There was (is?) a further cairn uphill from here, to the NNE. If it still exists it's lost on the verge of a forestry track.
Carn Buarth Maen (SO0269104854)
Possible cairn, appearing as a low indistinct mound entirely covered with thick tussocks of grass; stone can be felt underneath. Edges most clearly marked at S and E; fade out on N and W. On the verge at the S of a forest ride, at the top of an E-facing slope. Dimensions: ?5.6m diameter; c 0.2m high
(1976) Now in a forestry plantation; nothing could be found (RCAHMW)
(1999) Cairn as noted on OS 6 inch 1st edition 1885 map. No visible presence; possibly destroyed by the FE or perhaps it is located within dense tree cover.
See directions for Mynydd Aberdare. Once you have parked up follow the edge of the trees south (along a rough track) and the Cairn is a just before you reach the electricity pylons.
Assuming you can spot it of course!
In a nutshell I couldn’t find it!
The ground here is undulating and covered in long, rough grass.
Good luck if you come looking. Even Coflein says it is ‘barely visible’.
‘This 14m diameter ring cairn is surrounded by a 0.2m high circular turf-covered stone bank with a gap in S side. The cairn is barely visible. Sited on S moorland slopes under rough grass’