A Song of Ice and Tectonics

Many craters in the mid-latitudes of Mars are partially filled with deposits that have been interpreted to be ice-rich. We expect the deposits to have formed at an earlier (but relatively recent) time when Mars' orbital parameters were different and allowed ice to condense and deposit in these locations. The ice is covered by dust layers protecting it from sublimating away. The ice deposits are probably no older than a few million years, which is recent in geological terms. However, we can observe that these deposits have been affected by even more recent movement of the crust (the curving trough) that clearly post-dates the ice deposits because it is cutting through them. A wider view allows us to trace this crustal movement or "fault," and we can see it is also affecting the crater wall and the area surrounding it. This observation indicates that Mars' interior is still (or at least until recently was) warm enough to sustain such activity. https://photojournal.jpl.nasa.gov/catalog/PIA26323