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A ring cairn (also correctly termed a ring bank enclosure, but sometimes wrongly described as a ring barrow) is a circular or slightly oval, ring-shaped, low (maximum 0.5 metres high) embankment, several metres wide and from 8 to 20 metres in diameter. It is made of stone and earth and was originally empty in the centre. In several cases the middle of the ring was later used (at Hound Tor, for example, there is a stone cist in the centre). The low profile of these cairns is not always possible to make out without conducting excavations.