The carved surface of a prehistoric roofing slab is not supposed to face downward, hidden from the light it was presumably meant to communicate with. Yet that is precisely the situation at Hempstown Commons, where a decorated stone spent an unknown number of millennia with its decorated face pressed against the dead inside of a burial chamber, invisible to anyone above ground.

In 1949, a gravel-extraction operation involving bulldozers on the highest point of a low drumlin, one of those smooth oval hills shaped by glacial drift, accidentally broke open a cist, a small stone-lined burial box of the kind typically associated with the early Bronze Age. The grave was roofed by two slabs. One of them, a roughly triangular sandstone piece approximately a metre long and up to 0.7 metres at its widest, turned out to carry decoration on its underside, the surface that had been facing inward. The carving, known as rock art and produced by a technique called pecking, in which a harder stone tool is repeatedly struck against the surface to chip away the material, included several distinct motifs: a penannular or horseshoe-shaped pecked area, small cupmarks, a pair of conjoined circles, irregular patches of pecking, and a lozenge-shaped area with both a pecked fill and an incised outline along its edges. The combination is unusual. Cupmarks and penannular forms appear widely in Irish and British prehistoric rock art, but the lozenge with its incised outline gives this particular slab a slightly more complex character. The discovery was published by Hartnett in 1950 and subsequently noted by Waddell in 1970, and the site carries a formal monument record under the reference KD020-015001.

The circumstances of the find raise questions that the archaeology cannot fully answer. Whether the decorated face was deliberately turned inward when the cist was constructed, or whether the slab was reused from some earlier context without particular regard for which side faced where, remains unclear. Either possibility has its own implications for how the carving was understood by the people who placed it there.