Ice and wind have left their mark on Colles Nili, a region characterised by numerous inselbergs or ‘escarpment outliers’ and marking the transition from the northern lowlands to the several thousand-metre-high Martian highlands in the south. The lowlands in the right (northern) half of the image are covered extensively by a thin layer of dark material. This is sand of volcanic origin that the wind has carried there. A large dune field has formed in the 15-kilometre-wide crater near the top of the image. The left, southern half of the image shows the transition to the Martian highlands. Between the 1000 to 2000 metre-high hills, debris-covered ice flows have shaped the landscape with streamlined moraines running in parallel.