Since the ice deposits discovered in today’s study were found intact along the scarps’ steep, eroded slopes, the researchers believe the ice is “cohesive and strong.” Furthermore, the team found that the ice appears banded, showing layered variations in its blue color. This suggests that the massive ice deposits are composed of many distinct layers that have been squished together over time, preserving a record of Mars’ climate history. However, because there are few craters near these sites, the authors suggest the ice was formed relatively recently — in the past million years or so.Although the massive ice deposits formed quickly (geologically speaking), the researchers say they also recede a tiny bit each summer. In one scarp, the team found that over the course of only three martian years, multiple meter-wide boulders dislodged themselves from the ice deposits, tumbling down into the valley below. Based on this, the researchers estimated the ice is retreating (horizontally) at a rate of a few millimeters each year. This is probably due to the exposed, solid ice sublimating into gas as it contacts the thin martian air.The discovery of these large reservoirs of pure water ice adds yet another piece of evidence supporting the increasingly held theory that water ice not only exists on Mars, but also is surprisingly common. Although the ice could obviously be used as a source of water for future manned missions to Mars, scientists have a long way to go before then. However, with the Mars 2020 rover just a few years away, the discovery of eight more tantalizing sites ripe for investigation is still an exciting find.