Imagine the sight of Death Valley National Park is something akin to scientific pornography for hard-rock geologists. There are the obvious soaring mountains and abysmal valleys, of course. But in most other places on Earth, the folding and buckling of rocks, the colliding of crustal plates, the shores of advancing and retreating lakes, the evidence of volcanic activity, the scrape of glaciers across rock, the subtle and not so subtle effects of erosion are covered over in grass or dirt, in snow or ice. The Earth is a modest mother, but Death Valley is, for the most part, naked. It is also the only place on Earth where geology itself has made me laugh out loud. I am thinking specially of an area in the northwest section of Death Valley called the Racetrack, where, inexplicably, rocks as big as microwave ovens go zipping across the desiccated mud for distances of more than half a mile (880 m). The evidence is all there: deep tracks in the surface, with a rock at the end. One concludes, reluctantly, that the rocks somehow traveled a couple of hundred yards, leaving a telltale trail behind. There are over 150 of these roving rocks. But no one has ever seen them move.
The Racetrack proper, about three miles long (4.5 kilometers) and a mile wide (2 kilometers), is what is called a playa, a dry, smooth lake bed. The Racetrack is a mere two inches higher on the north end than the south. Flat as a pool table. The surface is sun-baked mud, hard as rock, and patterned in polygons the size of doughnuts. It is an otherworldly sight, and there is a sense on the playa of post-apocalyptic silence, broken only by the whisper and wail of the wind. This impression is compounded by the Grandstand, a 73-foot-high (22 meters) island of rounded bedrock at the north end that looks like the summit of a mountain buried in a sea of sediment. One supposes that observers—rock-racing fans—might sit on the Grandstand, as at a horse race, and observe stones zooming toward them from the southern end of the playa.
I had plenty of time to contemplate the Grandstand. I'd driven 30 miles (48 kilometers) from Ubehebe Crater, and the gravel road proved to be less brutal than expected, so I arrived at the Racetrack in the early afternoon. The best time to see the rock raceways is around dawn or dusk, when the slanting rays of the sun show the tracks to their best advantage.