Bonneville Salt Flats

Where it sits. The Bonneville Salt Flats lie in Tooele County in far north-western Utah, pressed against the Nevada line, a hard white pan roughly nineteen kilometres long and eight wide at an elevation of about 1,280 metres. Interstate 80 runs along their southern edge, and the mountains of the Silver Island Range stand out to the north like islands, which is exactly what they once were: the flats are the floor of Lake Bonneville, the Pleistocene inland sea that covered much of what is now Utah until it drained catastrophically around 15,000 years ago. What remains is an estimated 147 million tons of salt, about ninety per cent of it ordinary sodium chloride, laid down in a crust nearly a metre and a half thick at the centre and thinning to a few centimetres at the margins. The land is public, managed by the Bureau of Land Management, and open to visitors.

The story behind it. The geologist Grove Karl Gilbert named the basin for Benjamin Bonneville, a US Army officer who explored the Intermountain West in the 1830s. The flats entered motoring history in 1907, when Bill Rishel and two Salt Lake businessmen drove a Pierce-Arrow onto the salt to see whether it would carry a car; it did. A railway crossed the pan in 1910, the first permanent route over it, and in 1914 Teddy Tetzlaff set the first land speed record here. From then on the salt belonged to speed. The Bonneville Speedway, marked out on the crust each summer, has hosted the fastest wheel-driven machines ever built, and events such as Speed Week in August still draw hundreds of home-built streamliners, lakesters and motorcycles to run the black-lined course. The Pontiac Bonneville and the Triumph Bonneville both took their names from this ground.

On screen. A dead-flat white plane under a huge sky is one of the most useful images in cinema, and directors have used it for four decades. Independence Day (1996) and its sequel shot here; so did Warlock, SLC Punk, The Brown Bunny, Gus Van Sant's Gerry, Terrence Malick's The Tree of Life, the Matthew Barney Cremaster cycle, Knight Rider, Top Gear and The World's Fastest Indian, the Anthony Hopkins film about Burt Munro's record runs, which was shot on the salt that made him. The most inventive use is Pirates of the Caribbean: At World's End, which turned the flats into Davy Jones's Locker — the white afterlife desert where the Black Pearl sits stranded and the crabs come. In every case the appeal is the same: no vegetation, no structures, no scale cues, and a horizon that reads as either an alien planet or the end of the world depending on the lens.

What you actually see today. Take exit 4 from Interstate 80 and a paved access road runs about eight kilometres north to a small parking area at the edge of the salt. There is a vault toilet and nothing else — no water, no shade, no fuel. When the pan is dry and firm you may drive onto designated areas, and this is one of the few places on earth where an ordinary rental car can be pointed at a horizon and left in a straight line. Do not do it when the surface is wet or soft; vehicles sink through the crust every year, recovery is expensive, and the damage to the salt is real. Salt is also viciously corrosive: rinse the underbody at the first opportunity. Eastbound on I-80 a rest area holds Karl Momen's Metaphor: The Tree of Utah, a 26-metre concrete-and-tile sculpture completed in 1986 that has become the unofficial gateway marker to the flats.

The salt is changing. The crust is thinner than it was. BLM studies have documented reduction in thickness, particularly in the north-western area where racing takes place, and the pan's overall extent has contracted over recent decades. Decades of potash extraction from adjacent brines are widely implicated, and a salt laydown programme now returns brine to the flats each winter in an attempt to rebuild the surface. Racers have lost seasons to soft or flooded salt. It is worth understanding that this landscape, for all its apparent permanence, is an actively managed and diminishing resource.

Getting there and timing. Wendover sits about thirteen kilometres west on the state line and supplies fuel, food and rooms; Salt Lake City is around 190 kilometres east on the interstate. August delivers the hardest crust and the racing calendar. Late autumn through spring often leaves a two-centimetre film of standing water on the pan, which is when it turns into the mirror that photographers travel for — the sky doubled underfoot at sunrise, walkers apparently suspended in nothing. Summer temperatures are punishing and the glare off white salt is severe enough to burn the underside of a chin; sunglasses, sunscreen and several litres of water are not optional.