Where the stream has cut into its own bank, a dark layer of burnt material is exposed in cross-section, a telltale signature of a fulacht fia, one of the most common yet persistently mysterious monument types in the Irish archaeological record.

A fulacht fia, sometimes called a burnt mound, is the remains of an ancient cooking or processing site, typically consisting of a mound of fire-cracked stones and charcoal accumulated beside a water source. The method involved heating stones in a fire and dropping them into a water-filled trough to bring the water to a boil, a practice that left behind a characteristic horseshoe-shaped mound of shattered, heat-reddened stone. Thousands of these sites survive across Ireland, with a particular concentration in the south and west, most dating to the Bronze Age, roughly between 1800 and 800 BC. Their proximity to running water was not incidental; a reliable stream was essential to the process. At Lyradane, the stream that once supplied the site is still there, and it is the erosion of its bank that has made the burnt layer visible, offering a small, unintentional window into what lies beneath the turf.