1. Royal Commission aerial reconnaissance on 10th July 2018 revealed parchmarks south of Fach Farm of what appeared to be a bivallate square enclosure with rounded corners some 70m across, possibly representing a later prehistoric enclosure. The enclosure appears to be encircled by an outer defensive ditch, similar to a probable Roman fortlet surveyed by GAT at Cemlyn on north Anglesey in 2014 (NPRN 423452). The enclosure occupies a locally prominent knoll below the summit of a south-east facing ridge at around 45m O.D., sited against an escarpment edge on the east side, with good views of Abersoch beach beyond. A field visit on 17th August 2018 during filming of 'Hidden Britain by Drone' for Channel 4, which confirmed an earthwork approx. 1.5m in height represent the potential rampart survives against the escarpment edge on the east side. Discovered during the 2018 drought.

Recorded during baseline aerial reconnaissance survey for the CHERISH Project. ? Crown: CHERISH PROJECT 2018. Produced with EU funds through the Ireland Wales Co-operation Programme 2014-2020. All material made freely available through the Open Government Licence.

T. Driver, RCAHMW, 14-09-18

2. New geophysical (magnetometry) survey was carried out across the cropmark in March 2019 for the CHERISH Project by SUMO Survey Services: 'A multi-vallate enclosure has been detected in the location of the parch marks identified in the aerial reconnaissance survey carried out by the RCAHMW (2019). The enclosure comprises three concentric ditches, with the outer ditch measuring some 115m in diameter, and the smallest inner ditch approximately 50m across. The enclosure was originally thought to be a "bivallate square enclosure with rounded corners, comparable to that of a Roman Fortlet (GAT 37976) on Anglesey? (RCAHMW 2019); however, the results indicate that the Fach Farm enclosure is in fact circular in form and comprises three defensive ditches as opposed to two. It is arguable that the smallest, internal ditch, has a sub-rectangular form similar to that at Cemlyn; however, few other similarities can be drawn between the Cemlyn site and the enclosure at Fach Farm (Plates 1 & 2 below).

The geophysical survey at Fach Farm, Abersoch, has identified a multi-vallate defended settlement, in contrast to an earlier assessment of the site from aerial reconnaissance (RCAHMW) when it was thought to be associated with a Roman fortlet. Comparisons had been drawn between Fach Farm and another Roman fortlet at Cemlyn (GAT 2015), but this now seems unlikely. This geophysical survey has revealed three concentric defensive ditches, some 115m across at its widest point, and as such it is probable that the site has origins earlier than the Roman period, though the exact date of the settlement is difficult to ascertain.
Within the area surrounding the enclosure, a number of additional linear and discrete anomalies have been identified, including a sub-rectangular enclosure, potential ring-ditches and trackways. The exact origin of these responses remains less clear, and it is feasible that the ditches relate to a peripheral field system. The remaining linear anomalies identified in the survey could have archaeological, natural or agricultural origins. Evidence for modern ploughing is visible across the site, along with a couple of areas of natural magnetic variation and an underground service.

Extract from Davies, R. 2019. Geophysical Survey Report 14719: CHERISH Ireland-Wales Project - Fach Farm, Abersoch, Gwynedd. SUMO Services. Unpublished.