15 December 2005
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a somewhat sinuous, nearly flat-topped ridge, located in eastern Arabia Terra. The ridgetop was once the floor of a valley, perhaps carved by running water. The valley floor, or material that covered the floor, was more resistant to erosion than the surrounding rock into which the valley was cut. Thus, over time, the valley disappeared and its floor was left standing high as a ridge. Inverted valleys are common on Mars; they also occur on Earth.
Location near: 10.8°N, 313.2°W
Image width: width: ~3 km (~1.9 mi)
Illumination from: lower left
Season: Northern Winter