No Martians Were Hurt In The Making Of This Picture
But wow! What a picture.
Sometimes you just have to be amazed by the wonder of it all. The high-resolution cameras of the Mars Reconnaissance Orbiter, caught this avalanche as it caused a dust cloud to be raised on Mars. From the HiRISE blog page:
The scarp in this image is on the edge of the dome of layered deposits centered on Mars’ north pole. From top to bottom this impressive cliff is over 700 m (2300 ft) tall and reaches slopes over 60 degrees. The top part of the scarp, to the left of the images, is still covered with bright (white) carbon dioxide frost which is disappearing from the polar regions as spring progresses. The upper mid-toned (pinkish-brownish) section is composed of layers (difficult to see here) that are mostly ice with varying amounts of dust. The darkest deposits below form more gentle slopes, less than 20 degrees, and are mainly composed of two materials: mid-toned layers, possibly ice-rich, that form small shelves, and more mobile, widespread, sand-sized dark material. The wavy forms on the flatter areas to the right are dunes. The upper, steepest section, which appears highly fractured due to blocks pulling away from the wall, is the likely source zone for the falls. The precise trigger mechanism is not yet known, although the disappearance of the carbon dioxide frost, the expansion and contraction of the ice in response to temperature differences, a nearby Mars-quake or meteorite impact, and vibrations caused by the first fall in the area, are all possible contributors.
Big Hat Tip to Phil Plait at Bad Astonomy.