Cliffs of Ice

The mid-latitudes of Mars are mostly covered with smooth material that scientists have suspected to be ice for some time. The ground is uniform and dusty and does not reveal many clues about what lies beneath the surface. However, sometimes a feature like a cliff cuts through the terrain and gives us a glimpse of this buried icy material. The cliff in this image is one example out of a few dozen that are known. The bright material on the cliff face is icy and is preserved only because the cliff points away from the equator, so it is shaded most of the time. Faint bands on the cliff might indicate layers in the ice that record different climate conditions. We do not know how much time this ice took to accumulate here, but studies elsewhere on Mars indicate that material like this is sometimes at least tens of millions of years old. https://photojournal.jpl.nasa.gov/catalog/PIA25505