This quarrying into a natural outcrop on a ridge on Merthyr Common has been mistaken in the past for a cairn. The natural stone has fractured and produced a feature like a cairn which has then had at least four small quarry pits When seen in 1960 by the RCAHMW the "cairn" measured 5.8m in diameter and 0.6m high, and was turf-covered with large slabs around it.

David eighton, RCAHMW, 20 July 2005