You might have noticed that for all researchers' fascination with the Martian landscape, it doesn't exactly do much in most photos. NASA's Mars Reconnaissance Orbiter has taken care of that. A single image taken in mid-February has captured no less than four avalanches in progress near the Red Planet's north pole. In the example shown here (in false color), a mass of fine dust and ice, possibly with bigger rocks mixed in, has broken off from a steep cliff over 2,300 feet (700 meters) high and sloping up to 60 degrees or more. The avalanche is traced by a cloud of fine material 590 feet (180 meters) across and extending 630 feet (190 meters) from the base of the cliff; a shadow beside the dust confirms that it extends into the volume above. NASA says the likely source of the spilled material is the uppermost, broken rock face (reddish) lying just below the mass of carbon dioxide frost (white) lining the scarp, which may have triggered the collapse as it melted. The agency notes that detailed measurements of the avalanches may reveal how quickly ice is eroding from the cliff and the exact proportion of ice and dust in the cloud.