At Claremadden in County Galway, a hachured marking on the 1945 revision of the OS 6-inch map, the kind of cartographic shorthand used to indicate a depression or earthwork, drew enough attention to prompt a site visit in 1984. What the surveyor found was a subcircular hollow, heavily overgrown, almost certainly the remains of a disused sand or gravel pit.

The pit is thought to date to after 1700, which places it firmly in the era of improved road-building, estate landscaping, and agricultural drainage that transformed the Irish countryside during the eighteenth and nineteenth centuries. Sand and gravel extraction of this kind was commonplace, used for everything from road surfacing to mortar-making, and the resulting pits were simply abandoned once a source was exhausted, left to flood, collapse inward, or disappear under vegetation. Because the feature post-dates AD 1700, it falls outside the scope of prehistoric and early historic archaeology, which is why it was noted and then, in a sense, set aside. Its presence in any record at all is largely a consequence of cartographic ambiguity, of a mark on a map that once suggested something more ancient than it turned out to be.