Did ancient snowfall carve Martian valleys?

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Ancient snowfall likely carved Martian valleys

PROVIDENCE, R.I. [brown University] — Valley networks branching across the Martian surface leave little doubt that water once flowed on the Red Planet. But where that ancient water came from — whether it bubbled up from underground or fell as rain or snow — is still debated by scientists. A new study by researchers at Brown University puts a new check mark in the precipitation column.

The study finds that water-carved valleys at four different locations on Mars appear to have been caused by runoff from orographic precipitation — snow or rain that falls when moist prevailing winds are pushed upward by mountain ridges. The new findings are the most detailed evidence yet of an orographic effect on ancient Mars and could shed new light on the planet’s early climate and atmosphere.

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