The Hole sits in the Tabular Hills of the North York Moors, upstream of the small villages of Levisham and Lockton. From the lay-by on the A169 - the road that climbs over the moors between Pickering and Whitby - the view opens suddenly, with no warning and no parking discipline whatsoever. The land falls away into a near-perfect amphitheatre, the slopes tufted with bracken and heather, the floor green with grazed pasture. Levisham Beck threads along the bottom. To the north and east the moor stretches flat, dark, and treeless, but here the earth dips into a soft, bowl-shaped wound. The scale takes a moment to register: those tiny dots in the bottom are sheep.

The Hole was carved by spring-sapping. Water welling up from the hillside undermines the slopes above, dislodging grain after grain until the slope above collapses, and the process resets a little further back. Over thousands of years, a narrow valley widens and deepens into the cauldron you see today. The process has not stopped. The springs still seep, the slopes still creep, and the Hole is still slowly enlarging itself - though too slowly for any human visitor to notice. It is a landscape being made in real time, on a timescale where human lifetimes are below the threshold of measurement.

Wade is a folkloric giant of the North York Moors, credited with everything from the Roman road on Wheeldale to half the unusual landforms in the region. The Hole of Horcum is his temper tantrum frozen in geology. The name itself is older and less mythic: early forms include Hotcumbe, Holcumbe, Horcombe, and Horkome. The first element is Old English horh, which translates, unromantically, as 'filth' - probably a reference to muddy or marshy ground at the valley floor. The second, cumb, is Brittonic Celtic for a bowl-shaped valley, a word that survives in West Country combe and the Welsh cwm. Saxon farmers and Celtic place-namers and Yorkshire storytellers have all left their marks on the rim of this single hole.

A footpath circles the entire Hole, about six and a half miles around if you keep to the top. The walk gives you a continually shifting view of the bowl below: in summer, gorse and bell heather brighten the slopes; in late August and September the moor goes purple as the ling heather flowers; in winter the wind off the moor cuts down to the bone and the bracken rusts to red-brown. Down at the bottom, sheep graze where springs still feed the beck. The Hole is among the most photographed landscapes in the national park, but the photographs cannot quite hold its scale - a measure, perhaps, of the difference between a giant's tantrum and the slow patience of water.