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An Avalanche on Mars

What caused this sudden cloud of dust on Mars? An avalanche!
The first avalanche imaged in progress on another planet was
recorded last month on Mars by NASA'srobotic Mars Reconnaissance
Orbiter. Visible in the above picture, digitally rescaled, are
several layers of white ice thawing over red rock, with darker
colors toward the right indicated Martian soil that mixed with
lesser amounts of ice. As the cliff of over 700 meters high was
thawing, falling ice crashed down raising plumes of ice and dust
so thick they cast visible shadows. The scarp has slopes with
grades greater than 60 degrees. The entire scene is illuminated
from the upper right by the Sun. A thaw occurs each spring in the
Northern Hemisphere of Mars, as the warming climate causes solid
carbon dioxide ice to sublimate directly to vapor. Studying such
avalanches allows planetary geologists to better understand soil
configurations on Mars.