This is interesting; the discovery by Mars Reconnaissance Orbiter of clay deposits in Mawrth Vallis which contain a layer of reduced (ferrous) iron, which, according to Janice Bishop, team leader of a new study just published in the journal Science, usually involves microbes.

Not proof of anything yet, and there may be alternative explanations, but it's another piece of the puzzle...

http://www.space.com/scienceastronom...s-clay-02.html

At any rate, the discovery and further study of these extensive and varied clay deposits provides more evidence for previous long-standing and widespread bodies of water on ancient Mars.

http://www.seti.org/news/press-relea...tian-clays.php

Paul

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