Underground Glaciers on Mars?

The Mars Reconnaissance Orbiter has detected what NASA scientists believe are huge glaciers of water ice lying beneath a layer of rocky debris.
The finding is significant because it helps scientists better understand a feature of the Martian surface that has puzzled them for decades. In the 1970s, the Viking orbiters sent back images that showed what have been dubbed “aprons,” or large, gently sloping deposits of debris situated at the base of tall geographic formations like cliffs. Several theories for what created these aprons have been posed over the years. This research indicates that what’s just beneath that debris is of much greater interest.