Royal Commission aerial reconnaissance during the 2018 drought, on 4th July 2018, discovered multiple cropmarks in pasture surrounding the natural lake of Maes-llyn.

Maes-llyn is a small, oval natural lake around 170m across, truncated on its south-eastern side by the former line of the nineteenth century railway and the modern road. Parchmarks recorded during drought conditions highlighted a number of cropmark fearures; (1) a rectangular ditched enclosure on the northern shore of the lake at SN 692 629, measuring 47m x 30m, with a cluster of internal pits. (2) In the main field on the north-west side of the lake are further circular pits, confused by more diffuse circular darker rings likely to be of geological origin. (3) On the north side of the farm buildings of Maes-llyn are cropmarks of two parallel ditches running east-west for c. 175m, sited 36m apart. Although these ditches could remnants of a medieval strip field, they appear to be purposefully constructed and potentially part of a larger structure or enclosure, now obscured by the farm. (4) A small concentric ring ditch immediately west of the farm at SN 6903 6295 may be a prehistoric burial monument or a more recent agricultural mark. It is difficult to be sure on the basis of photographic evidence alone.

It is highly likely that the small number of natural lowland lakes along the fringes of the Teifi valley provided a focus for later prehistoric communities who occupied the many hillforts in this part of the county. Maes-llyn lake occupies a distinct lowland spur projecting into the Cors Caron wetland below a hillfringe zone with three or four Iron Age hillforts. The cropmarks noted around Maes-llyn are unusual, and similar markings have not been noted at other lakes in Ceredigion. They are certainly suggestive of a potential ritual or ceremonial focus here in prehistory.

T. Driver, RCAHMW, 2019.