Long description
This figure is a greyscale satellite image of the martian surface. A delta area is evident, from left to right across the image, fanning out towards the right. Two lines are overlain. A green line meanders from left (from a region labelled Nereta Valles) to right to the centre of the image, and then winds around the central area, to the south of a region labelled Belva. A purple line meanders in a roughly circular pattern to the right of the green line, in the right hand side of the image.