Deposits of water are found on Mars where "it isn't necessary" - in the equatorial part

 Within the last several years on the surface of Mars quite large number of "traces" of the fact that in ancient times on the red planet there were both rivers, and lakes, and even oceans which all combined on the volume of the water which is contained in them could compete with our Arctic Ocean has been found. However there are scientists who are inclined to consider that even in an extreme antiquity Mars was too cold for long existence of oceans on his surface. 

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Interesting article. I want to learn the true origin of the rivers and lakes on Mars. How long have they disappeared? Where that water what was on Mars in liquid state? And whether there was Mars always such cold?