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Small coins are causing giant problems at one of Northern Ireland’s most famous natural sites.

Authorities are urging visitors to stop jamming pocket change between the basalt columns that make up the Giant’s Causeway, a national nature reserve and UNESCO World Heritage Site on the coast of the North Atlantic Ocean.

As the coins rust, they’re expanding to three times their original thickness. This is putting pressure on the surrounding basalt, which, in some instances, is causing the rocks to crack and crumble.

In addition, as the coins corrode, they’re leaving ugly streaks of copper, nickel and iron oxides on the rocks. They’re corroding rapidly because of the saltwater at the site.

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