(The Gist of Science Reporter) The Sailing Stones [MAY-2019]
The Sailing Stones
- Have you ever seen something moving by itself? Well, in Racetrack Playa
in Death Valley National Park of California large rocks slide on their own
without any human or animal intervention or any gravitational force. It is
the driest place in North America with temperatures hitting a record high of
56.7°C. Racetrack Playa is a barren lakebed, which offers the world's
strangest phenomenon of “sailing stones”.
- Well, normally rocks move during an avalanche but in Racetrack Playa
rocks move on a flat deserted landscape. The moving rock size is estimated
to weigh around 318 kg.
- These rocks are composed of dolomite and syenite, the same material as
of the surrounding mountains. They erode and tumble down to the parched
ground below. After reaching the surface of the playa, the rocks start
moving horizontally leaving long and smooth tracks behind. The location. The
rocks with rough bottomed surfaces tend to leave straight tracks while
smooth surface rocks tend to make 90 degree turn and wander. These rocks
have been observed since the 1900s for their mysterious movements.
- In 2014, for the first time scientists were able to record the movement
of the stones by time-lapse photography. According to their study published
in the journal PLoS ONE, the team of researchers installed several
time-lapse cameras around die playa and a weather station. They also
embedded GPS into some rocks of different sizes and waited for the rocks to
- The researchers called it the most boring experiment ever. But
eventually things got interesting one day when a significant amount of rain
and snow created a small pond in the desert. The pond cyclically froze at
night and thawed during the day. As the temperature gets warmer thin layers
of surface ice started breaking into large floating sheets of ice. Before
the icehad completely melted it got pushed by a steady light wind around
7-10 miles per hour. This pushed the floating ice sheets behind the rooks
and generated enough force to set the rocks in motion.
- Instead of floating and rotting, the rocks drive their way across the
wet muddy terrain, leaving behind their signature tracks. The results
strongly suggest that the sailing stones are the result of an ideal balance
of ice, water, and wind. The rocks won't move it there’s excessive amount of
water or ice, an excessive amount of sun, or not enough wind. Everything
must act in perfect harmony for the races to ensue.
Courtesy: Science Reporter