The enclosure at An Carn Mór Thiar measures approximately 50 metres north to south and 43.5 metres east to west, and its boundaries are defined by two banks with a fosse between them. A fosse is a ditch, typically dug to complement a raised bank as part of an enclosing boundary, and here the fosse runs from the south-west around through the north to the north-east, though it has largely been filled over time with field-clearance rubble, the accumulated result of generations of farmers removing loose stone from the surrounding land. Along the eastern side, rather than a second built bank, a natural or cut scarp serves as the inner enclosing element. The outer bank survives only along the northern stretch. The burial ground occupying the north-eastern interior quadrant is recorded separately, and its presence within an older enclosure is not unusual in an Irish context; early ecclesiastical or community burial sites were sometimes established within pre-existing earthworks, reusing a bounded space that already carried a degree of separation from the ordinary landscape. The site was noted by McCaffrey in 1952 and surveyed again by de hÓra in 1991, lending it a modest documentary trail across the second half of the twentieth century.