But the charcoal smears and fire-cracked stones packed into this particular hollow near Station Road in Portmarnock point to something far older than the suburban housing that now surrounds it. What was uncovered here is a burnt mound trough, one of the more quietly enigmatic features of the Irish Bronze Age landscape, and it dates to somewhere between 2135 and 1920 BC.

Burnt mounds are among the most frequently found prehistoric monuments in Ireland, yet they remain somewhat mysterious. The basic principle involves heating stones in or near a fire and then dropping them into a water-filled trough to bring the water to a boil, a method used when pottery large enough for cooking or other heat-intensive tasks was unavailable or impractical. Over time, the spent, shattered stones accumulate into a characteristic crescent-shaped mound beside the pit. The Portmarnock example was identified initially through geophysical survey, which detected anomalies beneath the surface, and then confirmed by test excavation carried out in 2004 under licence by Margaret Gowen and Co. Ltd on behalf of Ballymore Residential Ltd. The full excavation that followed, directed by Gill McLoughlin of Courtney Deery Heritage Consultancy Ltd and reported in 2020 on behalf of Sherman Oaks Ltd, revealed an isolated oval pit measuring 2.8 metres by 1.28 metres and roughly half a metre deep. Within two metres of the trough, three possible postholes were recorded to the north, northeast, and southeast. McLoughlin suggested these may have formed part of a windbreak, a simple structure that would have made sustained outdoor heating more manageable in exposed conditions.

The site itself is not publicly accessible as a monument in its own right; it was excavated as part of a development process and now lies within a residential area off Station Road, Portmarnock. For those interested in following up on the archaeology, McLoughlin's final excavation report was submitted to the National Monuments Service and details of the site have been compiled by Caimin O'Brien. The real interest here is less about visiting a visible feature and more about what the find represents: a moment of ordinary Bronze Age activity, preserved in cracked stone and charcoal, located not in some remote upland but on the coastal edge of what is now one of Dublin's busier commuter settlements.