A ring-ditch, roughly twelve metres in external diameter, was identified through cropmarks, the faint but telling difference in crop colour and growth that appears over buried features during dry conditions. The ditch itself is only about a metre wide, and there is no detectable break or gap in it to suggest an entrance, which sets it slightly apart from what might be expected of a simple enclosure for the living.

Ring-ditches are generally understood to be the buried remnants of prehistoric funerary or ritual monuments, most often the circular quarry ditches that once surrounded a central burial mound, the mound itself long since ploughed away over centuries of agricultural use. The Piercetown example is not alone in its field; a second ring-ditch sits approximately 140 metres to the west-southwest. Together they occupy the southern part of a broad field, not far from another recorded enclosure to the south-east and within little more than a kilometre of the Irish Sea coastline at Holmpatrick. The site was compiled by Tom Condit and recorded on the national monuments database, with cropmark evidence drawn from Apple Maps satellite imagery captured in June 2018.

There is nothing to see at ground level, and the field remains agricultural land, so access is not a matter of turning up with a map and expecting a visible monument. The interest here is really in the method of discovery as much as the place itself. Cropmark sites like this one become most legible from the air during a dry summer, when moisture-starved crops over a buried ditch show a slightly different tone to the surrounding growth. For anyone curious about the landscape archaeology of the Dublin coastline, the national monuments record entry offers coordinates and the broader cluster of sites in the Piercetown and Holmpatrick area, which rewards patient browsing even if the land itself keeps its secrets firmly underground.