That, in a sense, is what makes this spot worth knowing about. An earthwork that once rose ten feet above the surrounding ground, with a platform some 63 feet across at its base, was gradually eaten away by quarrying until, by 1937, it had been entirely removed. The place is recorded, mapped, and described in some detail, and then it simply ceases to exist.

When Herbert Gillman wrote about it in 1897, the mound was already in trouble. Quarrying had by that point removed roughly a third of the platform, and during that work a souterrain was uncovered, a type of underground stone-lined passage associated with early medieval settlement, often used for storage or refuge. Gillman noted that the earthwork was known locally by two names: "the mote", suggesting that people associated it with the Norman motte-and-bailey tradition of raised earthwork fortifications, and "a lios", the Irish term for a ringfort. Whether it was one, the other, or something older is a question the gravel ridge can no longer answer. It appeared on the 1842 Ordnance Survey six-inch map as a hachured circular enclosure, indicating that cartographers of that period considered it significant enough to record carefully. By the time P. J. Hartnett noted its complete disappearance in 1939, the archaeology was gone along with the spoil.

There is no visible surface trace remaining at Knockanenagark. The site exists now only in nineteenth-century cartography, in Gillman's brief description, and in the kind of footnote that records loss rather than survival.