Hellas Crater in the ancient highlands contains some of the clearest evidence on Mars for glacial processes. This image, on the eastern margin of the giant impact crater, shows a number of features consistent with glaciation.
There are roughly north-south running ridges and troughs which mark the deposition of sediment called moraine underneath or beside a glacier. There are also sinuous channels which may formed from meltwater underneath a glacier. A small (3.5 x 3.5 kilometer) cutout shows an example of the moraine and meltwater channel.
Image credit: NASA/JPL/University of Arizona
Note: For more information, see PIA18647: Glaciation at the Eastern Hellas Margin.