NASA Mars Picture of the Day: Inverted Valley in Arabia

Mars Global Surveyor Mars Orbiter Camera

MGS MOC Release No. MOC2-920, 24 November 2004

NASA/JPL/Malin Space Science Systems

Ancient valleys that may once have been the conduits through
which water flowed are common on the surface of Mars. They
are also found–filled and buried–in the subsurface, preserved
in the rock record. In addition, erosion
may take what was once the floor of a valley and leave it
as a high-standing, flat-topped ridge.
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC)
image shows a valley in eastern Arabia Terra that, in just one
picture, exhibits both negative and positive relief forms.
In negative relief, the valley is just that–a valley. In
positive relief, instead of a valley, the former
floor is now the top of a broad ridge. This
MOC image is particularly instructive, because the transition
from negative to positive (then back to negative and then
again to positive) relief is captured in one small area.
These landforms are located
near 32.5°N, 314.1°W.
The image covers an area about 3 km (1.9 mi) wide.
Sunlight illuminates the scene from the lower left.

Malin Space Science Systems and the California Institute of Technology
built the MOC using spare hardware from the Mars Observer mission.
MSSS operates the camera from its facilities in San Diego, California.
The Jet Propulsion Laboratory’s Mars Surveyor Operations Project
operates the Mars Global Surveyor spacecraft with its industrial
partner, Lockheed Martin Astronautics, from facilities in Pasadena,
California and Denver, Colorado.