ancient lake on Mars

[Seth]

http://www.sciencedaily.com/releases/2009/06/090617171821.htm

[Henry Blewer]

I thought that one of the Rovers had determined that open water shaped much of the Martian surface. Further evidence is always good however. Thanks for posting this.

[Marcos Silveira]

I wonder how water kept liquid under so low density atmosphere.
Doesn't water boils on Mars surface?!?! What keeps Earth's water liquid isn't nor only the gravity force but it combined with the atmosphere pressure. But in the other hand, shouldn't exist ice in space too tough it exists... Maybe water's physic tension keep the molecules united...
Hah, forget it, i'm getting crazy. 

[Henry Blewer]

There is a theory about that. Mars has lost its volcanism. Without the molten core spinning at its center, it no longer generates the magnetic field Earth has. This allowed the sun to erode the atmosphere. Water has either boiled away into space, or leached down into the surface so it no longer covers the surface. I think that as it dried out, it still formed clouds. These were lost with much of the atmosphere.

[matrix2003]

If you use Google Mars and search for Shalbatana, the evidence of river beds and erosion are quite obvious.
You would be hard pressed to convince any of us that something other than water and a lot of time created
these features!

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edit:   "sorry I forgot English " -  as in corrected blatant spelling error.