The County Durham Sites & Monuments Register lists this as an iron age hillfort:
"On the plateau here we find traces of entrenchments, but in so broken a condition that it is difficult to say more than that a fortress of considerable strength once existed' (Co. Durham. VCH, 1905. vol.1, p. 348). One side of the site is described by Bailey (Antiq. Repertory, 1780, iii) as c.140yds long. "The site of this earthwork occurs on land which has a rather prominent slope from south to north. It is broken by rigg and furrow ploughing and mining subsidence, and the only traces which may fairly have a connection with the site are on the west side, consisting of a ditch 5m wide and 1m deep with a few stones visible in the inner bank. The ditch is much deeper than the furrows of the ploughing and extends from NZ15422826 to NZ15432855. There is no evidence of internal occupation" (NZ12NE11, Ordnance Survey, 1954). Destroyed by opencast mining (NZ12NE11, Ordnance Survey, 1972)."