A magnetic gradiometer survey, a technique that detects subtle variations in the soil's magnetic properties caused by buried features such as ditches and drains, revealed a field system covering approximately 2.5 hectares, or around seven acres, spreading northward and eastward from a nearby moated site. Moated sites are a characteristic feature of medieval Ireland, typically comprising a raised platform or enclosure surrounded by a water-filled ditch, most often associated with Anglo-Norman manorial settlement from the thirteenth and fourteenth centuries. This field system appears to have been directly attached to one such enclosure.

What the survey mapped is a careful, organised agricultural layout. The fields are generally rectangular, ranging from roughly 30 by 20 metres up to 60 by 50 metres, each defined by single ditches and internally marked by cultivation ridges, the narrow parallel mounds thrown up by repeated ploughing that are a common sign of sustained medieval tillage. Critically, these smaller, ditch-bounded fields do not stand in isolation. Further to the north and east, they give way to larger rectangular enclosures bounded by double ditches, and those larger fields appear on the 1839 edition of the Ordnance Survey six-inch map, suggesting a continuity of agricultural organisation that stretched from the medieval period well into the nineteenth century. The Corock River, a north-south stream, runs approximately 200 metres to the east at its nearest point, close enough to have influenced drainage patterns across the whole area.

The field system at Rosspile is not the kind of place that announces itself. There is nothing visible above ground to mark the medieval ditches or the cultivation ridges that the gradiometer detected. Its significance lies precisely in that invisibility, and in what the survey data suggests about how systematically the land around a medieval moated settlement was organised, managed, and then quietly absorbed into later farming practice without the underlying logic ever quite disappearing.