NASA's Mars Global Surveyor shows an inverted valley in eastern Arabia Terra on Mars. The relatively flat-topped ridge was once the floor, or a material covering the floor, of an ancient martian valley.

10 September 2005
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows an inverted valley in eastern Arabia Terra. The relatively flat-topped ridge that runs down much of the length of this picture was once the floor, or a material covering the floor, of an ancient martian valley. The floor material was harder and more resistant to erosion than the rocks into which the valley had been cut. Thus, erosion removed the rocks that were cut by the valley, and then removed additional rocks that were lower than the valley floor, leaving what was once a valley as a high-standing ridge.

Location near: 11.4°N, 312.9°W
Image width: width: ~3 km (~1.9 mi)
Illumination from: lower left
Season: Northern Autumn

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