Polygons, Crater Layers, and Defrosting Dunes (ctx frame - MULTISPECTRUM-2; credits: Lunexit)

The North Polar Region is surrounded by a large sea (erg) of dark sand dunes that become covered by seasonal CO2.
As the Northern Hemisphere begins to warm in the Spring, the frozen CO2 sublimates.

The wind blows from an East-Northeasterly direction and leaves dark streaks behind (exposed basalt) from the evaporating Carbon Dioxide. This image displays defrosting sand dunes in an unnamed crater.