In a field at Castle Ffrench in County Galway, two hachured markings, the small radiating lines cartographers use to suggest a depression or earthwork, appeared on the 1930 edition of the six-inch OS map roughly fifteen metres apart. They had the look of something worth recording. They were not, in any archaeological sense, remarkable at all.

When the site was inspected in 1984, what the map had preserved turned out to be the ghost of two infilled extraction pits, most likely dug for sand or gravel, probably sometime after 1700. The pits themselves had been filled in, but the ground remembered them. Darker patches of vegetation and a flush of nettles, plants that tend to colonise disturbed or nutrient-rich soil, marked the spots where the depressions had been. Because the features post-date AD 1700, they fall outside the scope of Irish prehistoric and early historic archaeology, which generally concerns itself with earlier remains. The map, in other words, had faithfully recorded something mundane, the kind of small-scale quarrying that would have been common across agricultural land, useful for building or drainage work, and entirely forgotten once the pits were no longer needed.