What was once an earthen enclosure, a rath, has been so thoroughly absorbed into the agricultural landscape that no visible surface trace survives at all.

A rath, to give the term its context, was a roughly circular earthen bank enclosing a domestic settlement, typically dating from the early medieval period in Ireland, between roughly the fifth and twelfth centuries. Thousands were built across the country, and thousands have since been reduced by ploughing, grazing, and the incremental pressures of farming. The Ballyglass example measured approximately 29.3 metres east to west and 25 metres north to south, making it a modest but reasonably typical example of the type. When McCaffrey catalogued it in 1952, classifying it as an earthen fort and assigning it the reference number 142a, it was already described as extremely ruinous. The particular agent of its decline was a field fence, which had been built directly on top of the original bank, effectively cannibalising the monument and folding it into the ordinary infrastructure of the surrounding farmland. By the time of later surveys, nothing remained to be seen at ground level.