On the 1931 edition of the Ordnance Survey six-inch map, the feature was marked with hachures, the short radiating lines cartographers used to suggest raised or broken ground. It was only when someone looked at it in person, in 1984, that the hachured marking resolved itself into something more mundane and more specific: a pit in the ground, a quarry cut into the landscape and then, at some point, simply left.