Barrow I at Black Mixen measures 22m in diameter and 1.5m high, topped by an OS triangulation pillar. The pillar (NPRN 500031) stands at the centre and the flat top to the mound is uneven, pockmarked with erosion hollows. Most of the barrow is covered in heather but the erosion scars were exposed peat.

RCAHMW and Trysor, 11 August 2008