In this case, the relationships strongly suggest lava, which today is hardened to rock throughout. Such ridges can be caused by collision of the hard, crusted plates as they move over a fluid interior. Illumination is from the right. This picture was taken on the 219th orbit of Mars Global Surveyor on April 4, 1998. Illumination is from the right.
North is approximately up, illumination is from the 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.