Layered Deposits in Ritchey Crater (Enhanced Natural Colors; credits for the additional process. and color.: Dr Paolo C. Fienga - Lunexit Team)

This HiRISE image shows eroding layered deposits in Ritchey Crater, a large impact crater in the Southern Highlands.
Three general units can be seen: a relatively dark upper layer, a light middle unit, and the floor material, which may be mostly obscured by dust.
The dark cap layer appears to be relatively hard and resistant, while the light material is weak.
Once the upper layer is removed, the light layer does not last long.

It is unclear how each of these layers formed.
Volcanic ash layers, lake or stream deposits, or sandstone deposited by dunes can all produce horizontal layers. Unraveling the origin would provide important clues to Mars' past.