Giant's Causeway visitors urged not to jam coins into rocks

Catherine MorrisonBBC News NIGetty ImagesHundreds of thousands of tourists and locals visit the Giant's Causeway each yearThe Giant's Causeway has faced many threats to its survival, from mythical fights between giants to coastal erosion and rising sea levels. Now there's a new problem.At first, you don't notice them but as soon as you see one, you start to see them everywhere - hundreds of them, in every fissure…