In the pastureland outside Caltra in County Galway, a small circular hollow sits largely swallowed by vegetation, its edges softened by decades of grass and growth. It is the kind of thing most walkers would step around without a second thought.

On the 1932 edition of the OS six-inch map, the spot is recorded using hachures, the short radiating lines cartographers use to suggest a depression or raised feature in the terrain. When someone went to look at it properly in 1983, the hollow turned out to be roughly circular and heavily overgrown, most likely the remains of a disused sand or gravel pit. Such pits were once common features of the rural Irish landscape, dug to extract material for road repairs, building work, or the maintenance of farm lanes, then quietly abandoned when the resource ran out or the need passed.