A stone located to the south-west of Llyn Barfog (NPRN 402570) with a deep semi-circular impression resembling a horse's hoof-mark measuring rough 6in long and 4in deep (15.24cm x 10.16cm). The stone is marked in the landscape by an upright rectangular slate sign with the inscription `CARN MARCH ARTHUR? (`the stone of Arthur's horse?). The mark is supposed to have been left by King Arthur's horse when he drew the afanc (a water monster) from Llyn Barfog. Another tradition proposes that it was left by Arthur's horse as he leapt across the Dyfi from Merionethshire to Cardiganshire, landing is Cors Fochno.

(Sources: John Pughe, `Gwragedd Annwn.?The Dames of Elfen Land. A Legend of Llyn Barfog, Archaeologia Cambrensis, New Series: XV (July 1853), 201?05 (202); [Peredur], `Arthurian Localities?, Archaeologia Cambrensis, Fourth Series: V (January 1874), 88??90 (90); RCAHMW, Inventory of the Ancient Monuments of Wales and Monmouthshire: VI ? Country of Merioneth (London: His Majesty's Stationary Office, 1921), p. 175; Scott Lloyd, The Arthurian Place Names of Wales (Cardiff: University of Wales Press, 2017), pp. 193?4.
A.N. Coward, RCAHMW, 28.01.2019