THEMIS Image of the Day, December 31, 2018. This VIS image is located along the edge of the south polar cap.
In the upper right corner the non-polar surface is visible. The tightly packed layers to the left are the edge of the polar cap, a very steep cliff-like feature.
At the bottom half of the image is a surface where some, but not all, of the polar layers have been eroded away.
This surface illustrates how the polar layering forms, filling in the low regions first until all the topography is covered.