This is a cashel, the stone-built variant of the more familiar earthen ringfort, and the wall enclosing this one is still substantial enough to measure: roughly two metres wide and standing about a metre high, encircling a roughly circular interior some fifty metres across. That a structure of this scale can disappear so completely into the landscape is a quiet reminder of how thoroughly the countryside absorbs its own archaeology.

Cashels and ringforts were the dominant form of rural settlement in early medieval Ireland, used broadly from around the fifth to the twelfth centuries. They typically enclosed a farmstead and its associated buildings, offering a degree of protection for people and livestock rather than serving any serious military purpose. The stone construction of a cashel, as opposed to the earthen banks of a rath, tends to suggest either a region where stone was readily available or an owner with the resources to use it, and the landscape around Lough Mask and Lough Carra in south Mayo is well supplied with both field stone and a long tradition of its use. The site at Creggarve was recorded as part of a local archaeological survey of the Ballinrobe district, published in 1994, which documented a wide scatter of monuments around the shores of those two lakes.