1. Blaenffynhonnau (South) enclosure is a partly plough-levelled cropmark concentric antenna enclosure presumably used for stock management and settlement, exploiting a narrowing point of the ridge, in later prehistory. It was discovered in 1989 during aerial reconnaissance by the Dyfed Archaeological Trust. The sub-circular inner enclosure is flattened on its upslope (north-west) side and encloses an area, c.80m NE-SW by 75. An antenna entrance opens on its south side, downslope, with a complex series of outer enclosures and ditches surrounding the site c.250m NW-SE by 200m.

(source: James 1990,fig 1A; plate 25a)

2. A field inspection by DAT on 13 January 2008 for the Defended Enclosures Project suggests that '... the enclosure is still visible as a slight earthwork on the ground. The inner circular enclosure of diameter c.70m is discernable as a low bank with an outer ditch, and is particularly visible on the northeast and northwest. The outer annexe defensive bank and ditch, and the ditched/banked track entrance on the south are just discernable on the ground, but have suffered from the effects of ploughing. The outer concentric annexe has a diameter of approximately 200m'. (DAT HER). This earthwork survival is confirmed on 2023 Welsh Government LiDAR which shows much of the inner enclosure earthwork surviving along with parts of the outer enclosure boundary. The site is currently bisected by a country road.

3. The cropmark enclosure, and an elaborate series of intergral ditches and boundaries, was recorded from the air during RCAHMW aerial reconnaissance on 26th June 2023 as a particularly clear parchmark in grass, revealing much new information. The new photography reveals an additional polygonal enclosure set some 80m downslope and to the southwest of the concentric enclosure; the new enclosure at SN 2562 1869 is broadly rectangular, aligned north-south, and measures 80m x 40m. The new photography also shows that the main concentric enclosure, which is sited on a summit ridge, is linked to a wider set of boundary ditches and/or well-worn braided trackways which climb the valleys to the southwest and northeast; the implication is that this enclosure, and perhaps others like it, sat at the heart of a wider, managed landscape of human and livestock movement and ownership.

T. Driver, RCAHMW, Oct 2018; updated June 2024