On the 1947 to 1948 revision of the Ordnance Survey six-inch map, it appears as a hachured feature, the hatching technique surveyors used to suggest a depression or earthwork of some kind, the sort of mark that can send a researcher reaching for their boots in anticipation of something ancient. When someone did pull on those boots and visit in 1984, the feature turned out to be a disused sand quarry pit, most likely dug sometime after 1700.

That date matters in a particular bureaucratic and scholarly sense. Because the hollow post-dates AD 1700, it falls outside the period covered by the Archaeological Survey of Ireland, which concerns itself with earlier remains. The quarry is, in other words, too recent to be of official archaeological interest, and so it occupies a quiet liminal space: significant enough to be noted and visited, not significant enough to be formally studied. Sand quarrying of this kind was common in rural Ireland, where local pits provided material for construction and drainage work on farms and roads. The pit at Claggernagh is simply one such working, now grassed over and sinking back into the landscape it was once cut from.