Racetrack Playa is about 4 kilometers long (2.5 miles – north to south) and about 2 kilometers wide (1.25 miles – east to west). The surface is covered with mudcracks and the sediment is made up mainly of silt and clay.
The moving rocks, some of which are said to weigh close to hundred pounds, normally leave a long trail behind them.
But the question has always been: what makes them move in different directions and when do they move?
Thus, the ‘traveling’ of the rocks has always been a phenomenon and a mystery since nobody has seen any one rock in motion.
But curious mind of scientists have always ways of finding out and this link I am sharing here will tell you how they unraveled the longstanding mystery: http://blogs.discovermagazine.com/d-brief/2014/08/27/secret-behind-death-valleys-sailing-stones-revealed/#.VABrp6Pcy0s.
An interesting discovery, indeed.