The much altered round cairn at Pennant measures 18m in diameter and 1.5m high. It is suggested that the rectilinear structure constructed upon it was a powder store for the Nant Cwm Tywyll quarry (Nprn306586).

It is part of what is designated the 'Cwm Tywyll ritual complex' (SAM ME146: Nprn95526).

(source Os495card; SJ03SW9)
RCAHMW AP945109/48; 945173/46-9
J.Wiles 27.09.02