Makhtesh Ramon is a hollow in the Negev desert of southern Israel, forty kilometres long and five hundred metres deep. Nothing struck it and nothing erupted. Water made it. Rock arched up here, the top wore through, and the soft interior drained away through a single gap in the rim. The result is a landform found nowhere on Earth but this desert and the Sinai. The road hairpins off the rim and takes you down onto the floor, past coloured sands and low black volcanic hills. Anywhere you stop down there, the walls stand around you in bands, two hundred million years of old seabed read from the bottom up. At HaMinsara a short trail climbs a hillside of quartzite prisms in heaps, squared and sawn-looking, as though a workshop had tipped over. Magma baked the sandstone here, the cooling split it into columns, and the edges are still sharp. On the northeastern slope another outcrop is studded with coiled ammonite shells, some coin-sized, some as wide as a tractor wheel. Most were chipped off by visitors over the years; what is left stays where it lies.
The animals divide between rim and floor. Nubian ibex walk up onto the clifftop promenade at Mitzpe Ramon in the early morning and crop the grass with the crater dropping away behind them; they never left. The wild asses below did. The Syrian wild ass was hunted out last century, so a close relative, the Persian onager, was released here and now runs the floor. At night nothing is lit down there at all. On a moonless one the far wall disappears, and the stars come out thick over the gap where it was. On cold winter mornings, not every one, air chilled overnight on the plateau slides over the edge at dawn and pours down the cliff as a slow white fall of fog that evaporates as it warms. It lasts minutes. Down on the floor, those bands in the walls all used to carry on over your head; what you are standing in is the part that is gone.