Plate-Rafted Morphologies MOC image 21905, showing the textured surface in Elysium Basin. 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.