Scientists Uncover New Clues About the Volcanic Origins of the Giant’s Causeway, an Iconic Geologic Structure in Northern Ireland

The UNESCO World Heritage Site, which features 40,000 near-perfect hexagonal columns, formed roughly 60 million years ago during a period of intense volcanic activity

Sarah Kuta | Daily Correspondent

June 16, 2026 5:32 p.m.

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As the legend goes, an Irish giant called Finn McCool wanted to cross the Irish Sea to face off with his Scottish rival, Benandonner, so he built a path across the water. However, after their confrontation, Benandonner destroyed most of the route, leaving behind only the 40,000 near-perfect hexagonal columns on the coast of Northern Ireland known as Giant’s Causeway.

In reality, the Giant’s Causeway didn’t form because of an epic clash between two hulking foes. Instead, scientists say the iconic landmark formed roughly 60 million years ago after piping hot lava flowed out of fissures in the earth. The molten rock cracked as it cooled, creating the straight-sided, interlocking columns still visible at the beloved site today.

Now, researchers have linked the formation of the Giant’s Causeway with a “globally significant volcanic event” that produced geologic formations in modern-day Iceland, Greenland, Scotland, the Faroe Islands and Northern Ireland, according to a statement from the British Geological Survey.

Scientists long thought this event formed volcanic rocks—including those that make up the Giant’s Causeway—over a span of about 13.5 million years. But they’ve now determined that the rocks formed much more quickly, in just 5.5 million years, they report in a new paper published in March in the journal Geology.

“While we knew generally the volcanic story of the Giant’s Causeway, what we can now do is link its timing to other volcanic systems in the region at an unprecedented level,” study co-author Simon Tapster, a geochronologist with the British Geological Survey, tells the Guardian’s Donna Ferguson.

The new study focuses on the North Atlantic Igneous Province, a massive geologic region created during a period of intense volcanic activity that took place roughly 60 million years ago. The province eventually broke apart due to geologic and tectonic forces, but its unique basalt lava signature lives on in a “tapestry of volcanic rocks” found throughout the North Atlantic today, Tapster tells the Guardian.

Scientists used geochemical analyses and airborne magnetic surveys to more precisely date the volcanic activity that formed the rocks and other geological formations found across Northern Ireland, including the Giant’s Causeway, the Mourne Mountains and Slieve Gullion mountain. They’ve now determined that this volcanic activity was far more concentrated—and the geological processes it triggered occurred more rapidly—than they previously thought.

“These findings have completely changed how we understand Northern Ireland’s place in the wider North Atlantic volcanic story,” lead author Mark Cooper, chief geologist for the Geological Survey of Northern Ireland, says in the statement.

Located on the north coast of Northern Ireland, about 60 miles from Belfast, the Giant’s Causeway is one of the country’s most famous natural sites. In 2025, the UNESCO World Heritage Site attracted more than 678,000 visitors from around the world, who came to see the stones, admire the native seabirds and explore the miles of coastal footpaths.

The basalt columns that make up the Giant’s Causeway have endured tens of millions of years of natural forces. Recently, however, they’ve come under pressure from a far more modern force: tourists.

Visitors have been shoving metal coins in crevices within the basalt columns. Over time, the pocket change tarnishes via oxidation and expands, which puts pressure on the surrounding basalt. In some cases, the coins have caused the rocks to crack and crumble. The National Trust, the conservation charity that manages the site, and other collaborators have been working to remove the damaging coins while also raising awareness about the harmful practice.

After a successful trial removal in February 2024, conservationists surveyed the site and created a detailed map of the most affected areas in November 2025. They also dislodged coins from several test locations.

The project continued this spring, with a team from ‘The Rock’ Stone Masonry using a variety of tools to gingerly extract the coins. They likely won’t be able to remove all the coins, especially those that have become heavily corroded after years of exposure to saltwater at the site.

“Once they’re jacked up, the stones can’t come back down again,” says Nathan Morrow, owner of ‘The Rock’ Stone Masonry, in a video created by the National Trust and other partners. “So, we’re going to be very, very careful on removal of the heavily oxidized coins. … Very, very simply, six coins can lift six [metric] tons easily.”

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Sarah Kuta is a writer and editor based in Longmont, Colorado. She covers history, science, travel, food and beverage, sustainability, economics and other topics.