Karst is a term used world-wide to describe the distinctive landforms that develop on rock types that are readily dissolved by water. In Ireland, limestone (composed of calcium carbonate) and to a lesser extent dolomite (calcium and magnesium carbonate) are by far the most widespread rocks that show karst features. There is also a small outcrop of a younger softer rock also made of calcium carbonate – the chalk of Co. Antrim – which shows some of the features characteristic of karstic terrains. In other parts of the world, highly soluble rocks such as gypsum (calcium sulphate) and halite (common salt or sodium chloride) are abundant and they also exhibit karstic landforms

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