What makes it worth a second look is not its size but its inconsistency: the earthwork behaves differently depending on where you stand. To the north it is relatively broad and rises to a reasonable height on both its inner and outer faces; to the south it narrows considerably and shifts in character, becoming a slender stone bank constructed against a stepped natural scarp rather than a built-up earthen mound.

The site is classified as a cashel, a term used in Irish archaeology for a ringfort whose enclosure is defined primarily by a stone wall rather than an earthen bank, though here the distinction between the two is blurred. Ringforts in general were the dominant settlement form of early medieval Ireland, typically dating from roughly the fifth to the twelfth century, and most functioned as enclosed farmsteads for a single family and their livestock. This example at Carncash encloses a sub-circular area measuring approximately 25.5 metres north to south and 22.5 metres east to west, which is modest but within the normal range for such sites. There is no fosse, the external ditch that commonly accompanies earthen ringforts, and no clearly defined original entrance, though several breaks in the bank exist and may represent points of access at various periods of use or decay.