Grooved terrain, the term applied to the fractured surface in the bottom left quadrant of this picture, occurs in a discontinuous ring around Olympus Mons. The origin of this terrain is unknown, but it has been suggested that it occurs at the surface of vast thrust sheets caused by the loading of the crust by Olympus Mons. Another suggestion is that the terrain is formed by erosion of ash flow tufts that originated from Olympus Mons. To the northeast, young lava flows transect the grooved terrain and an older fractured surface. The image is about 300 km across.
North is to the top of the image.