The quarry at Carrowmore in County Clare managed exactly that. Recorded as an earthwork in 1992 and again in 1996, it had already been marked on the 1920 six-inch OS map using hachures, the fine parallel lines cartographers used to indicate a depression or raised feature in the ground, and on the later twenty-five-inch map it was described plainly as a pit. By the time anyone went to look at it properly, in 1999, the area had been levelled. Whatever hollow or cutting had once been significant enough to chart was gone.