Measuring roughly twenty metres along its longer axis and sixteen metres across, the spread is distinguished by earth darkened with charcoal, the kind of discolouration that archaeologists recognise as a likely sign of ancient burning activity. It is, on the face of it, an unremarkable smudge in a working agricultural field, yet its very ordinariness is part of what makes it worth noticing.

Burnt spreads of this kind are among the more ambiguous features in the Irish archaeological record. The charcoal-enriched soil suggests sustained or repeated burning at some point in the past, though without excavation it is difficult to say whether the site represents a fulacht fiadh, the remains of a hearth or industrial process, or something else entirely. A fulacht fiadh, for context, is a type of prehistoric cooking or processing site typically identified by a mound of fire-cracked stone beside a trough, though the term is sometimes applied more loosely to any evidence of organised burning in the landscape. What survives at Aghavrin is the soil chemistry more than any visible structure, an oval shadow preserved beneath the plough line and recorded in the Archaeological Inventory of County Cork.