Evidence of liquid water on Mars has been discovered in a crater that is only 200,000 years old. The water is supposed to have been created by melting snow after the crater was formed. As such, the suggestion is that liquid water existed on Mars only 200,000 years ago. Per the article:
New research has shown that there was liquid water on Mars as recently as 200,000 years ago. The southern hemisphere of Mars is home to a crater that contains very well-preserved gullies and debris flow deposits. The geomorphological attributes of these landforms provide evidence that they were formed by the action of liquid water in geologically recent time...."What surprised us was that the crater in which these debris flows have formed is so young," says Andreas Johnsson of the Department of Earth Sciences, University of Gothenburg....Crater statistics allowed Andreas Johnsson and his co-authors to determine that the age of the crater (is) approximately 200,000 years....." It is more likely that the water has come from melting snow packs, when the conditions were favorable for snow formation...."
The results have been published in the international scientific journal, Icarus.
Cool article - thanks