They are fulachta fia, a type of prehistoric cooking site found in great numbers across Ireland, and their clustering here is quietly suggestive of repeated, deliberate use of a particular stretch of land.

A fulacht fia typically consists of a horseshoe-shaped mound of fire-cracked stone beside a trough, into which water was poured and heated stones were dropped to bring it to the boil. The method is ancient and practical, and the sites tend to cluster near water, which makes the Brownstown valley a plausible location: the ground is flat and persistently wet, fed by numerous streams and springs. All three mounds were identified during fieldwork in 1987, and their linear arrangement across the valley floor suggests they may have been used in sequence or in relation to one another, though whether that reflects different periods of activity or some more organised use of the space is difficult to say. The site described here is the most easterly of the three.