North is up, latitude and longitude of the corners are labeled. Local context for three MOC images described below. Each of these MOC images was reprojected and resized to fit within this base map. The base map is a mercator-projected mosaic of Viking Orbiter images 631a41, 631a43, 631a44, 631a45, 631a46, and 631a48. The Viking images were taken on the 631st orbit of Viking 1 in 1978.
Illumination is from the upper right, north is up.
Local context for MOC image 21905. Illumination is from the upper right, north is up. 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.