On the north side of Death Valley National Park in Inyo County, California, is a scenic dry lake called Racetrack Playa. The lake, which has no vegetation and rarely sees a drop of rain, gets its name from a strange geological phenomenon that occurs in it.
Racetrack Playa is home to hundreds of sailing stones. These stones—most made of dolomite and ranging in size from just a few ounces to several hundred pounds, mysteriously move by themselves with no human or animal intervention. The stones leave tracks that are often hundreds of feet long, and they can change direction several times on their journey. The only way scientists know the rocks have moved is by these tracks; no human has actually ever seen the rocks move with their own eyes.
So, how do the rocks move? Since scientists have never actually seen them in motion, they only have theories. One theory is that, on the rare occasions that the area gets rain, the lakebed becomes slick, allowing the rocks to be pushed by the winds, which can reach upward of 90 miles per hour. Another explanation is that the occasional rainfall actually freezes (nights can get frigid in the desert) and the rocks slide on the thin sheets of ice.
Although no video recordings of the rocks have ever been made—the slight movements happen in a few seconds over the course of many years, making it impossible to tape—geologists have named and mapped each of the stones (for some inexplicable reason the stones all have female names). The most interesting stone is named Karen, a 29 × 10 × 29 inch block of dolomite weighing 700 pounds. The scientists knew Karen had moved quite a bit in the past—her track was 570 feet long—but from the time they started mapping the stones, Karen hadn’t budged an inch. Then, some time during the unusually wet winter of 1992-1993, Karen vanished. The geologists were utterly perplexed and despondent over having lost one of the biggest of the sailing stones.
Karen was finally found in 1996 by geologist Paula Messina, more than half a mile away from her original trail. To this day, no one knows how she got there.