http://www.youtube.com/watch?v=u1hoiHvOeGc

Moving Rocks of Death Valley's Racetrack Playa

160 stones, the largest weighing 700 pounds !


http://geology.com/articles/racetrack-play...ding-rock-6.jpg


http://geology.com/articles/racetrack-play...ing-rocks.shtml

The truth: No one knows for sure exactly how these rocks move - although a few people have come up with some pretty good explanations. The reason why their movement remains a mystery: No one has ever seen them in motion!

Let's learn how they are thought to move.... ( go to link to read ideas about their movement )



The moving rocks, also known as sliding rocks or sailing stones, are a geological phenomenon found in Racetrack Playa, a seasonally dry lake (a playa) located in the Panamint Mountains in Death Valley National Park , California. The rocks move across the surface of the playa, leaving long tracks behind them as they go, without human or animal intervention. They have never been seen or filmed in motion.

Racetrack rocks only move once every two or three years and most tracks last for just three or four years. Rocks with rough bottoms leave straight striated tracks while those with smooth bottoms wander. Most of the moving stones originate from an 850 foot (260 m) high hillside made of dark dolomite on the south end of the playa, but some are intrusive igneous rock from adjacent slopes. Tracks are often tens to hundreds of feet (low to high tens of meters) long, a few to 12 inches (8 to 30 cm) wide, and typically less than an inch (2.5 cm) deep.


http://www.clipmarks.com/clipmark/8A9475AE...8-DF6328BB8E61/ ( photographs )