The escarpment that defines the Hampton Tableland is the Hampton Scarp, and it is, quite literally, a fossil sea cliff. The whole Nullarbor is an uplifted seabed, a sheet of fossil-rich limestone built from the skeletons of marine creatures and laid down when this region lay beneath a warm Cenozoic sea. As the land rose and the ocean withdrew across the Miocene, the surf line that had been gnawing at the coast was simply left behind, stranded inland. Today that abandoned shoreline forms the wall separating the elevated tableland above from the lower Roe Plains below. The sea is gone, but its old coastline still stands, sharp against the sky, marking a beach that no longer exists.

Geography here works like a staircase. The Hampton Tableland is the upper tread; below the scarp spreads the Roe Plains, a flatter belt blanketed in marine dunes that runs toward the modern coast and the cliffs above the Great Australian Bight. The Eyre Highway threads this lower step, hugging the foot of the escarpment so that travellers drive with the tableland's pale rampart rising on their left. Earlier trans-Nullarbor tracks took different lines across this country, but the great wall of limestone was always the landmark, the one fixed feature in a landscape that otherwise refuses to give the eye anything to hold.

Nullarbor comes from Latin words meaning "no trees," and the name has fooled people into picturing a dead, denuded waste. The reality is more generous. A surprising range of plants and animals has been recorded across the tableland, the country shifting from open limestone pavement to pockets of mallee and saltbush that shelter their own small communities of life. The deception runs deeper still: the apparently solid plateau is honeycombed underneath. Caves riddle the limestone, some of them holding remarkable features, the slow handiwork of rainwater dissolving rock over unimaginable spans of time. Above ground a blank tableland; below it, a hidden world of chambers and passages.