Gullied Crater Wall
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows gullies in the southeast-facing wall of an impact crater in northwestern Acidalia Planitia. Gullies are common in southern middle-latitude craters, and much less common in cases like the one shown here, found at a northern middle latitude. Debate continues within the Mars science community as to the origin of the gullies, whether by groundwater, melting ice or snow, or an alternative fluid such as carbon dioxide.
Location near: 41.4Â°N, 44.8Â°W
Image width: ~3 km (~1.9 mi)
Illumination from: lower left
Season: Northern Autumn