At Trabolgan in County Cork, a semicircular earthwork once ran in an arc from south to north along the western side of the avenue leading into the estate. By the time anyone thought to record it properly, the depression that formed it had already been swallowed by tree planting, leaving no visible surface trace.

What we know of the feature comes from the Ordnance Survey six-inch map of 1935, which caught it just clearly enough to preserve its rough shape: a curved depression, suggestive of an enclosure of some kind, though its age and precise function remain unestablished. Earthworks of this general form in Cork can range from early medieval ringforts, which were typically circular or oval enclosures used as farmsteads, to later landscape features associated with post-medieval estates. The Trabolgan example sits on the edge of a landed estate, which complicates any straightforward reading; it could predate the formal avenue entirely, or it could be a remnant of earlier designed landscaping. Without excavation or more detailed survey, the question stays open.