The discovery came during the Lough Mask Regional Water Supply Scheme in 2001 and 2002, when the material appeared in cross-section inside the pipe trench at roughly half a metre below the road surface. It was immediately apparent that the deposit continued under the road to the north and out into the adjacent field to the south, and the route of the pipe was subsequently altered to avoid disturbing it further.

A charcoal sample taken from the site produced a radiocarbon date of 3687 plus or minus 43 BP, placing its use somewhere between 2201 and 1957 BC, firmly within the Early Bronze Age. The site is what archaeologists call a burnt mound, the remains of what was probably a repeatedly used outdoor cooking or heating site, where stones were fired and then plunged into water-filled pits to bring them to the boil. The scorched and shattered stones were then raked aside into the characteristic low mounds that survive in the landscape. What makes the Treannaskehy find particularly interesting is its company: a second burnt mound sits roughly 60 metres to the south-west, and there was a fulacht fia, a closely related type of site also associated with fire, water, and heated stones, approximately 35 metres to the north-east. The clustering of these monuments across a small area of what was once probably wetter, more boggy ground suggests this corner of Mayo saw repeated use over generations, though the road surface now seals much of what remains.