Cefn Carnedd is an elongated enclosure, approximately 437m by 84m, with entrances on the north-eastern and south-western sides. It occupies the summit of Cefn Carnedd and is defined by scarps with triple banks and ditches to the north-west which form an additional 'barbican' enclosure, with an outer inturned entrance, before the north-eastern entry. A bank and ditch segregate an area, approximately 130m by 68m, at the south-western end. An original enclosure, approximately 235m fron north-east to south-west appears to have been extended north-eastwards, the original north-east ramparts being apparent on aerial photographs. This would suggest that the cross-bank is a later feature. Recent aerial photography has also identified more earthwork detail on the north side of the fort, including complex earthworks and a major north-west gateway which may have superceded the original ridge-top west gateway to the fort.
Occassional erosion scars in the ramparts of the fort yield little more than coarse shale rubble and earth, with little sign of any more massive stone work, or even formal revetment walling, although such remains may be buried deeper where the ramparts are well preserved. Erosion around the main west gate, caused by burrowing animals and livestock action, was most revealing; much of the shale rubble has a reddish hue and would appear to have been burnt. This was evident all around the west gate and could suggest a burning episode at one time.
The central ditch of the triple defences on the north-eastern side of the hillfort, evidently rock-cut although now in-filled, was waterlogged on the visit, with standing water and boggy ground present in many places. This would suggest excellent paleoenvrionmental potential of any buried deposits. In addition, the north-eastern defences as they approach the main east gateway incorporate a prominent spring which is still active
Two body sherds of VCP (Very Coarse Pottery), containers of which were used to transport salt from the midlands plain in prehistory, were discovered during fieldwalking on the fort in the 1970s
A possible sling shot was identified outside the fort to the west. The smooth, oval, river cobble measuring approximately 6.5 cm x 5 cm was found on the surface of the grass at SO 0131 8985, where it had rolled down from an eroded farm track which passes through a gate in the modern wire fence. An inspection of the eroded track showed that all the stone present was of natural broken shale rubble in mud, there being no sign of imported stone cobbles being used for surfacing. The possible sling shot was covered with the same mud. Its position some 140m west of the main west gate of the fort would accord well with a genuine sling shot which had been dispatched from the fort defences, and come to rest on the slopes outside the fort.