What the first Ordnance Survey mappers recorded in 1839 as a neat circle roughly 26 metres across has, through successive revisions, transformed on the page into something more angular and roughly square. The ground itself has not moved, but the way people have read and drawn it clearly has.

The 1839 six-inch OS map shows the enclosure as circular, which would be consistent with a ringfort, the type of enclosed farmstead built across Ireland primarily between the early medieval period and around the twelfth century. Ringforts typically served as defended farmsteads, their earthen banks or stone walls enclosing a family's living and working space. At Coolroe, however, the circular outline already appeared compromised even on that earliest map, with field boundaries cutting across its southern and south-western edges. By the time the 25-inch OS revision was completed in 1900 to 1901, those same boundaries were being interpreted differently, recorded instead as a stream running south-eastward. On still later editions, the enclosure reads as a subsquare shape, approximately 20 metres north to south and 24 metres east to west. Whether this reflects genuine reinterpretation of what surveyors saw on the ground, or accumulated cartographic drift, is difficult to say without excavation.