In the pastureland of Killeroran, County Galway, there is a shallow hollow in the ground, the kind of feature that the eye might pass over without a second thought. On older Ordnance Survey maps, however, it was marked with hachures, the small radiating lines cartographers used to indicate a depression or earthwork, lending it a faint air of significance it may or may not deserve.

When the site was inspected in 1984, the feature turned out to be a disused gravel pit, most likely dug sometime in the nineteenth or early twentieth century. Gravel extraction of this kind was common across rural Ireland during that period, when road improvement and drainage work created a steady local demand for material that could be dug from the ground without much ceremony and used nearby. The 1926 revision of the six-inch Ordnance Survey map had recorded the hollow faithfully, as it recorded countless such features across the country, without distinguishing between the archaeologically significant and the merely practical. That cartographic neutrality is part of what makes old maps so useful, and occasionally so misleading.