There are three notable features in this image of the Sirenum Fossae region of Mars. The image shows the region centred at about 28°S, 185°E. The largest impact crater in box 1 is around 50 kilometres in diameter, and indicates that this region is ancient because such large craters rarely formed in more recent times. There is a large valley system in box two, and two parallel lines to the left-hand side of the box. These form a graben.
The central impact crater in box three has a diameter of about 28 km, and is relatively young because its centre remains jagged rather than having been smoothed by erosion. The youngest crater is the small 9 kilometre-diameter crater. The crater at the bottom of the box is 34-km across, and the largest crater in the box, 56 kilometres in diameter, is the oldest and most eroded.
Credit: ESA/DLR/FU Berlin (G. Neukum).