“Blacks Guide To Derbyshire 1881” mentions a stone in the centre of the circle, it wasn’t there at the time the guide was written, and Barnatt seems to think it may not have been there at all. The book also mentions the sizes of the barrows on the moor. The Eyam Moor Barrow was approx. 90ft in diameter and 35ft high. And one at Hayley’s Piece being 66ft wide and 36ft high.