Because of this obscuration, many of the small features that could be used to determine the origin of these valleys are missing. Crater-like rings within the valley adjacent to the wall are the resistant portions of impact craters that survived the retreat of the wall as the valley widened. This is evidence that processes of valley widening were relatively gentle, probably related to groundwater seeping from beneath a resistant cap of volcanic rock. MOC image 24106 was taken on April 14, 1998.
North is approximately up, illumination is from the lower right.
This MOC image is made available in order to share with the public the excitement of new discoveries being made via the Mars Global Surveyor spacecraft. Release of this image does not constitute a release of scientific data. The image and its caption should not be referenced in the scientific literature. Full data releases to the scientific community are scheduled by the Mars Global Surveyor Project and NASA Planetary Data System. Typically, data will be released after a 6 month calibration and validation period.