A rectilinear mound, 6m northwest-southeast by 5m and up to 1m high. It was formed of reddish soil with some stone, and covered with grass when recorded in September 2007. It is thought to be related to the construction of the Grwyne Fawr reservoir in the early 20th century but its purpose is unknown. J.J.Hall, Trysor, 27 September 2007