the Iron Age.
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The researchers found the remains of a large wooden platform under the crannog. (University of Southampton)
Overcoming Shallow Water Challenges
To fully understand the structure, the team had to map the crannog both above and below the waterline. This presented a significant challenge, as traditional photogrammetry is notoriously difficult in shallow water due to fine sediments, choppy conditions, and distorted light.
Professor Fraser Sturt, principal investigator and director of the Southampton Marine and Maritime Institute, noted that this problem is a "well-known frustration for archaeologists."
To overcome this, the team developed a new technique using two small, waterproof, low-light cameras mounted on a frame at a set distance apart. Maneuvered by a diver with centimeter-level accuracy, this setup allowed the researchers to create a high-resolution 3D digital model of the entire continuous structure. Their methodology was recently published in the journal Advances in Archaeological Practice.
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A Hub of Neolithic Activity
The Loch Bhorgastail crannog is not an isolated phenomenon. Hundreds of pieces of Neolithic pottery have been recovered from the loch bed surrounding the site, and a now-submerged stone causeway once connected the island to the shore.
Similar discoveries have been made across the Outer Hebrides. Of the estimated 170 crannogs in the island chain, several have yielded large collections of near-complete Neolithic vessels, suggesting systematic, possibly ritualistic, deposition into the water.
“While we still don’t know exactly why these islands were built, the resources and labor required to construct them suggests not only complex communities capable of such feats, but also the great significance of these sites,” Dr. Blankshein stated.
The new shallow-water photogrammetry technique will now be applied to other crannogs across the Outer Hebrides, promising to shed further light on these enigmatic "islands of stone" and the ancient people who built them.
Top image: Aerial view of the Loch Bhorgastail crannog on the Isle of Lewis, Scotland. Source: University of Southampton
By Gary Manners
References
Blankshein, S., Pedrotti, F., Sturt, F., & Garrow, D. 2026. At the Water’s Edge: Photogrammetry in Extreme Shallow-Water Environments. Advances in Archaeological Practice. Cambridge University Press. Available at: https://www.cambridge.org/core/journals/advances-in-archaeological-practice/article/at-the-waters-edge-photogrammetry-in-extreme-shallowwater-environments/D71DFA5DE1C9665218343DA3C3AAA55A
Cameron, L. 2026. Archaeologists reveal secrets of artificial island older than Stonehenge in Scottish loch. AOL. Available at: https://www.aol.com/articles/archaeologists-reveal-secrets-artificial-island-225518020.html
Ross, J. 2026. Stone Above, Timber Below — Scotland's 5,000-Year-Old Island Stood on Wood. Wood Central. Available at: https://woodcentral.com.au/scottish-stone-island-timber-platform-loch-bhorgastail-neolithic-crannog/
University of Southampton. 2026. Islands of Stone: Neolithic Crannogs in the Outer Hebrides. Available at: https://www.southampton.ac.uk/research/projects/islands-of-stone-neolithic-crannogs-in-the-outer-hebrides
