At a field near Skidoo in north County Dublin, the ground gives nothing away. No earthwork, no stone, no obvious depression or ridge betrays what lies beneath the soil. The feature only becomes legible when viewed from above, and even then only under the right conditions, when a dry summer causes buried archaeology to slow the growth of whatever crop is planted overhead, producing faint but telling colour differences across the field. What those differences trace is a ring-ditch, a circular or near-circular trench cut into the earth in prehistoric times, most commonly associated with burial or ritual activity.

The site was first recorded in June 1991, when Gillian Barrett identified the feature as a positive cropmark on an aerial photograph catalogued as GB91.DM.27. A positive cropmark occurs when buried features such as ditches, which retain more moisture than the surrounding subsoil, encourage lusher, taller, or darker-coloured vegetation directly above them, making the underlying shape readable from altitude in a way that ground-level observation simply cannot replicate. The ring-ditch at Skidoo sits on a low east-west ridge to the north of the Broadmeadow river, a position that would not have been without significance in the prehistoric landscape, where elevated ground near water frequently drew ceremonial or funerary use. The record was compiled by Geraldine Stout and later updated by Christine Baker.

Because the feature is not visible at ground level, a visit to the general area offers atmosphere and context rather than a legible monument. The low ridge north of the Broadmeadow river gives a sense of the subtle topography that seems to have appealed to those who created ring-ditches across the Irish landscape, and the river itself is worth observing as a likely ancient boundary and route. Anyone with a serious interest in cropmark archaeology would find the aerial photograph reference, GB91.DM.27, a useful starting point for archival research. The broader north Dublin landscape contains other recorded cropmarks and enclosures, and understanding Skidoo in relation to these neighbouring sites is probably the most rewarding way to approach what is, on the ground, an essentially invisible piece of the past.