NASA's Mars Global Surveyor shows a gullied crater wall on Mars. The gullies have formed in a thick, smooth-surfaced mantle that covers the crater wall.

14 June 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a gullied crater wall at 1.5 meters (5 feet) per pixel resolution. The gullies in this case have formed in a thick, smooth-surfaced mantle that covers the crater wall. Formation of these gullies might have involved a fluid such as water, or perhaps could have formed by avalanching of dry debris. The Mars science community is still discussing, debating, and making new observations of martian gullies to better understand their origin and implications. These gullies are located near 33.8°S, 201.6°W. The image covers an area about 3 km (1.9 mi) across. Sunlight illuminates the scene from the upper left.

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