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.
