Thousands of coins removed from the Giant’s Causeway to protect basalt pillars; 10,000 coins wedged by tourists over the years extracted

More than 10,000 coins that visitors wedged into the rocks of Northern Ireland’s Giant’s Causeway have been extracted as conservation teams work to protect the World Heritage Site from further damage, Reuters reports. The coins came from visitors from the UK, Europe, the US, the Far East and other parts of the world.

Tourists have pushed or hammered coins into cracks and joints between the Causeway’s famous basalt columns as a way of leaving behind a token from their visit. But the National Trust, which cares for the site, says the practice has started damaging the rocks themselves.

Why are the coins damaging the rocks?

The problem begins when the coins corrode. The Giant’s Causeway sits on the Northern Ireland coast, where saltwater spray accelerates the breakdown of metal.

As the coins oxidise, they can expand to as much as three times their original thickness. That expansion pushes against the surrounding basalt and can cause the rock to fracture, flake and disintegrate. Corrosion also leaves copper, nickel and iron oxide stains across the stones.

A British Geological Survey report found that the coins were having both a physical and visual impact on the basalt. The National Trust said many modern UK coins contain multiple metals, including steel cores and metal coatings. When those different metals corrode at different rates, the layers separate and put further pressure on the surrounding rock.

The coastal environment makes the problem worse. Saltwater spray repeatedly soaks the coins, speeding up corrosion and increasing the pressure they exert inside the narrow cracks.

Specialists tested how to remove the coins

The National Trust worked with the Causeway Coast and Glens Heritage Trust and stone conservation specialists to develop a safe way to remove the coins without causing additional damage.

Teams first tested the removal process at 10 locations across the Causeway. The trial proved successful, allowing conservation workers to expand the effort across the site. The National Trust expects the wider removal project to cost more than £30,000.

The conservation work focuses on removing existing coins while also stopping visitors from adding more. The National Trust has urged tourists to avoid leaving objects behind and instead follow a "leave no trace" approach when visiting the landmark.

Dr Cliff Henry, National Trust Nature Engagement Officer at the North Coast, said visitors often form personal connections with the Giant’s Causeway and may want to leave a token behind. However, he warned that the coins damage the natural landscape and urged visitors to stop inserting them into the rocks.

Giant’s Causeway formed nearly 60 million years ago

The coin problem affects one of Northern Ireland’s most important geological sites. The Giant’s Causeway contains more than 40,000 basalt columns, which formed almost 60 million years ago when volcanic activity produced layers of basalt that later developed their distinctive shapes through cooling and cracking.

The site became Northern Ireland’s first UNESCO World Heritage Site in 1986. It also carries several other conservation designations, including Area of Special Scientific Interest, Special Area of Conservation and Natural Nature Reserve status.

The National Trust has cared for the Giant’s Causeway since 1961 and now wants visitors to help preserve the ancient basalt columns by leaving the rocks untouched.