Lasers Help Scientists Spot 900 New Archaeological Sites on Scotland’s Isle of Arran

The tech allowed researchers to conduct a ‘rapid archaeological survey, over weeks rather than months or years’

Medieval roundhouse identified using laser scans of the Isle of Arran. Historic Environment Scotland

The Isle of Arran located off Scotland’s west coast is one of the most archaeologically rich sites in all of Great Britain. The island is home to some of the British Isles’ most impressive prehistoric sites, featuring Neolithic stone circles and standing stones, ancient burial grounds and cairns, and the remains of Stone Age and Bronze Age homes.

Now, a recent airborne laser scan of the area has found 900 previously unknown archaeological sites on Arran, promising to rewrite the 6,000-year human history of the island, the BBC reports.

Some of the newly spotted sites include medieval farmsteads, prehistoric settlements and a rare cursus monument, which is a ceremonial ditch with parallel earthworks on either side that is not normally found on Scotland’s west coast, according to a project description from Historic Environment Scotland, the agency that conducted the survey.

“This survey has shown us that there are double the number of ancient monuments on Arran than we previously knew about,” Dave Cowley, rapid archaeological mapping manager at Historic Environment Scotland, tells the BBC.

From 2012 to 2014, a private company called Fugro collected airborne laser scans, or LiDAR, of the island made for the Scottish government. During 2017 and 2018, the team used that previously collected data to create various digital visualizations and maps of the island. Based on those images, the team identified possible archaeological sites.

During the project's second stage, six team members took to the field for six weeks in early 2018 to check out the most promising archaeological targets. In total, they visited 500 new sites and found 152 others while walking in areas that were not seen on the aerial maps. In total, the team identified 898 previously unknown sites. About 100 sites are prehistoric, and almost 200 are shieling hut sites, or temporary shelters used in the summer months to tend grazing livestock and to make dairy products, which were popular in the 12th to 17th centuries.

“This new 3D technology has allowed us to undertake a rapid archaeological survey, over weeks rather than months or years, and allowed us to discover sites that might even have been impossible to find otherwise,” Cowley tells the BBC. “We have been able to see how densely settled parts of Arran were, and the medieval and post-medieval shieling sites that were discovered have told us how upland areas were used by shepherds.”

The Historic Environment Scotland has used LiDAR technology to hunt for archaeological sites before, too. In 2017, the agency commissioned laser scans of Holyrood Park in Edinburgh, a craggy city park with evidence of human habitation dating back 5,000 years. Those scans revealed previously unknown banks and enclosures and revealed details of an Iron Age fort and settlement near a parking ramp. It also helped park managers see where footpaths and other visitor infrastructure was damaging archaeological sites.

Laser scans aren’t the only technology being used to unlock Scotland's past either. Earlier this year, the National Trust for Scotland commissioned a mapping company to use a drone to take ultra-high-resolution images of Canna and Sanday Islands in Scotland’s Inner Hebrides Islands. That work resulted in an incredibly detailed map that revealed archaeological features stretching back thousands of years.

Historic Environment Scotland now says it hopes to do more LiDAR scans, which are faster and cheaper than conducting on-the-ground surveys.

“We are exploring the benefits of new technology and new datasets to record Scotland’s historic environment and inform our knowledge of the past. As a result, we are enriching the information through which we tell Scotland’s story,” Cowley tells the BBC. “And Arran is just a first step. As this technology become more widely available, we expect to find tens of thousands more ancient sites across the rest of Scotland – working at a pace that was unimaginable a few years ago.”

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