Was There Water on Ancient Mars?
Despite Mars’s bleak,cold climate today,there is abundant geologic evidence that liquid water once flowed on the Martian surface (and even recent evidence that some water still periodically flows today).The evidence of past flows includes river channels,now dry,that were once carved by powerful foods,valley networks of branching streams and tributaries indicating precipitation falling over wide areas,river deltas and layered sediments suggesting flow into standing bodes of liquid water,and salt and other minerals that dissolved in liquid water and were left behind when water evaporated. When that ancient wet period existed and when it ended is difficult to say.
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