Glaciers
Many of the volcanoes on Mars show strong evidence of past and possible present glacial activity. When glaciers melt and retreat, they leave behind material that was carried in and on the ice. Often the material is dropped in a ridge, called a moraine. An example of moraines is showed in the picture below from the flank of Arsia Mons, a picture taken with the Mars Odyssey THEMIS.
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Ridges on side of Arsia Mons, a large volcano, may be moraines dropped by glacial activity.
Read more about this topic: Phoenicis Lacus Quadrangle