Sunday, May 30, 2010

Nanedi Valles

(Today's caption by ASU stinks once more, so here's my own:)

Above is a portion of Nanedi Valles, an 800-kilometer canyon that is located in Xanthe Terra and flows roughly to the northeast. Nanedi Valles is located to the west of the much bigger and more impressive Shalbatana Vallis. As can be seen in the image above, Nanedi Valles is characterized by being very sinuous; it also has only a few short branches, which are not seen in the photo. The canyon walls tend to be steep, while the floor is relatively flat. How Nanedi Valles formed is unclear. Competing theories include sapping (erosion caused by ground-water outflow), a flow of liquid beneath an ice cover or a collapse of the surface in association with liquid flow.

This photo was taken by THEMIS on board the 2001 Mars Odyssey spacecraft.

Photo credit: NASA/JPL/Arizona State University

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