NASA's Mars Global Surveyor shows gullies formed in the terraced wall of an impact crater on the floor of a larger crater on Mars.

8 June 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) picture shows gullies formed in the terraced wall of an impact crater on the floor of a larger crater near 39.1°S, 200.7°W. Gullies such as these are fairly common in craters and depressions at southern middle latitudes. They also occur in some areas at northern middle latitudes and in both polar regions. They may have formed by liquid water, or not--the Mars science community is still debating and discussing the issue. This picture covers an area about 3 km (1.9 mi) across. The scene is illuminated by sunlight from the upper left.

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