Thomas Fagan, writing between 1845 and 1848, recorded accounts from local inhabitants who remembered an ‘extensive sepulture’ located just north of a nearby cromlech. According to these oral histories, the site had been dismantled during agricultural improvements sometime before Fagan’s visit, its stones presumably repurposed for field walls or other practical uses; a common fate for many ancient monuments during Ireland’s 19th century agricultural reforms.

The descriptions Fagan collected paint an intriguing picture of what might have been lost. Local people told him the burial ground contained numerous long graves, each one carefully constructed with large stone slabs forming the sides and ends, much like the chamber tombs found elsewhere in Ireland. What particularly caught the imagination were reports of the human remains discovered within: skulls and bones of ‘unusually large size’, though such claims about the stature of ancient peoples were common in Victorian antiquarian accounts and should be taken with a grain of salt. Perhaps more credible is the detail about some graves having floors bedded with sea sand and shells, which would align with known prehistoric burial practices in coastal areas.

While Fagan’s second-hand account tantalisingly suggests this could have been a destroyed megalithic tomb, possibly dating to the Neolithic period when such monuments were commonly built across Ireland, archaeologists remain cautious. Without physical evidence or more detailed documentation, the site remains classified simply as an unverified report. The Survey of the Megalithic Tombs of Ireland, compiled by Eamon Cody in 2002, includes this account but notes that more evidence would be needed to confirm whether Clonmass truly hosted one of Donegal’s lost prehistoric monuments.