mdekato writes "MSNBC reports that NASA's Mars Reconnaissance Orbiter has captured an avalanche on Mars' surface as it happened. Very good still images show what must have been an awesome sight. 'The full image reveals features as small as a desk in a strip of terrain 3.7 miles (6 kilometers) wide and more than 10 times that long, at 84 degrees north latitude. Reddish layers known to be rich in water ice make up the face of a steep slope more than 2,300 feet (700 meters) tall, running the length of the image. Mars' north pole is covered by a cap of ice, and it even snows there. The scientists suspect that more ice than dust probably makes up the material that fell from the upper portion of the scarp.'"