It only came to light because of an engineering decision made in the 1960s: when the Inny River was drained, water levels across Lough Derravaragh dropped, and an ancient foreshore was exposed to the air for the first time in millennia. What appeared was not dramatic stonework or visible structure, but something quieter and, in its way, more telling: a scatter of worked chert fragments and implements left behind by people who had camped or settled here thousands of years earlier.

The site was examined and described by Professor Frank Mitchell, whose 1972 publication recorded it as Site 2a. Mitchell noted that the foreshore at Clonava exposed outcrops of shaly and flaggy limestone interspersed with layers and nodules of chert, and that among these outcrops lay chert debitage, the waste flakes and fragments produced when stone is knapped into tools, alongside two carefully worked pointed picks. Clonava Island itself is a knoll of calcite mudstone threaded with bands of chert, and the material here has a rather unusual banded structure, sometimes called "festoon" chert, that tends to disintegrate when exposed to weather over time. This fragility makes the survival of any worked pieces all the more notable. The source of the raw material may have been Knockeyon Hill nearby, where natural outcrops of the same distinctive chert occur and where quarrying activity has been identified.

Nothing of the lithic scatter remains visible on the surface today. The exposure that made discovery possible also accelerated the weathering of the chert, and the foreshore that briefly revealed its Mesolithic past has since given up most of what it had to show. What the site leaves behind is less a place to visit than a question: how many other ancient shorelines across Ireland's midland lakes are waiting beneath the waterline, preserved precisely because they have never been exposed.