It is called a ringfort on the official record, but the archaeologist who dug into it concluded, with some precision, that it was never actually a fort at all. The curving bank and fosse, running in an arc from northwest to southeast across the slope, was almost certainly built to move water rather than repel people.

The site sits within a dense archaeological complex on what was historically identified as Temair Erann, the supposed ancient burial ground of the Ernai tribe. The antiquary T. J. Westropp wrote about the area in the early twentieth century, and between 1934 and 1935 Seán P. Ó Ríordáin excavated a group of monuments here, labelling them in a Northern Group of forts numbered sequentially across the hillside. The earthwork in question was his No. 9, positioned between ringforts No. 8 and No. 10, and a fosse is simply a ditch, usually dug as part of a defensive enclosure around a ringfort. When Ó Ríordáin cut a section across No. 9, he found a few post-holes but no evidence of a complete enclosing ditch or palisade. His conclusion was that the arc was constructed to connect the two neighbouring forts and, more practically, to intercept and redirect the downhill wash of water from the wetter ground above. The evidence he offered was elegant in its simplicity: the land below the earthwork is dry, with bracken; above it, rushes grow in damp ground. The eastern sides of both adjacent ringforts had also been given more complex defences than elsewhere on their circuits, suggesting that all three elements were strengthened together in a single episode of landscape management rather than military planning.

The earthwork lies in the northern quadrant of the broader Cush complex, within a large field system that is itself a scheduled monument. The curving arc is visible on aerial and satellite imagery, running clearly across the pasture. On the ground in rough grazing land, the feature is easier to read when vegetation is low, and the contrast between the dry bracken below and the rush-choked ground above remains, apparently, much as Ó Ríordáin observed it ninety years ago.