Exposure of Basal Section of South Polar Layered Deposits (MULTISPECTRUM; credits: Lunexit)

This observation shows internal layering exposed in a so-called "Basal Section" of the Polar Layered Deposits.
The South Polar Layered Deposits are composed primarily of water ice with a small amount of dust.

Variations in dust content most likely controls the erosion of the layers. The layers were laid down over a large area near the South Pole, probably over the past few million years. They are believed to record recent global climate changes on Mars in much the same way that polar ice in Greenland and Antarctica provide information about varying climatic conditions on Earth.

Several layers appear to be truncated and most likely represent unconformities. Unconformities form when an episode of erosion that removes all or part of a layer, is followed by more deposition.